[ADD] playground: add monkey patching example

closes #312
2025-10-06 19:59:41 +07:00 · 2019-10-05 09:00:23 +02:00
125 changed files with 21530 additions and 24217 deletions
@@ -1,10 +1,10 @@
 <h1 align="center">🦉 <a href="https://odoo.github.io/owl/">Odoo Web Library</a> 🦉</h1>

-_Class based components with hooks, reactive state and concurrent mode_
+_A no nonsense web framework for structured, dynamic and maintainable applications_

 ## Project Overview

-The Odoo Web Library (OWL) is a smallish (~<20kb gzipped) UI framework intended to
+The Odoo Web Library (OWL) is a smallish (~17kb gzipped) UI framework intended to
 be the basis for the [Odoo](https://www.odoo.com/) Web Client. Owl is a modern
 framework, written in Typescript, taking the best ideas from React and Vue in a
 simple and consistent way. Owl's main features are:
@@ -20,24 +20,25 @@ virtual dom, integrates beautifully with hooks, and the rendering is asynchronou
 **Try it online!** An online playground is available at [https://odoo.github.io/owl/playground](https://odoo.github.io/owl/playground) to let you experiment with the Owl framework. There
 are some code examples to showcase some interesting features.

-Owl is currently mostly stable.  Possible future changes are explained in the
-[roadmap](roadmap.md).
-
 ## Example

 Here is a short example to illustrate interactive components:

 ```javascript
-const { Component, useState } = owl;
-const { xml } = owl.tags;
+import { Component, QWeb, useState } from "owl";
+import { xml } from "owl/tags";

 class Counter extends Component {
  static template = xml`
-    <button t-on-click="state.value++">
+    <button t-on-click="increment">
      Click Me! [<t t-esc="state.value"/>]
    </button>`;

  state = useState({ value: 0 });
+
+  increment() {
+    this.state.value++;
+  }
 }

 class App extends Component {
@@ -50,12 +51,12 @@ class App extends Component {
  static components = { Counter };
 }

-const app = new App();
+const app = new App({ qweb: new QWeb() });
 app.mount(document.body);
 ```

-Note that the counter component is made reactive with the [`useState` hook](doc/reference/hooks.md#usestate).
-Also, all examples here uses the [`xml` helper](doc/reference/tags.md#xml-tag) to define inline templates.
+Note that the counter component is made reactive with the [`useState`](doc/hooks.md#usestate)
+hook. Also, all examples here uses the `xml` helper to define inline templates.
 But this is not mandatory, many applications will load templates separately.

 More interesting examples can be found on the
@@ -86,16 +87,11 @@ find some more information [here](doc/comparison.md).

 ## Documentation

-A complete documentation for Owl can be found here:
+The complete documentation can be found [here](doc/readme.md). The most important sections are:

- [Main documentation page](doc/readme.md).
-
-The most important sections are:
-
- [Tutorial: TodoList application](doc/learning/tutorial_todoapp.md)
- [QWeb templating language](doc/reference/qweb_templating_language.md)
- [Component](doc/reference/component.md)
- [Hooks](doc/reference/hooks.md)
+- [Quick Start](doc/quick_start.md)
+- [Component](doc/component.md)
+- [Hooks](doc/hooks.md)

 Found an issue in the documentation? A broken link? Some outdated information?
 Submit a PR!
@@ -104,8 +100,8 @@ Submit a PR!

 If you want to use a simple `<script>` tag, the last release can be downloaded here:

- [owl-1.0.0-beta2.js](https://github.com/odoo/owl/releases/download/v1.0.0-beta2/owl.js)
- [owl-1.0.0-beta2.min.js](https://github.com/odoo/owl/releases/download/v1.0.0-beta2/owl.min.js)
+- [owl-0.22.0.js](https://github.com/odoo/owl/releases/download/v0.22.0/owl.js)
+- [owl-0.22.0.min.js](https://github.com/odoo/owl/releases/download/v0.22.0/owl.min.js)

 Some npm scripts are available:

@@ -128,6 +124,23 @@ Owl components in an application are used to define a (dynamic) tree of componen
     C   D
 ```

+**Environment:** the root component is special: it is created with an environment,
+which should contain a `QWeb` instance. The environment is then automatically
+propagated to each sub components (and accessible in the `this.env` property).
+
+```js
+const env = { qweb: new QWeb() };
+const app = new App(env);
+app.mount(document.body);
+```
+
+The environment is mostly static. Each application is free to add anything to
+the environment, which is very useful, since this can be accessed by each sub
+component. Some good use case for that is some configuration keys, session
+information or generic services (such as doing rpcs, or accessing local storage).
+Doing it this way means that components are easily testable: we can simply
+create a test environment with mock services.
+
 **State:** each component can manage its own local state. It is a simple ES6
 class, there are no special rules:

@@ -170,12 +183,6 @@ class Counter extends Component {
 }
 ```

-Note that the `t-on-click` handler can even be replaced by an inline statement:
-
-```xml
-    <button t-on-click="state.value++">
-```
-
 **Props:** sub components often needs some information from their parents. This
 is done by adding the required information to the template. This will then be
 accessible by the sub component in the `props` object. Note that there is an
@@ -239,7 +246,7 @@ class Parent extends Component {
 In this example, the `OrderLine` component trigger a `add-to-order` event. This
 will generate a DOM event which will bubble along the DOM tree. It will then be
 intercepted by the parent component, which will then get the line (from the
-`detail` key) and then increment its quantity. See the section on [event handling](doc/reference/component.md#event-handling)
+`detail` key) and then increment its quantity. See the section on [event handling](doc/component.md#event-handling)
 for more details on how events work.

 Note that this example would have also worked if the `OrderLine` component
@@ -30,7 +30,7 @@ btn {
 }
 ```

-will produce a nice flash effect whenever the user clicks (or activates with the
+will produce a nice flash effect whenever the user click (or activate with the
 keyboard) the button.

 ## CSS Transitions
@@ -47,7 +47,7 @@ the lifetime of a node. Since this is not easy to do by hand, Owl `t-transition`
 directive is there to help.

 Whenever a node has a `t-transition` directive, with a `name` value, the following
-sequence of events will happen:
+will happen:

 At node insertion:

@@ -91,5 +91,6 @@ The `t-transition` directive can be applied on a node element or on a component.

 Notes:

-Owl does not support more than one transition on a single node, so the
-`t-transition` expression must be a single value (i.e. no space allowed).
+- more information on animations are available [here](animations.md).
+- Owl does not support more than one transition on a single node, so the
+  `t-transition` expression must be a single value (i.e. no space allowed)
@@ -1,32 +0,0 @@
-# 🦉 Rendering Pipeline 🦉
-
-We explain here how Owl is designed, from the perspective of its rendering
-pipeline.
-
-Warning: these notes are technical by nature, and intended for people working
-on Owl (or interested in understanding its design).
-
-## Overview
-
-A rendering occurs in two phases:
-
- virtual rendering: this generates the virtual dom in memory, asynchronously
- patch: applies a virtual tree to the screen (synchronously)
-
-There are several classes involved in a rendering:
-
- components
- a scheduler
- fibers: small objects containing some metadata, associated with a rendering of
-  a specific component
-
-Components are organized in a dynamic component tree, visible in the user
-interface. Whenever a rendering is initiated in a component `C`:
-
- a fiber is created on `C` with the rendering props information
- the virtual rendering phase starts on C (will asynchronously render all the
-  child components)
- the fiber is added to the scheduler, which will poll continuously, every
-  animation frame, if the fiber is done
- once it is done, the scheduler will call the task callback, which will apply
-  the patch (if it was not cancelled in the meantime).
@@ -3,7 +3,7 @@
 OWL, React and Vue have the same main feature: they allow developers to build
 declarative user interfaces. To do that, all these frameworks uses a virtual dom. However, there are still obviously many differences.

-In this page, we try to highlight some of these differences. Obviously, a lot of
+In this page, we try to highlight some of these differences. Obviously, some
 effort was done to be fair. However, if you disagree with some of the points
 discussed, feel free to open an issue/submit a PR to correct this text.

@@ -16,7 +16,6 @@ discussed, feel free to open an issue/submit a PR to correct this text.
 - [Asynchronous rendering](#asynchronous-rendering)
 - [Reactiveness](#reactiveness)
 - [State Management](#state-management)
- [Hooks](#hooks)

 ## Size

@@ -25,16 +24,11 @@ than React and Vue. Also, jQuery is not the same kind of framework, but it is in

 | Framework                | Size (minified, gzipped) |
 | ------------------------ | ------------------------ |
-| OWL                      | 18kb                     |
+| OWL                      | 16kb                     |
 | Vue + VueX               | 30kb                     |
-| Vue + VueX + Vue Router  | 39kb                     |
 | React + ReactDOM + Redux | 40kb                     |
 | jQuery                   | 30kb                     |

-Note that those comparisons are not entirely fair, because we do not compare
-the same exact set of features. For example, VueX and Vue Router support more
-advanced use cases.
-
 ## Class Based

 Both React and Vue moved away from defining components with classes. They prefer
@@ -46,17 +40,6 @@ contrast, Owl has only one mechanism: class-based components. We believe that Ow
 components are fast enough for all our usecases, and making it as simple as
 possible for developers is more valuable (for us).

-Also, functions or class based components are more than just syntax. Functions
-comes with a mindset of composition and class are about inheritance. Clearly,
-both of these are important mechanisms for reusing code. Also, one does not
-exclude the other.
-
-It certainly looks like the world of UI frameworks is moving toward composition,
-for many very good reasons. Owl is still good at composition (for example,
-Owl supports slots, which is the primary mechanism to make generic reusable
-components). But it can also use inheritance (and this is very important since
-templates can also be inherited with `xpaths` transformations).
-
 ## Tooling/Build step

 OWL is designed to be easy to use in a standalone way. For various reasons,
@@ -67,23 +50,13 @@ be used by simply adding a script tag to a page.
 <script src="owl.min.js" />
 ```

-In comparison, React encourages using JSX, which necessitate a build step, and
-most Vue applications uses single file components, which also necessitate a build step.
+In comparison, React encourages using JSX,
+which necessitate a build step, and most Vue applications uses single file
+components, which also necessitate a build step.

 On the flipside, external tooling may make it harder to use in some case, but it
 also brings a lot of benefits. And React/Vue have both a large ecosystem.

-Note that since Owl is not dependant on any external tool nor libraries, it is
-very easy to integrate into any build toolchain. Also, since we cannot rely on
-additional tools, we made a lot of effort to make the most of the web platform.
-
-For example, Owl uses the standard `xml` parser that comes with every browser.
-Because of that, Owl did not have to write its own template parser. Another
-example is the [`xml`](reference/tags.md#xml-tag) tag helper function, which makes use of
-native template literals to allow in a natural way to write `xml` templates
-directly in the javascript code. This can be easily integrated with editor
-plugins to have autocompletion inside the template.
-
 ## Templating

 OWL uses its own QWeb engine, which compiles templates on the
@@ -106,8 +79,7 @@ into javascript functions. Note that Vue has a separate build which includes the
 template compiler.

 In contrast, most React applications do not use a templating language, but write
-some JSX code, which is precompiled into plain JavaScript by a build step. This
-example is done with the (kind of outdated) React class system:
+some JSX code, which is precompiled into plain JavaScript by a build step.

 ```jsx
 class Clock extends React.Component {
@@ -126,20 +98,6 @@ This has the advantage of having the full power of Javascript, but is less
 structured than a template language. Note that the tooling is quite impressive:
 there is a syntax highlighter for jsx here on github!

-By comparison, here is the equivalent Owl component, written with the
-[`xml`](reference/tags.md#xml-tag) tag helper:
-
-```js
-class Clock extends Component {
-  static template = xml`
-      <div>
-        <h1>Hello, world!</h1>
-        <h2>It is {props.date.toLocaleTimeString()}.</h2>
-      </div>
-    `;
-}
-```
-
 ## Asynchronous Rendering

 This is actually a big difference between OWL and React/Vue: components in OWL
@@ -169,14 +127,12 @@ This may be dangerous (to stop the rendering waiting for the network), but it is
 extremely powerful as well, as demonstrated by the Odoo Web Client.

 Lazy loading static libraries can obviously be done with React/Vue, but it is
-more convoluted. For example, in Vue, you need to use a dynamic import keyword
-that needs to be transpiled at build time in order for the component to be loaded
-asynchronously (see [the documentation](https://vuejs.org/v2/guide/components-dynamic-async.html#Async-Components)).
+more convoluted.

 ## Reactiveness

 React has a simple model: whenever the state changes, it is
-replaced with a new state (via the `setState` method). Then, the DOM is patched.
+replaced with a new state (via the setState method). Then, the DOM is patched.
 This is simple, efficient, and a little bit awkward to write.

 Vue is a little bit different: it replace magically the properties in the state
@@ -251,95 +207,30 @@ keeps track of who get data, and retrigger a render when it was changed.
 Owl store is a little bit like a mix of redux and vuex: it has actions (but not
 mutations), and like VueX, it keeps track of the state changes. However, it does
 not notify a component when the state changes. Instead, components need to connect
-to the store like in redux, with the `useStore` hook (see the [store documentation](reference/store.md#connecting-a-component)).
+to the store like in redux, by inheriting the `ConnectedComponent` class.

 ```javascript
 const actions = {
  increment({ state }, val) {
-    state.counter.value += val;
+    state.counter += val;
  }
 };

 const state = {
-  counter: { value: 0 }
+  counter: 0
 };
 const store = new owl.Store({ state, actions });

-class Counter extends Component {
-  static template = xml`
-      <button t-name="Counter" t-on-click="dispatch('increment')">
-        Click Me! [<t t-esc="counter.value"/>]
-      </button>`;
-  counter = useStore(state => state.counter);
-  dispatch = useDispatch();
-}
-
-Counter.env.store = store;
-const counter = new Counter();
-```
-
-## Hooks
-
-[Hooks](https://reactjs.org/docs/hooks-intro.html#motivation) recently took over
-the React world. They solve a lot of seemingly unconnected problems: attach
-reusable behavior to a component, in a composable way, extract stateful logic
-from a component or reuse stateful logic between component, without changing your
-component hierarchy.
-
-Here is an example of the React `useState` hook:
-
-```js
-import React, { useState } from "react";
-
-function Example() {
-  // Declare a new state variable, which we'll call "count"
-  const [count, setCount] = useState(0);
-
-  return (
-    <div>
-      <p>You clicked {count} times</p>
-      <button onClick={() => setCount(count + 1)}>Click me</button>
-    </div>
-  );
-}
-```
-
-Because of the way React designed the hooks API, they only work for functional
-components. But in that case, they really are powerful. Every major React library
-is in the process of redesigning their API with hooks (for example,
-[Redux](https://react-redux.js.org/next/api/hooks)).
-
-Vue 2 does not have hooks, but the Vue project is working on its next version,
-which will feature its new [composition API](https://vue-composition-api-rfc.netlify.com/).
-This work is based on the new ideas introduced by React hooks.
-
-From the way React and Vue introduce their hooks, it may look like hooks are not
-compatible with class components. However, this is not the case, as shown by
-Owl [hooks](reference/hooks.md). They are inspired by both React and Vue. For example,
-the `useState` hook is named after React, but its API is closer to the `reactive`
-Vue hook.
-
-Here is what the `Counter` example above look like in Owl:
-
-```js
-import { Component, Owl } from "owl";
-import { xml } from "owl/tags";
-
-class Example extends Component {
-  static template = xml`
-      <div>
-        <p>You clicked {count.value} times</p>
-        <button t-on-click="increment">Click me</button>
-      </div>`;
-
-  count = useState({ value: 0 });
-
+class Counter extends owl.ConnectedComponent {
+  static mapStoreToProps(state) {
+    return {
+      value: state.counter
+    };
+  }
  increment() {
-    this.state.value++;
+    this.env.store.dispatch("increment");
  }
 }
-```

-Since the Owl framework had hooks from early in its life, its main APIs
-are designed to be interacted with hooks from the start. For example, the
-`Context` and `Store` abstractions.
+const counter = new Counter({ store, qweb });
+```
@@ -11,12 +11,16 @@
  - [Methods](#methods)
  - [Lifecycle](#lifecycle)
  - [Root Component](#root-component)
+  - [Environment](#environment)
  - [Composition](#composition)
  - [Event Handling](#event-handling)
  - [Form Input Bindings](#form-input-bindings)
+  - [`t-key` Directive](#t-key-directive)
+  - [Semantics](#semantics)
+  - [Props Validation](#props-validation)
  - [References](#references)
  - [Slots](#slots)
-  - [Dynamic sub components](#dynamic-sub-components)
+  - [Asynchronous Rendering](#asynchronous-rendering)
  - [Error Handling](#error-handling)
  - [Functional Components](#functional-components)
  - [SVG components](#svg-components)
@@ -25,7 +29,7 @@

 OWL components are the building blocks for user interface. They are designed to be:

-1. **declarative:** the user interface should be described in terms of the state
+1. **declarative:** the user interface should be described in term of the state
   of the application, not as a sequence of imperative steps.

 2. **composable:** each component can seamlessly be created in a parent component by
@@ -39,7 +43,7 @@ OWL components are the building blocks for user interface. They are designed to
   and follow the QWeb specification. This is a requirement for Odoo.

 OWL components are defined as a subclass of Component. The rendering is
-exclusively done by a [QWeb](qweb_templating_language.md) template (which needs to be preloaded in QWeb).
+exclusively done by a [QWeb](qweb.md) template (which needs to be preloaded in QWeb).
 Rendering a component generates a virtual dom representation
 of the component, which is then patched to the DOM, in order to apply the changes in an efficient way.

@@ -68,7 +72,7 @@ class ClickCounter extends owl.Component {
 Note that this code is written in ESNext style, so it will only run on the
 latest browsers without a transpilation step.

-This example shows how a component should be defined: it simply subclasses the
+This example show how a component should be defined: it simply subclasses the
 Component class. If no static `template` key is defined, then
 Owl will use the component's name as template name. Here,
 a state object is defined, by using the `useState` hook. It is not mandatory to use the state object, but it is certainly encouraged. The result of the `useState` call is
@@ -76,112 +80,45 @@ a state object is defined, by using the `useState` hook. It is not mandatory to

 ## Reference

-An Owl component is a small class which represents a component or some UI element.
-It exists in the context of an [environment](environment.md) (`env`), which is propagated from a
-parent to its children. The environment needs to have a [QWeb](qweb_templating_language.md) instance, which
+An Owl component is a small class which represent a component or some UI element.
+It exists in the context of an environment (`env`), which is propagated from a
+parent to its children. The environment needs to have a QWeb instance, which
 will be used to render the component template.

 Be aware that the name of the component may be significant: if a component does
 not define a `template` key, then Owl will lookup in QWeb to
-find a template with the component name (or one of its ancestors).
+find a template with the component name (or one of its ancestor).

 ### Reactive system

-OWL components are normal javascript classes. So, changing a component internal
-state does nothing more:
+OWL components can be made reactive by observing some part of their state. See the [hooks](hooks.md) section for more details.

-```js
-class Counter extends Component {
-  static template = xml`<div t-on-click="increment"><t t-esc="state.value"/></div>`;
-  state = { value: 0 };
-
-  increment() {
-    this.state.value++;
-  }
-}
-```
-
-Clicking on the `Counter` component defined above will call the `increment`
-method, but it will not rerender the component. To fix that, one could add an
-explicit call to `render` in `increment`:
-
-```js
-    increment() {
-        this.state.value++;
-        this.render();
-    }
-```
-
-However, it may be simple in this case, but it quickly become cumbersome, as a
-component get more complex, and its internal state is modified by more than one
-method.
-
-A better way is to use the reactive system: by using the `useState` hook (see the
-[hooks](hooks.md) section for more details), one can make Owl react to state
-changes. The `useState` hook generates a proxy version of an object
+The main idea is that the `useState` hook generate a proxy version of an object
 (this is done by an [observer](observer.md)), which allows the component to
-react to any change. So, the `Counter` example above can be improved like this:
+react to any change.

-```js
+```javascript
 const { useState } = owl.hooks;

-class Counter extends Component {
-  static template = xml`<div t-on-click="increment"><t t-esc="state.value"/></div>`;
-  state = useState({ value: 0 });
-
-  increment() {
-    this.state.value++;
-  }
+class SomeComponent extends owl.Component {
+  state = useState({ a: 0, b: 1 });
 }
 ```

-Obviously, we can call the `useState` hook more than once:
-
-```js
-const { useState } = owl.hooks;
-
-class Counter extends Component {
-  static template = xml`
-      <div>
-        <span t-on-click="increment(counter1)"><t t-esc="counter1.value"/></span>
-        <span t-on-click="increment(counter2)"><t t-esc="counter2.value"/></span>
-      </div>`;
-  counter1 = useState({ value: 0 });
-  counter2 = useState({ value: 0 });
-
-  increment(counter) {
-    counter.value++;
-  }
-}
-```
-
-Note that hooks are subject to one important [rule](hooks.md#one-rule): they need
-to be called in the constructor.
+Note that there is an important limitation: hooks need to be called in the
+constructor.

 ### Properties

 - **`el`** (HTMLElement | null): reference to the DOM root node of the element. It is `null` when the
  component is not mounted.

- **`env`** (Object): the component [environment](environment.md), which contains a QWeb instance.
+- **`env`** (Object): the component environment, which contains a QWeb instance.

- **`props`** (Object): this is an object containing all the properties given by
-  the parent to a child component. For example, in the following situation,
-  the parent component gives a `user` and a `color` value to the `ChildComponent`.
-
-  ```xml
-    <div>
-      <ChildComponent user="state.user" color="color">
-    </div>
-  ```
-
-  Note that `props` are owned by the parent, not by the component.
-  As such, it should not ever be modified by the component (otherwise you risk
-  unintended effects, since the parent may not be aware of the change)!!
-
-  The `props` can be modified dynamically by the parent. In that case, the
-  component will go through the following lifecycle methods: `willUpdateProps`,
-  `willPatch` and `patched`.
+- **`props`** (Object): this is an object given (in the constructor) by the parent
+  to configure the component. It can be dynamically changed later by the parent,
+  in some case. Note that `props` are owned by the parent, not by the component.
+  As such, it should not ever be modified by the component!!

 ### Static Properties

@@ -201,7 +138,7 @@ to be called in the constructor.
 * **`props`** (Object, optional): if given, this is an object that describes the
  type and shape of the (actual) props given to the component. If Owl mode is
  `dev`, this will be used to validate the props each time the component is
-  created/updated. See [Props Validation](props_validation.md) for more information.
+  created/updated. See [Props Validation](#props-validation) for more information.

  ```js
  class Counter extends owl.Component {
@@ -225,69 +162,45 @@ to be called in the constructor.
  }
  ```

-There is another static property defined on the `Component` class: `current`.
-This property is set to the currently being defined component (in the constructor).
-This is the way [hooks](hooks.md) are able to get a reference to the target
-component.
-
 ### Methods

 We explain here all the public methods of the `Component` class.

- **`mount(target, options)`** (async): this is the main way a
+- **`mount(target, renderBeforeRemount=false)`** (async): this is the main way a
  component is added to the DOM: the root component is mounted to a target
-  HTMLElement (or document fragment). Obviously, this is asynchronous, since each children need to be
+  HTMLElement. Obviously, this is asynchronous, since each children need to be
  created as well. Most applications will need to call `mount` exactly once, on
  the root component.

-  The `options` argument is an optional object with a `position` key. The
-  `position` key can have three possible values: `first-child`, `last-child`, `self`.
+  The `renderBeforeRemount` argument is useful when a component is unmounted and remounted.
+  In that case, we may want to rerender the component _before_ it is remounted, if
+  we know that its state (or something in the environment, or ...) has changed.
+  In that case, it should simply set to `true`.

-  - `first-child`: with this option, the component will be prepended inside the target,
-  - `last-child` (default value): with this option, the component will be
-    appended in the target element,
-  - `self`: the target will be used as the root element for the component. This
-    means that the target has to be an HTMLElement (and not a document fragment).
-    In this situation, it is possible that the component cannot be unmounted. For
-    example, if its target is `document.body`.
-
-  Note that if a component is mounted, unmounted and remounted, it will be
-  automatically re-rendered to ensure that changes in its state (or something
-  in the environment, or in the store, or ...) will be taken into account.
-
-  If a component is mounted inside an element or a fragment which is not in the
-  DOM, then it will be rendered fully, but not active: the `mounted` hooks will
-  not be called. This is sometimes useful if we want to load an application in
-  memory. In that case, we need to mount the root component again in an element
-  which is in the DOM:
-
-  ```js
-  const app = new App();
-  await app.mount(document.createDocumentFragment());
-  // app is rendered in memory, but not active
-  await app.mount(document.body);
-  // app is now visible
-  ```
-
-* **`unmount()`**: in case a component needs to be detached/removed from the DOM, this
+- **`unmount()`**: in case a component need to be detached/removed from the DOM, this
  method can be used. Most applications should not call `unmount`, this is more
  useful to the underlying component system.

-* **`render()`** (async): calling this method directly will cause a rerender. Note
+- **`render()`** (async): calling this method directly will cause a rerender. Note
  that this should be very rare to have to do it manually, the Owl framework is
  most of the time responsible for doing that at an appropriate moment.

  Note that the render method is asynchronous, so one cannot observe the updated
  DOM in the same stack frame.

-* **`shouldUpdate(nextProps)`**: this method is called each time a component's props
+- **`shouldUpdate(nextProps)`**: this method is called each time a component's props
  are updated. It returns a boolean, which indicates if the component should
  ignore a props update. If it returns false, then `willUpdateProps` will not
  be called, and no rendering will occur. Its default implementation is to
  always return true. This is an optimization, similar to React's `shouldComponentUpdate`. Most of the time, this should not be used, but it
  can be useful if we are handling large number of components.

-* **`destroy()`**. As its name suggests, this method will remove the component,
+- **`updateEnv(nextEnv)`**: update the environment of a component and all its
+  children. This forces a complete rerender. For example, this could be useful
+  if we have a `isMobile` key in the environment, to decide if we want a mobile
+  interface or a destkop one.
+
+- **`destroy()`**. As its name suggests, this method will remove the component,
  and perform all necessary cleanup, such as unmounting the component, its children,
  removing the parent/children relationship. This method should almost never be
  called directly (except maybe on the root component), but should be done by the
@@ -390,8 +303,8 @@ will slightly slow down the component.
 #### `willUpdateProps(nextProps)`

 The willUpdateProps is an asynchronous hook, called just before new props
-are set. This is useful if the component needs to perform an asynchronous task,
-depending on the props (for example, assuming that the props are
+are set. This is useful if the component needs some asynchronous task
+performed, depending on the props (for example, assuming that the props are
 some record Id, fetching the record data).

 ```javascript
@@ -406,13 +319,14 @@ and performs a similar job).
 #### `willPatch()`

 The willPatch hook is called just before the DOM patching process starts.
-It is not called on the initial render. This is useful to read
+It is not called on the initial render. This is useful to read some
 information from the DOM. For example, the current position of the
 scrollbar.

 Note that modifying the state is not allowed here. This method is called just
 before an actual DOM patch, and is only intended to be used to save some local
-DOM state. Also, it will not be called if the component is not in the DOM.
+DOM state. Also, it will not be called if the component is not in the DOM (this can
+happen with components with `t-keepalive`).

 #### `patched(snapshot)`

@@ -422,17 +336,17 @@ likely via a change in its state/props or environment).
 This method is not called on the initial render. It is useful to interact
 with the DOM (for example, through an external library) whenever the
 component was patched. Note that this hook will not be called if the compoent is
-not in the DOM.
+not in the DOM (this can happen with components with `t-keepalive`).

-Updating the component state in this hook is possible, but not encouraged.
-One needs to be careful, because updates here will create an additional rendering, which in
-turn will cause other calls to the `patched` method. So, we need to be particularly
+Updating the compoent state in this hook is possible, but not encouraged.
+One need to be careful, because updates here will cause rerender, which in
+turn will cause other calls to patched. So, we need to be particularly
 careful at avoiding endless cycles.

 #### `willUnmount()`

 willUnmount is a hook that is called each time just before a component is unmounted from
-the DOM. This is a good place to remove listeners, for example.
+the DOM. This is a good place to remove some listeners, for example.

 ```javascript
  mounted() {
@@ -449,7 +363,7 @@ This is the opposite method of `mounted`.

 The `catchError` method is useful when we need to intercept and properly react
 to (rendering) errors that occur in some sub components. See the section on
-[error handling](#error-handling).
+[error handling](#error-handling)

 ### Root Component

@@ -460,17 +374,49 @@ of an Owl application has to be created manually:
 ```js
 class App extends owl.Component { ... }

-const app = new App();
+const qweb = new owl.QWeb(TEMPLATES);
+const env = { qweb: qweb };
+const app = new App(env);
 app.mount(document.body);
 ```

-The root component does not have a parent nor `props` (see note below). It will be setup with an
-[environment](environment.md) (either the `env` defined on its class, or a
-default empty environment).
+The root component needs an environment.

-Note: a root component can however be given a `props` object in its constructor,
-like this: `new App(null, {some: 'object'});`. It will not be a true `props`
-object, managed by Owl (so, for example, it will never be updated).
+### Environment
+
+In Owl, an environment is an object with a `qweb` key, which has to be a
+[QWeb](qweb.md) instance. This qweb instance will be used to render everything.
+
+The environment is meant to contain (mostly) static global information and
+methods for the whole application. For example, settings keys (`mode` to determine
+if we are in desktop or mobile mode, or `theme`: dark or light), `rpc` methods,
+session information, ...
+
+The environment will be given to each child, unchanged, in the `env` property.
+This can be very useful to share common information/methods. For example, all
+rpcs can be made through a `rpc` method in the environment. This makes it very
+easy to test a component.
+
+Updating the environment is not as simple as changing a component's state: its
+content is not observed, so updates will not be reflected immediately in the
+user interface. There is however a mechanism to force root widgets to rerender
+themselves whenever the environment is modified: one only needs to call the
+`forceUpdate` method on the QWeb instance. For example, a responsive environment
+could be done like this:
+
+```js
+function setupResponsivePlugin(env) {
+  const isMobile = () => window.innerWidth <= 768;
+  env.isMobile = isMobile();
+  const updateEnv = owl.utils.debounce(() => {
+    if (env.isMobile !== isMobile()) {
+      env.isMobile = !env.isMobile;
+      env.qweb.forceUpdate();
+    }
+  }, 15);
+  window.addEventListener("resize", updateEnv);
+}
+```

 ### Composition

@@ -524,10 +470,68 @@ the static `components` key, then fallbacks on the global registry.
 _Props_: In this example, the child component will receive the object `{count: 4}` in its
 constructor. This will be assigned to the `props` variable, which can be accessed
 on the component (and also, in the template). Whenever the state is updated, then
-the sub component will also be updated automatically. See the [props section](props.md)
-for more information.
+the sub component will also be updated automatically.

-**CSS and style:** Owl allows the parent to declare
+Note that there are some restrictions on prop names: `class`, `style` and any
+string which starts with `t-` are not allowed.
+
+It is not common, but sometimes we need a dynamic component name and/or dynamic props. In this case,
+the `t-component` directive can also be used to accept dynamic values with string interpolation (like the [`t-attf-`](qweb.md#dynamic-attributes) directive):
+
+```xml
+<div t-name="ParentComponent">
+    <t t-component="ChildComponent{{id}}" />
+</div>
+```
+
+```js
+class ParentComponent {
+  static components = { ChildComponent1, ChildComponent2 };
+  state = { id: 1 };
+}
+```
+
+And the `t-props` directive can be used to specify totally dynamic props:
+
+```xml
+<div t-name="ParentComponent">
+    <Child t-props="some.obj"/>
+</div>
+```
+
+```js
+class ParentComponent {
+  static components = { Child };
+  some = { obj: { a: 1, b: 2 } };
+}
+```
+
+There is an even more dynamic way to use `t-component`: its value can be an
+expression evaluating to an actual component class. In that case, this is the
+class that will be used to create the component:
+
+```js
+class A extends Component<any, any, any> {
+  static template = xml`<span>child a</span>`;
+}
+class B extends Component<any, any, any> {
+  static template = xml`<span>child b</span>`;
+}
+class App extends Component<any, any, any> {
+  static template = xml`<t t-component="myComponent" t-key="state.child"/>`;
+
+  state = { child: "a" };
+
+  get myComponent() {
+    return this.state.child === "a" ? A : B;
+  }
+}
+```
+
+In this example, the component `App` selects dynamically the concrete sub
+component class.
+
+**CSS and style:** there is some specific support to allow the parent to declare
 additional css classes or style for the sub component: css declared in `class`, `style`, `t-att-class` or `t-att-style` will be added to the
 root component element.

@@ -540,7 +544,7 @@ root component element.
 Warning: there is a small caveat with dynamic class attributes: since Owl needs
 to be able to add/remove proper classes whenever necessary, it needs to be aware
 of the possible classes. Otherwise, it will not be able to make the difference
-between a valid css class added by the component, or other custom code, and a
+between a valid css class added by the component, or some custom code, and a
 class that need to be removed. This is why we only support the explicit syntax
 with a class object:

@@ -550,7 +554,7 @@ with a class object:

 ### Event Handling

-In a component's template, it is useful to be able to register handlers on DOM
+In a component's template, it is useful to be able to register handlers on some
 elements to some specific events. This is what makes a template _alive_. There
 are four different use cases.

@@ -589,13 +593,11 @@ A _business_ DOM event is triggered by a call to `trigger` on a component.
 }
 ```

-The call to `trigger` generates an `OwlEvent`, a subclass of [_CustomEvent_](https://developer.mozilla.org/docs/Web/Guide/Events/Creating_and_triggering_events)
-with an additional attribute `originalComponent` (the component that triggered
-the event). The generated event is of type `menu-loaded` and dispatches it on
-the component's DOM element (`this.el`). The event bubbles and is cancelable.
-The parent component listening to event `menu-loaded` will receive the payload
-in its `someMethod` handler (in the `detail` property of the event), whenever
-the event is triggered.
+The call to `trigger` generates a [_CustomEvent_](https://developer.mozilla.org/docs/Web/Guide/Events/Creating_and_triggering_events)
+of type `menu-loaded` and dispatches it on the component's DOM element
+(`this.el`). The event bubbles and is cancelable. The parent component listening
+to event `menu-loaded` will receive the payload in its `someMethod` handler
+(in the `detail` property of the event), whenever the event is triggered.

 ```js
 class ParentComponent {
@@ -608,30 +610,6 @@ the event is triggered.

 By convention, we use KebabCase for the name of _business_ events.

-The `t-on` directive allows to prebind its arguments. For example,
-
-```xml
-<button t-on-click="someMethod(expr)">Do something</button>
-```
-
-Here, `expr` is a valid Owl expression, so it could be `true` or some variable
-from the rendering context.
-
-One can also directly specify inline statements. For example,
-
-```xml
-<button t-on-click="state.counter++">Increment counter</button>
-```
-
-Here, `state` must be defined in the rendering context (typically the component)
-as it will be translated to:
-
-```js
-button.addEventListener("click", () => {
-  component.state.counter++;
-});
-```
-
 In order to remove the DOM event details from the event handlers (like calls to
 `event.preventDefault`) and let them focus on data logic, _modifiers_ can be
 specified as additional suffixes of the `t-on` directive.
@@ -651,14 +629,14 @@ the order may matter. For instance `t-on-click.prevent.self` will prevent all
 clicks while `t-on-click.self.prevent` will only prevent clicks on the element
 itself.

-Finally, empty handlers are tolerated as they could be defined only to apply
-modifiers. For example,
+The `t-on` directive also allows to prebind some arguments. For example,

 ```xml
-<button t-on-click.stop="">Do something</button>
+<button t-on-click="someMethod(expr)">Do something</button>
 ```

-This will simply stop the propagation of the event.
+Here, `expr` is a valid Owl expression, so it could be `true` or some variable
+from the rendering context.

 ### Form Input Bindings

@@ -734,12 +712,12 @@ The `t-model` directive works with `<input>`, `<input type="checkbox">`,
 </div>
 ```

-Like event handling, the `t-model` directive accepts the following modifiers:
+Like event handling, the `t-model` directive accepts some modifiers:

 | Modifier  | Description                                                          |
 | --------- | -------------------------------------------------------------------- |
 | `.lazy`   | update the value on the `change` event (default is on `input` event) |
-| `.number` | try to parse the value to a number (using `parseFloat`)              |
+| `.number` | tries to parse the value to a number (using `parseFloat`)            |
 | `.trim`   | trim the resulting value                                             |

 For example:
@@ -753,6 +731,212 @@ update a number whenever the change is done.

 Note: the online playground has an example to show how it works.

+### `t-key` Directive
+
+Even though Owl tries to be as declarative as possible, some DOM state is still
+locked inside the DOM: for example, the scrolling state, the current user selection,
+the focused element or the state of an input. This is why we use a virtual dom
+algorithm to keep the actual DOM node as much as possible. However, this is
+sometimes not enough, and we need to help Owl decide if an element is actually
+the same, or is different. The `t-key` directive is used to give an identity to an element.
+
+There are three main use cases:
+
+- _elements in a list_:
+
+  ```xml
+    <span t-foreach="todos" t-as="todo" t-key="todo.id">
+        <t t-esc="todo.text" />
+    </span>
+  ```
+
+- _`t-if`/`t-else`_
+
+- _animations_: give a different identity to a component. Ex: thread id with
+  animations on add/remove message.
+
+### Semantics
+
+We give here an informal description of the way components are created/updated
+in an application. Here, ordered lists describe actions that are executed
+sequentially, bullet lists describe actions that are executed in parallel.
+
+**Scenario 1: initial rendering** Imagine we want to render the following component tree:
+
+```
+        A
+       / \
+      B   C
+         / \
+        D   E
+```
+
+Here is what happen whenever we mount the root
+component (with some code like `app.mount(document.body)`).
+
+1. `willStart` is called on `A`
+
+2. when it is done, template `A` is rendered.
+
+   - component `B` is created
+     1. `willStart` is called on `B`
+     2. template `B` is rendered
+   - component `C` is created
+     1. `willStart` is called on `C`
+     2. template `C` is rendered
+        - component `D` is created
+          1. `willStart` is called on `D`
+          2. template `D` is rendered
+        - component `E` is created
+          1. `willStart` is called on `E`
+          2. template `E` is rendered
+
+3. component `A` is patched into a detached DOM element. This will create the actual
+   component `A` DOM structure. The patching process will cause recursively the
+   patching of the `B`, `C`, `D` and `E` DOM trees. (so the actual full DOM tree is created
+   in one pass)
+
+4. the component `A` root element is actually appended to `document.body`
+
+5. The method `mounted` is called recursively on all components in the following
+   order: `B`, `D`, `E`, `C`, `A`.
+
+**Scenario 2: rerendering a component**. Now, let's assume that the user clicked on some
+button in `C`, and this results in a state update, which is supposed to:
+
+- update `D`,
+- remove `E`,
+- add new component `F`.
+
+So, the component tree should look like this:
+
+```
+        A
+       / \
+      B   C
+         / \
+        D   F
+```
+
+Here is what Owl will do:
+
+1. because of a state change, the method `render` is called on `C`
+2. template `C` is rendered again
+
+   - component `D` is updated:
+     1. hook `willUpdateProps` is called on `D` (async)
+     2. template `D` is rerendered
+   - component `F` is created:
+     1. hook `willStart` is called on `E` (async)
+     2. template `F` is rendered
+
+3. `willPatch` hooks are called recursively on components `C`, `D` (not on `F`,
+   because it is not mounted yet)
+
+4. component `C` is patched, which will cause recursively:
+
+   2. `willUnmount` hook on `E`, then destruction of `E`,
+   3. (initial) patching of `F`, then hook `mounted` is called on `F`
+
+5. patching of `D`
+
+6. `patched` hooks are called on `D`, `C`
+
+### Props Validation
+
+As an application becomes complex, it may be quite unsafe to define props in an informal way. This leads to two issues:
+
+- hard to tell how a component should be used, by looking at its code.
+- unsafe, it is easy to send wrong props into a component, either by refactoring a component, or one of its parent.
+
+A props type system would solve both issues, by describing the types and shapes
+of the props. Here is how it works in Owl:
+
+- `props` key is a static key (so, different from `this.props` in a component instance)
+- it is optional: it is ok for a component to not define a `props` key.
+- props are validated whenever a component is created/updated
+- props are only validated in `dev` mode (see [tooling page](tooling.md#development-mode))
+- if a key does not match the description, an error is thrown
+- it validates keys defined in (static) `props`. Additional keys given by the
+  parent will cause an error.
+
+For example:
+
+```js
+class ComponentA extends owl.Component {
+    static props = ['id', 'url'];
+
+    ...
+}
+
+class ComponentB extends owl.Component {
+  static props = {
+    count: {type: Number},
+    messages: {
+      type: Array,
+      element: {type: Object, shape: {id: Boolean, text: 'string' }
+    },
+   date: Date,
+   combinedVal: [Number, Boolean]
+  };
+
+  ...
+}
+```
+
+- it is an object or a list of strings
+- a list of strings is a simplified props definition, which only lists the name
+  of the props. Also, if the name ends with `?`, it is considered optional.
+- all props are by default required, unless they are defined with `optional: true`
+  (in that case, validation is only done if there is a value)
+- valid types are: `Number, String, Boolean, Object, Array, Date, Function`, and all
+  constructor functions (so, if you have a `Person` class, it can be used as a type)
+- arrays are homogeneous (all elements have the same type/shape)
+
+For each key, a `prop` definition is either a boolean, a constructor, a list of constructors, or an object:
+
+- a boolean: indicate that the props exists, and is mandatory.
+- a constructor: this should describe the type, for example: `id: Number` describe
+  the props `id` as a number
+- a list of constructors. In that case, this means that we allow more than one
+  type. For example, `id: [Number, String]` means that `id` can be either a string
+  or a number.
+- an object. This makes it possible to have more expressive definition. The following sub keys are then allowed:
+  - `type`: the main type of the prop being validated
+  - `element`: if the type was `Array`, then the `element` key describes the type of each element in the array. It is optional (not set means that we only validate the array, not its elements),
+  - `shape`: if the type was `Object`, then the `shape` key describes the interface of the object. It is optional (not set means that we only validate the object, not its elements)
+
+Examples:
+
+```js
+  // only the existence of those 3 keys is documented
+  static props = ['message', 'id', 'date'];
+```
+
+```js
+  // size is optional
+  static props = ['message', 'size?'];
+```
+
+```js
+  static props = {
+    messageIds: {type: Array, element: Number},  // list of number
+    otherArr: {type: Array},   // just array. no validation is made on sub elements
+    otherArr2: Array,   // same as otherArr
+    someObj: {type: Object},  // just an object, no internal validation
+    someObj2: {
+      type: Object,
+      shape: {
+        id: Number,
+        name: {type: String, optional: true},
+        url: String
+      ]},    // object, with keys id (number), name (string, optional) and url (string)
+    someFlag: Boolean,     // a boolean, mandatory (even if `false`)
+    someVal: [Boolean, Date],   // either a boolean or a date
+    otherValue: true,     // indicates that it is a prop
+  };
+```
+
 ### References

 The `useRef` hook is useful when we need a way to interact with some inside part
@@ -865,63 +1049,46 @@ be considered the `default` slot. For example:
 </div>
 ```

-Slots can define a default content, in case the parent did not define them:
+### Asynchronous Rendering

-```xml
-<div t-name="Parent">
-  <Child/>
-</div>
+Working with asynchronous code always adds a lot of complexity to a system. Whenever
+different parts of a system are active at the same time, one needs to think
+carefully about all possible interactions. Clearly, this is also true for Owl
+components.

-<span t-name="Child">
-  <t t-slot="default">default content</t>
-</span>
-<!-- will be rendered as: <div><span>default content</span></div> -->
-```
+There are two different common problems with Owl asynchronous rendering model:

-### Dynamic sub components
+- any component can delay the rendering (initial and subsequent) of the whole
+  application
+- for a given component, there are two independant situations that will trigger an
+  asynchronous rerendering: a change in the state, or a change in the props.
+  These changes may be done at different times, and Owl has no way of knowing
+  how to reconcile the resulting renderings.

-It is not common, but sometimes we need a dynamic component name. In this case,
-the `t-component` directive can also be used to accept dynamic values with string interpolation (like the [`t-attf-`](qweb_templating_language.md#dynamic-attributes) directive):
+Here are a few tips on how to work with asynchronous components:

-```xml
-<div t-name="ParentComponent">
-    <t t-component="ChildComponent{{id}}" />
-</div>
-```
+1. Minimize the use of asynchronous components!
+2. Maybe move the asynchronous logic in a store, which then triggers (mostly)
+   synchronous renderings
+3. Lazy loading external libraries is a good use case for async rendering. This
+   is mostly fine, because we can assume that it will only takes a fraction of a
+   second, and only once (see `owl.utils.loadJS`)
+4. For all the other cases, the `t-asyncroot` directive (to use alongside
+   `t-component`) is there to help you. When this directive is met, a new rendering
+   sub tree is created, such that the rendering of that component (and its
+   children) is not tied to the rendering of the rest of the interface. It can
+   be used on an asynchronous component, to prevent it from delaying the
+   rendering of the whole interface, or on a synchronous one, such that its
+   rendering isn't delayed by other (asynchronous) components. Note that this
+   directive has no effect on the first rendering, but only on subsequent ones
+   (triggered by state or props changes).

-```js
-class ParentComponent {
-  static components = { ChildComponent1, ChildComponent2 };
-  state = { id: 1 };
-}
-```
-
-There is an even more dynamic way to use `t-component`: its value can be an
-expression evaluating to an actual component class. In that case, this is the
-class that will be used to create the component:
-
-```js
-class A extends Component<any, any, any> {
-  static template = xml`<span>child a</span>`;
-}
-class B extends Component<any, any, any> {
-  static template = xml`<span>child b</span>`;
-}
-class App extends Component<any, any, any> {
-  static template = xml`<t t-component="myComponent" t-key="state.child"/>`;
-
-  state = { child: "a" };
-
-  get myComponent() {
-    return this.state.child === "a" ? A : B;
-  }
-}
-```
-
-In this example, the component `App` selects dynamically the concrete sub
-component class.
-
-Note that the `t-component` directive can only be used on `<t>` nodes.
+   ```xml
+   <div t-name="ParentComponent">
+     <SyncChild />
+     <AsyncChild t-asyncroot="1"/>
+   </div>
+   ```

 ### Error Handling

@@ -936,7 +1103,7 @@ from lifecycle hooks): the `catchError` hook.

 Whenever the `catchError` lifecycle hook is implemented, all errors coming from
 sub components rendering and/or lifecycle method calls will be caught and given
-to the `catchError` method. This allows us to properly handle the error, and to
+to the `catchError` method. This allow us to properly handle the error, and to
 not break the application.

 For example, here is how we could implement an `ErrorBoundary` component:
@@ -5,7 +5,7 @@ parts of the code. Owl has a very simple bus class, which manages subscriptions,
 triggering events, and callbacks.

 ```js
-const bus = new owl.core.EventBus();
+const bus = new owl.EventBus();

 bus.on("some-event", null, function(...args) {
  console.log(...args);
@@ -0,0 +1,275 @@
+# 🦉 Hooks 🦉
+
+## Content
+
+- [Overview](#overview)
+- [Example: Mouse Position](#example-mouse-position)
+- [Example: Autofocus](#example-autofocus)
+- [Reference](#reference)
+  - [One Rule](#one-rule)
+  - [`useState`](#usestate)
+  - [`onMounted`](#onmounted)
+  - [`onWillUnmount`](#onwillunmount)
+  - [`onWillPatch`](#onwillpatch)
+  - [`onPatched`](#onpatched)
+  - [`useRef`](#useref)
+  - [`useSubEnv`](#useSubEnv)
+
+## Overview
+
+Hooks were popularised by React as a way to solve the following issues:
+
+- help reusing stateful logic between components
+- help organizing code by feature in complex components
+- use state in functional components, without writing a class.
+
+Owl hooks serve the same purpose, except that they work for class components
+(note: React hooks do not work on class components, and maybe because of that,
+there seems to be the misconception that hooks are in opposition to class. This
+is clearly not true, as shown by Owl hooks).
+
+Hooks works beautifully with Owl components: they solve the problems mentioned
+above, and in particular, they are the perfect way to make your component
+reactive.
+
+## Example: mouse position
+
+Here is the classical example of a non trivial hook to track the mouse position.
+
+```js
+const { useState, onMounted, onWillUnmount } = owl.hooks;
+
+// We define here a custom behaviour: this hook tracks the state of the mouse
+// position
+function useMouse() {
+  const position = useState({ x: 0, y: 0 });
+
+  function update(e) {
+    position.x = e.clientX;
+    position.y = e.clientY;
+  }
+  onMounted(() => {
+    window.addEventListener("mousemove", update);
+  });
+  onWillUnmount(() => {
+    window.removeEventListener("mousemove", update);
+  });
+
+  return position;
+}
+
+// Main root component
+class App extends owl.Component {
+  static template = xml`
+    <div t-name="App">
+      <div>Mouse: <t t-esc="mouse.x"/>, <t t-esc="mouse.y"/></div>
+    </div>`;
+
+  // this hooks is bound to the 'mouse' property.
+  mouse = useMouse();
+}
+```
+
+Note that we use the prefix `use` for hooks, just like in React. This is just
+a convention.
+
+## Example: autofocus
+
+Hooks can be combined to create the desired effect. For example, the following
+hook combines the `useRef` hook with the `onPatched` and `onMounted` functions
+to create an easy way to focus an input whenever it appears in the DOM:
+
+```js
+function useAutofocus(name) {
+  let ref = useRef(name);
+  let isInDom = false;
+  function updateFocus() {
+    if (!isInDom && ref.el) {
+      isInDom = true;
+      ref.el.focus();
+    } else if (isInDom && !ref.el) {
+      isInDom = false;
+    }
+  }
+  onPatched(updateFocus);
+  onMounted(updateFocus);
+}
+```
+
+This hook takes the name of a valid `t-ref` directive, which should be present
+in the template. It then checks whenever the component is mounted or patched if
+the reference is not valid, and in this case, it will focus the node element.
+This hook can be used like this:
+
+```js
+class SomeComponent extends Component {
+  static template = xml`
+    <div>
+        <input />
+        <input t-ref="myinput"/>
+    </div>`;
+
+  constructor(...args) {
+    super(...args);
+    useAutofocus("myinput");
+  }
+}
+```
+
+## Reference
+
+### One rule
+
+There is only one rule: every hook for a component have to be called in the
+constructor (or in class fields):
+
+```js
+// ok
+class SomeComponent extends Component {
+  state = useState({ value: 0 });
+}
+
+// also ok
+class SomeComponent extends Component {
+  constructor(...args) {
+    super(...args);
+    this.state = useState({ value: 0 });
+  }
+}
+
+// not ok: this is executed after the constructor is called
+class SomeComponent extends Component {
+  async willStart() {
+    this.state = useState({ value: 0 });
+  }
+}
+```
+
+### `useState`
+
+The `useState` hook is certainly the most important hooks for Owl components:
+this is what enables component to be reactive, to react to state change.
+
+The `useState` hook has to be given an object or an array, and will return
+an observed version of it (using a `Proxy`).
+
+```javascript
+const { useState } = owl.hooks;
+
+class Counter extends owl.Component {
+  static template = xml`
+    <button t-on-click="increment">
+        Click Me! [<t t-esc="state.value"/>]
+    </button>`;
+
+  state = useState({ value: 0 });
+
+  increment() {
+    this.state.value++;
+  }
+}
+```
+
+### `onMounted`
+
+`onMounted` is not an user hook, but is a building block designed to help make useful
+abstractions. `onMounted` registers a callback, which will be called when the component
+is mounted (see example on top of this page).
+
+### `onWillUnmount`
+
+`onWillUnmount` is not an user hook, but is a building block designed to help make useful
+abstractions. `onWillUnmount` registers a callback, which will be called when the component
+is unmounted (see example on top of this page).
+
+
+### `onWillPatch`
+
+`onWillPatch` is not an user hook, but is a building block designed to help make useful
+abstractions. `onWillPatch` registers a callback, which will be called just
+before the component patched.
+
+### `onPatched`
+
+`onPatched` is not an user hook, but is a building block designed to help make useful
+abstractions. `onPatched` registers a callback, which will be called just
+after the component patched.
+
+### `useRef`
+
+The `useRef` hook is useful when we need a way to interact with some inside part
+of a component, rendered by Owl. It can work either on a DOM node, or on a component,
+tagged by the `t-ref` directive:
+
+```xml
+<div>
+    <div t-ref="someDiv"/>
+    <SubComponent t-ref="someComponent"/>
+</div>
+```
+
+In this example, the component will be able to access the `div` and the component
+`SubComponent` using the `useRef` hook:
+
+```js
+class Parent extends Component {
+  subRef = useRef("someComponent");
+  divRef = useRef("someDiv");
+
+  someMethod() {
+    // here, if component is mounted, refs are active:
+    // - this.divRef.el is the div HTMLElement
+    // - this.subRef.comp is the instance of the sub component
+  }
+}
+```
+
+As shown by the example above, html elements are accessed by using the `el`
+key, and components references are accessed with `comp`.
+
+Note: if used on a component, the reference will be set in the `refs`
+variable between `willPatch` and `patched`.
+
+The `t-ref` directive also accepts dynamic values with string interpolation
+(like the [`t-attf-`](qweb.md#dynamic-attributes) and
+`t-component` directives). For example,
+
+```xml
+<div t-ref="component_{{someCondition ? '1' : '2'}}"/>
+```
+
+Here, the references needs to be set like this:
+
+```js
+this.ref1 = useRef("component_1");
+this.ref2 = useRef("component_2");
+```
+
+References are only guaranteed to be active while the parent component is mounted.
+If this is not the case, accessing `el` or `comp` on it will return `null`.
+
+### `useSubEnv`
+
+The environment is sometimes useful to share some common information between
+all components.  But sometimes, we want to *scope* that knowledge to a subtree.
+
+For example, if we have a form view component, maybe we would like to make some
+`model` object available to all sub component, but not to the whole application.
+This is where the `useSubEnv` hook may be useful: it let a component add some
+information to the environment in a way that only the component and its children
+can access it:
+
+```js
+class FormComponent extends Component {
+  constructor(...args) {
+    super(...args);
+    const model = makeModel();
+    useSubEnv({ model });
+  }
+}
+```
+
+The `useSubEnv` takes one argument: an object which contains some key/value that
+will be added to the parent environment. Note that it will extend, not replace
+the parent environment.  And of course, the parent environment will not be
+affected.
@@ -1,132 +0,0 @@
-# 🦉 Testing Owl components 🦉
-
-## Content
-
- [Overview](#overview)
- [Unit Tests](#unit-tests)
-
-## Overview
-
-It is a good practice to test applications and components to ensure that they
-behave as expected. There are many ways to test a user interface: manual
-testing, integration testing, unit testing, ...
-
-In this section, we will discuss how to write unit tests for components, and
-how to debug them if necessary.
-
-## Unit Tests
-
-Writing unit tests for Owl components really depends on the testing framework
-used in a project. But usually, it involves the following steps:
-
- create a test file: for example `SomeComponent.test.js`,
- in that file, import the code for `SomeComponent`,
- add a test case:
-  - create a real DOM element to use as test fixture,
-  - create a test environment
-  - create an instance of `SomeComponent`, mount it to the fixture
-  - interact with the component and assert some properties.
-
-To help with this, it is useful to have a `helper.js` file that contains some
-common utility functions:
-
-```js
-export function makeTestFixture() {
-  let fixture = document.createElement("div");
-  document.body.appendChild(fixture);
-  return fixture;
-}
-
-export function nextTick() {
-  let requestAnimationFrame = owl.Component.scheduler.requestAnimationFrame;
-  return new Promise(function(resolve) {
-    setTimeout(() => requestAnimationFrame(() => resolve()));
-  });
-}
-
-export function makeTestEnv() {
-    // application specific. It needs a way to load actual templates
-    const templates = ...;
-
-    return {
-        qweb: new QWeb(templates),
-        ..., // each service can be mocked here
-    };
-}
-```
-
-With such a file, a typical test suite for Jest will look like this:
-
-```js
-// in SomeComponent.test.js
-import { SomeComponent } from "../../src/ui/SomeComponent";
-import { nextTick, makeTestFixture, makeTestEnv} from '../helpers';
-
-
-//------------------------------------------------------------------------------
-// Setup
-//------------------------------------------------------------------------------
-let fixture: HTMLElement;
-let env: Env;
-
-beforeEach(() => {
-  fixture = makeTestFixture();
-  env = makeTestEnv();
-  // we set here the default environment for each component created in the test
-  Component.env = env;
-});
-
-afterEach(() => {
-  fixture.remove();
-});
-
-//------------------------------------------------------------------------------
-// Tests
-//------------------------------------------------------------------------------
-describe("SomeComponent", () => {
-  test("component behaves as expected", async () => {
-    const props = {...}; // depends on the component
-    const comp = new SomeComponent(null, props);
-    await comp.mount(fixture);
-
-    // do some assertions
-    expect(...).toBe(...);
-
-    fixture.querySelector('button').click();
-    await nextTick();
-
-    // some other assertions
-    expect(...).toBe(...);
-  });
-});
-```
-
-Note that Owl does wait for the next animation frame to actually update the DOM.
-This is why it is necessary to wait with the `nextTick` (or other methods) to
-make sure that the DOM is up-to-date.
-
-It is sometimes useful to wait until Owl is completely done updating components
-(in particular, if we have a highly concurrent user interface). This next
-helper simply polls every 20ms the internal Owl task queue and returns a promise
-which resolves when it is empty:
-
-```js
-function afterUpdates() {
-  return new Promise((resolve, reject) => {
-    let timer = setTimeout(poll, 20);
-    let counter = 0;
-    function poll() {
-      counter++;
-      if (owl.Component.scheduler.tasks.length) {
-        if (counter > 10) {
-          reject(new Error("timeout"));
-        } else {
-          timer = setTimeout(poll);
-        }
-      } else {
-        resolve();
-      }
-    }
-  });
-}
-```
@@ -0,0 +1,20 @@
+# 🦉 Observer 🦉
+
+Owl need to be able to react to state changes. For example, whenever the state
+of a component is changed, we need to rerender it. To help with that, we have
+an Observer class. Its job is to observe some object state, and react to any
+change. To do that, it recursively replace all keys of the observed state by
+getters and setters.
+
+For example, this code will display `update` in the console:
+
+```javascript
+const observer = new owl.Observer();
+observer.notifyCB = () => console.log("update");
+const obj = observer.observe({ a: { b: 1 } });
+
+obj.a.b = 2;
+```
+
+The observer is implemented with the native `Proxy` object. Note that this
+means that it will not work on older browsers.
@@ -2,17 +2,8 @@

 ## Static Server

-Let us assume that we have a static server running somewhere. Let us start by
-adding an html page with a few extra files:
-
-```
-my-app/
-    index.html
-    app.css
-    app.js
-    owl-X.Y.Z.js
-    templates.xml
-```
+Let us assume that we have a static server running somewhere. We could then
+simply add an html page with a few extra files.

 ### HTML and CSS

@@ -64,7 +55,7 @@ To build an application (or a sub-part of an application), we need two things:

 - an environment: it is the global context in which we are working. It needs to
  contain a QWeb instance (preloaded with templates), and anything else that we
-  need. In practice, it could be used to contain some user session information, some
+  need. In practice, it could context some user session information, some
  configuration keys (for example, isMobile = true/false if we are in mobile mode).

 - a description of the user interface: there should be a root component, which can
@@ -85,7 +76,10 @@ const useState = owl.hooks.useState;

 class ClickCounter extends owl.Component {
  static template = "clickcounter";
-  state = useState({ value: 0 });
+  constructor() {
+    super(...arguments);
+    this.state = useState({ value: 0 });
+  }

  increment() {
    this.state.value++;
@@ -96,9 +90,11 @@ class ClickCounter extends owl.Component {
 // Application initialization
 //------------------------------------------------------------------------------
 async function start() {
-  const templates = await owl.utils.loadFile("templates.xml");
-  ClickCounter.env = { qweb: new owl.QWeb({ templates }) };
-  const counter = new ClickCounter();
+  const templates = await owl.utils.loadTemplates("templates.xml");
+  const env = {
+    qweb: new owl.QWeb(templates)
+  };
+  const counter = new ClickCounter(env);
  const target = document.getElementById("main");
  await counter.mount(target);
 }
@@ -1,9 +1,10 @@
-# 🦉 QWeb Templating Language🦉
+# 🦉 QWeb 🦉

 ## Content

 - [Overview](#overview)
 - [Directives](#directives)
+- [QWeb Engine](#qweb-engine)
 - [Reference](#reference)
  - [White Spaces](#white-spaces)
  - [Root Nodes](#root-nodes)
@@ -15,72 +16,156 @@
  - [Dynamic Attributes](#dynamic-attributes)
  - [Loops](#loops)
  - [Rendering Sub Templates](#rendering-sub-templates)
-  - [Translations](#translations)
  - [Debugging](#debugging)

 ## Overview

-[QWeb](https://www.odoo.com/documentation/13.0/reference/qweb.html) is the primary
-templating engine used by Odoo. It is based on the XML format, and used
+[QWeb](https://www.odoo.com/documentation/12.0/reference/qweb.html) is the primary templating engine used by Odoo. It is based on the XML format, and used
 mostly to generate HTML. In OWL, QWeb templates are compiled into functions that
 generate a virtual dom representation of the HTML.

+Template directives are specified as XML attributes prefixed with `t-`, for instance `t-if` for conditionals, with elements and other attributes being rendered directly.
+
+To avoid element rendering, a placeholder element `<t>` is also available, which executes its directive but doesn’t generate any output in and of itself.
+
 ```xml
 <div>
    <span t-if="somecondition">Some string</span>
    <ul t-else="1">
        <li t-foreach="messages" t-as="message">
-            <t t-esc="message"/>
+            <t t-esc="message">
        </li>
    </ul>
 </div>
 ```

-Template directives are specified as XML attributes prefixed with `t-`, for
-instance `t-if` for conditionals, with elements and other attributes being
-rendered directly.
+The QWeb class in the OWL project is an implementation of that specification
+with a few interesting points:

-To avoid element rendering, a placeholder element `<t>` is also available, which
-executes its directive but doesn’t generate any output in and of itself.
-
-We present in this section the templating language, including its Owl specific
-extensions.
+- it compiles templates into functions that output a virtual DOM instead of a
+  string. This is necessary for the component system.
+- it has a few extra directives: `t-component`, `t-on`, ...

 ## Directives

-For reference, here is a list of all standard QWeb directives:
+We present here a list of all standard QWeb directives:

-| Name                           | Description                                                    |
-| ------------------------------ | -------------------------------------------------------------- |
-| `t-esc`                        | [Outputting safely a value](#outputting-data)                  |
-| `t-raw`                        | [Outputting value, without escaping](#outputting-data)         |
-| `t-set`, `t-value`             | [Setting variables](#setting-variables)                        |
-| `t-if`, `t-elif`, `t-else`,    | [conditionally rendering](#conditionals)                       |
-| `t-foreach`, `t-as`            | [Loops](#loops)                                                |
-| `t-att`, `t-attf-*`, `t-att-*` | [Dynamic attributes](#dynamic-attributes)                      |
-| `t-call`                       | [Rendering sub templates](#rendering-sub-templates)            |
-| `t-debug`, `t-log`             | [Debugging](#debugging)                                        |
-| `t-translation`                | [Disabling the translation of a node](#translations)           |
-| `t-name`                       | [Defining a template (not really a directive)](qweb_engine.md) |
+| Name                           | Description                                                  |
+| ------------------------------ | ------------------------------------------------------------ |
+| `t-esc`                        | [Outputting safely a value](#outputting-data)                |
+| `t-raw`                        | [Outputting value, without escaping](#outputting-data)       |
+| `t-set`, `t-value`             | [Setting variables](#setting-variables)                      |
+| `t-if`, `t-elif`, `t-else`,    | [conditionally rendering](#conditionals)                     |
+| `t-foreach`, `t-as`            | [Loops](#loops)                                              |
+| `t-att`, `t-attf-*`, `t-att-*` | [Dynamic attributes](#dynamic-attributes)                    |
+| `t-call`                       | [Rendering sub templates](#rendering-sub-templates)          |
+| `t-debug`, `t-log`             | [Debugging](#debugging)                                      |
+| `t-name`                       | [Defining a template (not really a directive)](#qweb-engine) |

 The component system in Owl requires additional directives, to express various
 needs. Here is a list of all Owl specific directives:

-| Name                     | Description                                                                     |
-| ------------------------ | ------------------------------------------------------------------------------- |
-| `t-component`, `t-props` | [Defining a sub component](component.md#composition)                            |
-| `t-ref`                  | [Setting a reference to a dom node or a sub component](component.md#references) |
-| `t-key`                  | [Defining a key (to help virtual dom reconciliation)](#loops)                   |
-| `t-on-*`                 | [Event handling](component.md#event-handling)                                   |
-| `t-transition`           | [Defining an animation](animations.md#css-transitions)                          |
-| `t-slot`                 | [Rendering a slot](component.md#slots)                                          |
-| `t-model`                | [Form input bindings](component.md#form-input-bindings)                         |
+| Name                                                   | Description                                                                         |
+| ------------------------------------------------------ | ----------------------------------------------------------------------------------- |
+| `t-component`, `t-props`, `t-keepalive`, `t-asyncroot` | [Defining a sub component](component.md#composition)                                |
+| `t-ref`                                                | [Setting a reference to a dom node or a sub component](component.md#references)     |
+| `t-key`                                                | [Defining a key (to help virtual dom reconciliation)](component.md#t-key-directive) |
+| `t-on-*`                                               | [Event handling](component.md#event-handling)                                       |
+| `t-transition`                                         | [Defining an animation](animations.md#css-transitions)                              |
+| `t-slot`                                               | [Rendering a slot](component.md#slots)                                              |
+| `t-model`                                              | [Form input bindings](component.md#form-input-bindings)                             |
+
+## QWeb Engine
+
+This section is about the javascript code that implements the `QWeb` specification.
+Owl exports a `QWeb` class in `owl.QWeb`. To use it, it just needs to be
+instantiated:
+
+```js
+const qweb = new owl.QWeb();
+```
+
+It's API is quite simple:
+
+- **`constructor(data)`**: constructor. Takes an optional string to add initial
+  templates (see `addTemplates` for more information on format of the string).
+
+  ```js
+  const qweb = new owl.QWeb(TEMPLATES);
+  ```
+
+- **`addTemplate(name, xmlStr, allowDuplicate)`**: add a specific template.
+
+  ```js
+  qweb.addTemplate("mytemplate", "<div>hello</div>");
+  ```
+
+  If the optional `allowDuplicate` is set to `true`, then `QWeb` will simply return whenever a template is added for a second time. Otherwise, `QWeb` will crash.
+
+- **`addTemplates(xmlStr)`**: add a list of templates (identified by `t-name`
+  attribute).
+
+  ```js
+  const TEMPLATES = `
+    <templates>
+      <div t-name="App" class="main">main</div>
+      <div t-name="OtherComponent">other component</div>
+    </templates>`;
+  qweb.addTemplates(TEMPLATES);
+  ```
+
+- **`render(name, context, extra)`**: renders a template. This returns a `vnode`,
+  which is a virtual representation of the DOM (see [vdom doc](vdom.md)).
+
+  ```js
+  const vnode = qweb.render("App", component);
+  ```
+
+- **`renderToString(name, context)`**: renders a template, but returns an html
+  string.
+
+  ```js
+  const str = qweb.renderToString("someTemplate", somecontext);
+  ```
+
+- **`registerTemplate(name, template)`**: static function to register an global
+  QWeb template. This is useful for commonly used components accross the
+  application, and for making a template available to an application without
+  having a reference to the actual QWeb instance.
+
+  ```js
+  QWeb.registerTemplate("mytemplate", `<div>some template`);
+  ```
+
+- **`registerComponent(name, Component)`**: static function to register an OWL Component
+  to QWeb's global registry. Globally registered Components can be used in
+  templates (see the `t-component` directive). This is useful for commonly used
+  components accross the application.
+
+  ```js
+  class Dialog extends owl.Component { ... }
+  QWeb.registerComponent("Dialog", Dialog);
+
+  ...
+
+  class ParentComponent extends owl.Component { ... }
+  qweb.addTemplate("ParentComponent", "<div><Dialog/></div>");
+  ```
+
+In some way, a `QWeb` instance is the core of an Owl application. It is the only
+mandatory element of an [environment](component.md#environment). As such, it
+has an extra responsability: it can act as an event bus for internal communication
+between Owl classes. This is the reason why `QWeb` actually extends [EventBus](event_bus.md).

 ## Reference

+We define in this section the specification of how `QWeb` templates should be
+rendered. Note that we only document here the standard QWeb specification. Owl
+specific extensions are documented in various other parts of the documentation.
+
 ### White Spaces

-White spaces in a template are handled in a special way:
+White spaces in a templates are handled in a special way:

 - consecutive whitespaces are always condensed to a single whitespace
 - if a whitespace-only text node contains a linebreak, it is ignored
@@ -115,14 +200,14 @@ root nodes.
 ### Expression Evaluation

 QWeb expressions are strings that will be processed at compile time. Each variable in
-the javascript expression will be replaced with a lookup in the context (so, the
+the javascript expression will be replaced by a lookup in the context (so, the
 component). For example, `a + b.c(d)` will be converted into:

 ```js
 context["a"] + context["b"].c(context["d"]);
 ```

-It is useful to explain the various rules that apply on these expressions:
+It is useful to explain the various rules that applies on these expressions:

 1. it should be a simple expression which returns a value. It cannot be a statement.

@@ -148,14 +233,14 @@ It is useful to explain the various rules that apply on these expressions:
 3. it can use a few special operators to avoid using symbols such as `<`, `>`,
   `&` or `|`. This is useful to make sure that we still write valid XML.

-   | Word  | replaced with |
-   | ----- | ------------- |
-   | `and` | `&&`          |
-   | `or`  | `\|\|`        |
-   | `gt`  | `>`           |
-   | `gte` | `>=`          |
-   | `lt`  | `<`           |
-   | `lte` | `<=`          |
+   | Word  | will be replaced by |
+   | ----- | ------------------- |
+   | `and` | `&&`                |
+   | `or`  | `\|\|`              |
+   | `gt`  | `>`                 |
+   | `gte` | `>=`                |
+   | `lt`  | `<`                 |
+   | `lte` | `<=`                |

   So, one can write this:

@@ -200,11 +285,6 @@ rendered with the value `value` set to `<span>foo</span>` in the rendering conte
 <p><span>foo</span></p>
 ```

-Note that since the content of the expression is not known beforehand, the `t-raw`
-directive has to parse the html (and convert it to a virtual dom structure) for
-each rendering. So, it will be much slower than a regular template. It is
-therefore advised to limit the use of `t-raw` whenever possible.
-
 ### Setting Variables

 QWeb allows creating variables from within the template, to memoize a computation (to use it multiple times), give a piece of data a clearer name, ...
@@ -304,25 +384,14 @@ If an expression evaluates to a falsy value, it will not be set at all:
 <div t-att-foo="false"/>  <!-- result: <div></div> -->
 ```

-It is sometimes convenient to format an attribute with string interpolation. In
-that case, the `t-attf-` directive can be used. It is useful when we need to mix
-literal and dynamic elements, such as css classes.
+There is another way to format a string attribute: the `t-attf-` directive. With
+it, you get string interpolation:

 ```xml
 <div t-attf-foo="a {{value1}} is {{value2}} of {{value3}} ]"/>
 <!-- result if values are set to 1,2 and 3: <div foo="a 0 is 1 of 2 ]"></div> -->
 ```

-If we need completely dynamic attribute names, then there is an additional
-directive: `t-att`, which takes either an object (with keys mapping to their
-values) or a pair `[key, value]`. For example:
-
-```xml
-<div t-att="{'a': 1, 'b': 2}"/> <!-- result: <div a="1" b="2"></div> -->
-
-<div t-att="['a', 'b']"/> <!-- <div a="b"></div> -->
-```
-
 ### Loops

 QWeb has an iteration directive `t-foreach` which take an expression returning the
@@ -357,7 +426,7 @@ is equivalent to the previous example.
 or an object (the current item will be the current key).

 In addition to the name passed via t-as, `t-foreach` provides a few other
-variables for various data points (note: `$as` will be replaced with the name
+variables for various data points (note: `$as` will be replaced by the name
 passed to `t-as`):

 - `$as_value`: the current iteration value, identical to `$as` for lists and
@@ -375,83 +444,19 @@ the context of the `t-foreach`, the value is copied at the end of the foreach
 into the global context.

 ```xml
-<t t-set="existing_variable" t-value="false"/>
+<t t-set="existing_variable" t-value="False"/>
 <!-- existing_variable now False -->

 <p t-foreach="Array(3)" t-as="i">
-    <t t-set="existing_variable" t-value="true"/>
-    <t t-set="new_variable" t-value="true"/>
-    <!-- existing_variable and new_variable now true -->
+    <t t-set="existing_variable" t-value="True"/>
+    <t t-set="new_variable" t-value="True"/>
+    <!-- existing_variable and new_variable now True -->
 </p>

-<!-- existing_variable always true -->
+<!-- existing_variable always True -->
 <!-- new_variable undefined -->
 ```

-Even though Owl tries to be as declarative as possible, the DOM does not fully
-expose its state declaratively in the DOM tree. For example, the scrolling state,
-the current user selection, the focused element or the state of an input are not
-set as attribute in the DOM tree. This is why we use a virtual dom
-algorithm to keep the actual DOM node as much as possible.
-
-However, in some situations, this is not enough, and we need to help Owl decide
-if an element is actually the same, or is a different element with the same
-properties.
-
-Consider the following situation: we have a list of two items `[{text: "a"}, {text: "b"}]`
-and we render them in this template:
-
-```xml
-<p t-foreach="items" t-as="item"><t t-esc="item.text"/></p>
-```
-
-The result will be two `<p>` tags with text `a` and `b`. Now, if we swap them,
-and rerender the template, Owl needs to know what the intent is:
-
- should Owl actually swap the DOM nodes,
- or should it keep the DOM nodes, but with an updated text content?
-
-This might look trivial, but it actually matters. These two possibilities lead
-to different results in some cases. For example, if the user selected the text
-of the first `p`, swapping them will keep the selection while updating the
-text content will not.
-
-There are many other cases where this is important: `input` tags with their
-value, css classes and animations, scroll position...
-
-So, the `t-key` directive is used to give an identity to an element. It allows
-Owl to understand if different elements of a list are actually different or not.
-
-The above example could be modified by adding an ID: `[{id: 1, text: "a"}, {id: 2, text: "b"}]`.
-Then, the template could look like this:
-
-```xml
-<p t-foreach="items" t-as="item" t-key="item.id"><t t-esc="item.text"/></p>
-```
-
-The `t-key` directive is useful for lists (`t-foreach`). A key should be
-a unique number or string (objects will not work: they will be cast to the
-`"[object Object]"` string, which is obviously not unique).
-
-Also, the key can be set on a `t` tag or on its children. The following variations
-are all equivalent:
-
-```xml
-<p t-foreach="items" t-as="item" t-key="item.id">
-  <t t-esc="item.text"/>
-</p>
-
-<t t-foreach="items" t-as="item" t-key="item.id">
-  <p t-esc="item.text"/>
-</t>
-
-<t t-foreach="items" t-as="item">
-  <p t-key="item.id" t-esc="item.text"/>
-</t>
-```
-
-If there is no `t-key` directive, Owl will use the index as a default key.
-
 ### Rendering Sub Templates

 QWeb templates can be used for top level rendering, but they can also be used
@@ -500,30 +505,6 @@ will result in :
 </div>
 ```

-This can be used to define variables scoped to a sub template:
-
-```xml
-<t t-call="other-template">
-    <t t-set="var" t-value="1"/>
-</t>
-<!-- "var" does not exist here -->
-```
-
-### Translations
-
-By default, QWeb specify that templates should be translated. If this behaviour
-is not wanted, there is a `t-translation` directive which can turn off
-translations (if it is set to the `off` value), with the following rules:
-
- each text node will be replaced with its translation,
- each of the following attribute values will be translated as well: `title`,
-  `placeholder`, `label` and `alt`,
- translating text nodes can be disabled with the special attribute `t-translation`,
-  if its value is `off`.
-
-See [here](qweb_engine.md#translations) for more information on how to setup a
-translate function in Owl QWeb.
-
 ### Debugging

 The javascript QWeb implementation provides two useful debugging directives:
@@ -545,4 +526,4 @@ will stop execution if the browser dev tools are open.
 <t t-log="foo"/>
 ```

-will print 42 to the console.
+will print 42 to the console
@@ -1,77 +1,65 @@
 # 🦉 OWL Documentation 🦉

+## Owl Content
+
+Owl is a javascript library that contains some core classes and function to help
+build applications. Here is a complete representation of its content:
+
+```
+owl
+    Component
+    QWeb
+    useState
+    core
+        EventBus
+        Observer
+    hooks
+        onMounted
+        onWillUnmount
+        onWillPatch
+        onPatched
+        useState
+        useRef
+        useSubEnv
+    router
+        Link
+        RouteComponent
+        Router
+    store
+        Store
+        ConnectedComponent
+    tags
+        xml
+    utils
+        debounce
+        escape
+        loadJS
+        loadTemplates
+        whenReady
+```
+
+Note that for convenience, the `useState` hook is also exported at the root of the `owl` object.
+
 ## Reference

- [Animations](reference/animations.md)
- [Component](reference/component.md)
- [Concurrency Model](reference/concurrency_model.md)
- [Configuration](reference/config.md)
- [Context](reference/context.md)
- [Environment](reference/environment.md)
- [Event Bus](reference/event_bus.md)
- [Hooks](reference/hooks.md)
- [Miscellaneous Components](reference/misc.md)
- [Observer](reference/observer.md)
- [Props](reference/props.md)
- [Props Validation](reference/props_validation.md)
- [QWeb Templating Language](reference/qweb_templating_language.md)
- [QWeb Engine](reference/qweb_engine.md)
- [Router](reference/router.md)
- [Store](reference/store.md)
- [Tags](reference/tags.md)
- [Utils](reference/utils.md)
+- [Animations](animations.md)
+- [Component](component.md)
+- [Event Bus](event_bus.md)
+- [Hooks](hooks.md)
+- [Observer](observer.md)
+- [QWeb](qweb.md)
+- [Router](router.md)
+- [Store](store.md)
+- [Tags](tags.md)
+- [Utils](utils.md)
+- [Virtual DOM](vdom.md)

 ## Learning Resources

- [Quick Start: create an (almost) empty Owl application](learning/quick_start.md)
- [Tutorial: create a TodoList application](learning/tutorial_todoapp.md)
- [Testing Owl components](learning/testing_components.md)
+- [Quick Start](quick_start.md)

 ## Miscellaneous

 - [Comparison with React/Vue](comparison.md)
 - [Tooling](tooling.md)
 - [Templates to start Owl applications (external link)](https://github.com/ged-odoo/owl-templates)
-
-## Architecture
-
-This section explains in more detail the inner workings of Owl. It is targeted
-for developers working on Owl itself.
-
- [Virtual DOM](architecture/vdom.md)
- [Rendering](architecture/rendering.md)
-
-## Owl Content
-
-Here is a complete visual representation of everything exported by the `owl`
-global object (so, for example, `Component` is available at `owl.Component`,
-and `EventBus` is exported as `owl.core.EventBus`):
-
-```
-Component                               misc
-Context                                     AsyncRoot
-QWeb                                        Portal
-Store                                   router
-useState                                    Link
-config                                      RouteComponent
-    mode                                    Router
-core                                    tags
-    EventBus                                xml
-    Observer                            utils
-hooks                                       debounce
-    onWillStart                             escape
-    onMounted                               loadJS
-    onWillUpdateProps                       loadFile
-    onWillPatch                             shallowEqual
-    onPatched                               whenReady
-    onWillUnmount
-    useContext
-    useState
-    useRef
-    useSubEnv
-    useStore
-    useDispatch
-    useGetters
-```
-
-Note that for convenience, the `useState` hook is also exported at the root of the `owl` object.
@@ -1,183 +0,0 @@
-# 🦉 Concurrency Model 🦉
-
-## Content
-
- [Overview](#overview)
- [Rendering Components](#rendering-components)
- [Semantics](#semantics)
- [Asynchronous Rendering](#asynchronous-rendering)
-
-## Overview
-
-Owl was designed from the very beginning with asynchronous components. This comes
-from the `willStart` and the `willUpdateProps` lifecycle hooks. With these
-methods, it is possible to build complex highly concurrent applications.
-
-Owl concurrent mode has several benefits: it makes it possible to delay the
-rendering until some asynchronous operation is complete, it makes it possible
-to lazy load libraries, while keeping the previous screen completely functional.
-It is also good for performance reasons: Owl uses it to only apply the result of
-many different renderings only once in an animation frame. Owl can cancel
-a rendering that is no longer relevant, restart it, reuse it in some cases.
-
-But even though using concurrency is quite simple (and is the default behaviour),
-asynchrony is difficult, because it introduces an additional dimension that
-vastly increase the complexity of an application. This section will explain
-how Owl manages this complexity, how concuurent rendering works in a general way.
-
-## Rendering Components
-
-The word _rendering_ is a little vague, so, let us explain more precisely the
-process by which Owl components are displayed on a screen.
-
-When a component is mounted or updated, a new rendering is started. It has
-two phases: _virtual rendering_ and _patching_.
-
-### Virtual rendering
-
-This phase represent the process of rendering a template, in memory, which create a virtual representation of the desired component html). The output of this phase is a
-virtual DOM.
-
-It is asynchronous: each subcomponents needs to either be created (so, `willStart`
-will need to be called), or updated (which is done with the `willUpdateProps`
-method). This is completely a recursive process: a component is the root of a
-component tree, and each sub component needs to be (virtually) rendered.
-
-### Patching
-
-Once a rendering is complete, it will be applied on the next animation frame.
-This is done synchronously: the whole component tree is patched to the real
-DOM.
-
-## Semantics
-
-We give here an informal description of the way components are created/updated
-in an application. Here, ordered lists describe actions that are executed
-sequentially, bullet lists describe actions that are executed in parallel.
-
-**Scenario 1: initial rendering** Imagine we want to render the following component tree:
-
-```
-        A
-       / \
-      B   C
-         / \
-        D   E
-```
-
-Here is what happen whenever we mount the root
-component (with some code like `app.mount(document.body)`).
-
-1. `willStart` is called on `A`
-
-2. when it is done, template `A` is rendered.
-
-   - component `B` is created
-     1. `willStart` is called on `B`
-     2. template `B` is rendered
-   - component `C` is created
-     1. `willStart` is called on `C`
-     2. template `C` is rendered
-        - component `D` is created
-          1. `willStart` is called on `D`
-          2. template `D` is rendered
-        - component `E` is created
-          1. `willStart` is called on `E`
-          2. template `E` is rendered
-
-3. each components are patched into a detached DOM element, in the following order:
-   `E`, `D`, `C`, `B`, `A`. (so the actual full DOM tree is created
-   in one pass)
-
-4. the component `A` root element is actually appended to `document.body`
-
-5. The method `mounted` is called recursively on all components in the following
-   order: `E`, `D`, `C`, `B`, `A`.
-
-**Scenario 2: rerendering a component**. Now, let's assume that the user clicked on some
-button in `C`, and this results in a state update, which is supposed to:
-
- update `D`,
- remove `E`,
- add new component `F`.
-
-So, the component tree should look like this:
-
-```
-        A
-       / \
-      B   C
-         / \
-        D   F
-```
-
-Here is what Owl will do:
-
-1. because of a state change, the method `render` is called on `C`
-2. template `C` is rendered again
-
-   - component `D` is updated:
-     1. hook `willUpdateProps` is called on `D` (async)
-     2. template `D` is rerendered
-   - component `F` is created:
-     1. hook `willStart` is called on `E` (async)
-     2. template `F` is rendered
-
-3. `willPatch` hooks are called recursively on components `C`, `D` (not on `F`,
-   because it is not mounted yet)
-
-4. components `F`, `D` are patched in that order
-
-5. component `C` is patched, which will cause recursively:
-
-   1. `willUnmount` hook on `E`
-   2. destruction of `E`,
-
-6. `mounted` hook is called on `F`, `patched` hooks are called on `D`, `C`
-
-Tags are very small helpers to make it easy to write inline templates. There is
-only one currently available tag: `xml`, but we plan to add other tags later,
-such as a `css` tag, which will be used to write [single file components](../tooling.md#single-file-component).
-
-### Asynchronous Rendering
-
-Working with asynchronous code always adds a lot of complexity to a system. Whenever
-different parts of a system are active at the same time, one needs to think
-carefully about all possible interactions. Clearly, this is also true for Owl
-components.
-
-There are two different common problems with Owl asynchronous rendering model:
-
- any component can delay the rendering (initial and subsequent) of the whole
-  application
- for a given component, there are two independant situations that will trigger an
-  asynchronous rerendering: a change in the state, or a change in the props.
-  These changes may be done at different times, and Owl has no way of knowing
-  how to reconcile the resulting renderings.
-
-Here are a few tips on how to work with asynchronous components:
-
-1. Minimize the use of asynchronous components!
-2. Maybe move the asynchronous logic in a store, which then triggers (mostly)
-   synchronous renderings
-3. Lazy loading external libraries is a good use case for async rendering. This
-   is mostly fine, because we can assume that it will only takes a fraction of a
-   second, and only once (see [`owl.utils.loadJS`](utils.md#loadjs))
-4. For all the other cases, the [`AsyncRoot`](misc.md#asyncroot) component is there to help you. When
-   this component is met, a new rendering
-   sub tree is created, such that the rendering of that component (and its
-   children) is not tied to the rendering of the rest of the interface. It can
-   be used on an asynchronous component, to prevent it from delaying the
-   rendering of the whole interface, or on a synchronous one, such that its
-   rendering isn't delayed by other (asynchronous) components. Note that this
-   directive has no effect on the first rendering, but only on subsequent ones
-   (triggered by state or props changes).
-
-   ```xml
-   <div t-name="ParentComponent">
-     <SyncChild />
-     <AsyncRoot>
-        <AsyncChild/>
-     </AsyncRoot>
-   </div>
-   ```
@@ -1,27 +0,0 @@
-# 🦉 Config 🦉
-
-The Owl framework is designed to work in many situations. However, it is
-sometimes necessary to customize some behaviour. This is done by using the
-global `config` object. It currently has one key:
-
- [`mode`](#mode).
-
-## Mode
-
-By default, Owl is in _production_ mode, this means that it will try to do its
-job fast, and skip some expensive operations. However, it is sometimes necessary
-to have better information on what is going on, this is the purpose
-of the `dev` mode.
-
-Owl has a mode flag, in `owl.config.mode`. Its default value is `prod`, but
-it can be set to `dev`:
-
-```js
-owl.config.mode = "dev";
-```
-
-Note that templates compiled with the `prod` settings will not be recompiled.
-So, changing this setting is best done at startup.
-
-An important job done by the `dev` mode is to validate props for each component
-creation and update. Also, extra props will cause an error.
@@ -1,105 +0,0 @@
-# 🦉 Context 🦉
-
-## Content
-
- [Overview](#overview)
- [Example](#example)
- [Reference](#reference)
-  - [`Context`](#context)
-  - [`useContext`](#usecontext)
-
-## Overview
-
-The `Context` object provides a way to share data between an arbitrary number
-of components. Usually, data is passed from a parent to its children component,
-but when we have to deal with some mostly global information, this can be
-annoying, since each component will need to pass the information to each children,
-even though some or most of them will not use the information.
-
-With a `Context` object, each component can subscribe (with the `useContext` hook)
-to its state, and will be updated whenever the context state is updated.
-
-## Example
-
-Assume that we have an application with various components which needs to render
-differently depending on the size of the device. Here is how we could proceed
-to make sure that the information is properly shared. First, let us create a
-context, and add it to the environment:
-
-```js
-const deviceContext = new Context({ isMobile: true });
-App.env.deviceContext = deviceContext;
-```
-
-If we want to make it completely responsive, we need to update its value whenever
-the size of the screen is updated:
-
-```js
-const isMobile = () => window.innerWidth <= 768;
-window.addEventListener(
-  "resize",
-  owl.utils.debounce(() => {
-    const state = deviceContext.state;
-    if (state.isMobile !== isMobile()) {
-      state.isMobile = !state.isMobile;
-    }
-  }, 15)
-);
-```
-
-Then, each component that want can subscribe and render differently depending on the
-fact that we are in a mobile or desktop mode.
-
-```js
-class SomeComponent extends Component {
-  static template = xml`
-    <div>
-      <t t-if=device.isMobile>
-          some simplified user interface
-      </t>
-      <t t-else="1">
-          a more advanced user interface
-      </t>
-    </div>`;
-  device = useContext(this.env.deviceContext);
-}
-```
-
-## Reference
-
-### `Context`
-
-A `Context` object should be created with a state object:
-
-```js
-const someContext = new Context({ some: "key" });
-```
-
-Its state is now available in the `state` key:
-
-```js
-someContext.state.some = "other key";
-```
-
-This is the way some global code (such as the responsive code above) should
-read and update the context state. However, components should not ever read the
-context state directly from the context, they should instead use the `useContext`
-hook to properly register themselves to state changes.
-
-Note that the `Context` hook is different from the React version. For example,
-there is no concept of provider/consumer. So, the `Context` feature does not
-by itself allow the use of a different context state depending on the component
-place in the component tree. However, this functionality can be obtained, if
-necessary, with the use of sub environment.
-
-### `useContext`
-
-The `useContext` hook is the normal way for a component to register themselve
-to context state changes. The `useContext` method returns the context state:
-
-```js
-device = useContext(this.env.deviceContext);
-```
-
-It is a simple observed state (with an owl `Observer`), which contains the shared
-information.
@@ -1,127 +0,0 @@
-# 🦉 Environment 🦉
-
-## Content
-
- [Overview](#overview)
- [Setting an Environment](#setting-an-environment)
- [Using a sub environment](#using-a-sub-environment)
- [Content of an Environment](#content-of-an-environment)
-
-## Overview
-
-An environment is an object which contains a [`QWeb` instance](qweb_engine.md). Whenever
-a root component is created, it is assigned an environment (see
-[below](#setting-an-environment) for more info on this). This environment is
-then automatically given to each sub component (and accessible in the `this.env`
-property).
-
-```
-    Root
-    /  \
-   A    B
-```
-
-This way, all components share the same `QWeb` instance. Owl internally requires
-that the environment has a `qweb` key which maps to a
-[`QWeb`](qweb_engine.md) instance. This is the QWeb instance that will be used to
-render each templates in this specific component tree. Note that if no `QWeb`
-instance is provided, Owl will simply generate it on the fly.
-
-The environment is mostly static. Each application is free to add anything to
-the environment, which is very useful, since this can be accessed by each sub
-component.
-
-## Setting an environment
-
-An Owl application needs an [environment](environment.md) to be executed. The
-environment has an important key: the [QWeb](qweb_engine.md) instance, which will render
-all templates.
-
-Whenever a root component `App` is mounted, Owl will setup a valid environment by
-following the next steps:
-
- take the `env` object defined on `App.env` (if no `env` was explicitely setup,
-  this will be return the empty `env` object defined on `Component`)
- if `env.qweb` is not set, then Owl will create a `QWeb` instance.
-
-The correct way to customize an environment is to simply set it up on the root
-component class, before the first component is created:
-
-```js
-App.env = {
-    _t: myTranslateFunction,
-    user: {...},
-    services: {
-        ...
-    },
-};
-const app = new App();
-app.mount(document.body);
-```
-
-It is also possible to simply share an environment between all root components,
-by simply doing this:
-
-```js
-Component.env = myEnv; // will be the default env for all components
-```
-
-Note that this environment is the global owl environment for an application. The
-next section explains how to extend an environment for a specific sub component
-and its children.
-
-## Using a sub environment
-
-It is sometimes useful to add one (or more) specific keys to the environment,
-from the perspective of a specific component and its children. In that case, the
-solution presented above will not work, since it sets the global environment.
-
-There is a hook for this situation: [`useSubEnv`](hooks.md#usesubenv).
-
-```js
-class FormComponent extends Component {
-  constructor(parent, props) {
-    super(parent, props);
-    useSubEnv({ myKey: someValue });
-  }
-}
-```
-
-## Content of an Environment
-
-Some good use cases for additional keys in the environment are:
-
- some configuration keys,
- session information,
- generic services (such as doing rpcs, or accessing local storage).
-
-Doing it this way means that components are easily testable: we can simply
-create a test environment with mock services.
-
-For example:
-
-```js
-async function myEnv() {
-  const templates = await loadTemplates();
-  const qweb = new QWeb({ templates });
-  const session = getSession();
-
-  return {
-    _t: myTranslateFunction,
-    session: session,
-    qweb: qweb,
-    services: {
-      localStorage: localStorage,
-      rpc: rpc
-    },
-    debug: false,
-    inMobileMode: true
-  };
-}
-
-async function start() {
-  App.env = await myEnv();
-  const app = new App();
-  await app.mount(document.body);
-}
-```
@@ -1,435 +0,0 @@
-# 🦉 Hooks 🦉
-
-## Content
-
- [Overview](#overview)
- [Example: Mouse Position](#example-mouse-position)
- [Example: Autofocus](#example-autofocus)
- [Reference](#reference)
-  - [One Rule](#one-rule)
-  - [`useState`](#usestate)
-  - [`onMounted`](#onmounted)
-  - [`onWillUnmount`](#onwillunmount)
-  - [`onWillPatch`](#onwillpatch)
-  - [`onPatched`](#onpatched)
-  - [`onWillStart`](#onwillstart)
-  - [`onWillUpdateProps`](#onwillupdateprops)
-  - [`useContext`](#usecontext)
-  - [`useRef`](#useref)
-  - [`useSubEnv`](#usesubenv)
-  - [`useStore`](#usestore)
-  - [`useDispatch`](#usedispatch)
-  - [`useGetters`](#usegetters)
-  - [Making customized hooks](#making-customized-hooks)
-
-## Overview
-
-Hooks were popularised by React as a way to solve the following issues:
-
- help reusing stateful logic between components
- help organizing code by feature in complex components
- use state in functional components, without writing a class.
-
-Owl hooks serve the same purpose, except that they work for class components
-(note: React hooks do not work on class components, and maybe because of that,
-there seems to be the misconception that hooks are in opposition to class. This
-is clearly not true, as shown by Owl hooks).
-
-Hooks work beautifully with Owl components: they solve the problems mentioned
-above, and in particular, they are the perfect way to make your component
-reactive.
-
-## Example: mouse position
-
-Here is the classical example of a non trivial hook to track the mouse position.
-
-```js
-const { useState, onMounted, onWillUnmount } = owl.hooks;
-
-// We define here a custom behaviour: this hook tracks the state of the mouse
-// position
-function useMouse() {
-  const position = useState({ x: 0, y: 0 });
-
-  function update(e) {
-    position.x = e.clientX;
-    position.y = e.clientY;
-  }
-  onMounted(() => {
-    window.addEventListener("mousemove", update);
-  });
-  onWillUnmount(() => {
-    window.removeEventListener("mousemove", update);
-  });
-
-  return position;
-}
-
-// Main root component
-class App extends owl.Component {
-  static template = xml`
-    <div t-name="App">
-      <div>Mouse: <t t-esc="mouse.x"/>, <t t-esc="mouse.y"/></div>
-    </div>`;
-
-  // this hooks is bound to the 'mouse' property.
-  mouse = useMouse();
-}
-```
-
-Note that we use the prefix `use` for hooks, just like in React. This is just
-a convention.
-
-## Example: autofocus
-
-Hooks can be combined to create the desired effect. For example, the following
-hook combines the `useRef` hook with the `onPatched` and `onMounted` functions
-to create an easy way to focus an input whenever it appears in the DOM:
-
-```js
-function useAutofocus(name) {
-  let ref = useRef(name);
-  let isInDom = false;
-  function updateFocus() {
-    if (!isInDom && ref.el) {
-      isInDom = true;
-      ref.el.focus();
-    } else if (isInDom && !ref.el) {
-      isInDom = false;
-    }
-  }
-  onPatched(updateFocus);
-  onMounted(updateFocus);
-}
-```
-
-This hook takes the name of a valid `t-ref` directive, which should be present
-in the template. It then checks whenever the component is mounted or patched if
-the reference is not valid, and in this case, it will focus the node element.
-This hook can be used like this:
-
-```js
-class SomeComponent extends Component {
-  static template = xml`
-    <div>
-        <input />
-        <input t-ref="myinput"/>
-    </div>`;
-
-  constructor(...args) {
-    super(...args);
-    useAutofocus("myinput");
-  }
-}
-```
-
-## Reference
-
-### One rule
-
-There is only one rule: every hook for a component has to be called in the
-constructor (or in class fields):
-
-```js
-// ok
-class SomeComponent extends Component {
-  state = useState({ value: 0 });
-}
-
-// also ok
-class SomeComponent extends Component {
-  constructor(...args) {
-    super(...args);
-    this.state = useState({ value: 0 });
-  }
-}
-
-// not ok: this is executed after the constructor is called
-class SomeComponent extends Component {
-  async willStart() {
-    this.state = useState({ value: 0 });
-  }
-}
-```
-
-As you can see, the `useState` hook does not need to be given a reference to
-the component. This is possible because there is a way to get a reference to the
-current component: the `Component.current` static property is the reference to the
-component instance that is currently being created.
-
-Hooks need to be called in the constructor to ensure that this reference is
-properly set. This is also a good thing for performance reasons (Owl can use
-this to optimize its implementation), and for a clean architecture (this makes
-it easier for developers to understand what is really happening in a component).
-
-### `useState`
-
-The `useState` hook is certainly the most important hook for Owl components:
-this is what allows a component to be reactive, to react to state change.
-
-The `useState` hook has to be given an object or an array, and will return
-an observed version of it (using a `Proxy`).
-
-```javascript
-const { useState } = owl.hooks;
-
-class Counter extends owl.Component {
-  static template = xml`
-    <button t-on-click="increment">
-        Click Me! [<t t-esc="state.value"/>]
-    </button>`;
-
-  state = useState({ value: 0 });
-
-  increment() {
-    this.state.value++;
-  }
-}
-```
-
-It is important to remember that `useState` only works with objects or arrays. It
-is necessary, since Owl needs to react to a change in state.
-
-### `onMounted`
-
-`onMounted` is not a user hook, but is a building block designed to help make useful
-abstractions. `onMounted` registers a callback, which will be called when the component
-is mounted (see example on top of this page).
-
-### `onWillUnmount`
-
-`onWillUnmount` is not a user hook, but is a building block designed to help make useful
-abstractions. `onWillUnmount` registers a callback, which will be called when the component
-is unmounted (see example on top of this page).
-
-### `onWillPatch`
-
-`onWillPatch` is not a user hook, but is a building block designed to help make useful
-abstractions. `onWillPatch` registers a callback, which will be called just
-before the component patched.
-
-### `onPatched`
-
-`onPatched` is not a user hook, but is a building block designed to help make useful
-abstractions. `onPatched` registers a callback, which will be called just
-after the component patched.
-
-### `onWillStart`
-
-`onWillStart` is an asynchronous hook. This means that the function registered
-in the hook will be run just before the component is first rendered and can return a
-promise, to express the fact that it is an asynchronous operation.
-
-Note that if there are more than one `onWillStart` registered callback, then they
-will all be run in parallel.
-
-It can be used to load some initial data. For example, the following hook will
-automatically load some data from the server, and return an object that will
-be ready whenever the component is rendered:
-
-```js
-function useLoader() {
-  const component = Component.current;
-  const record = useState({});
-  onWillStart(async () => {
-    const recordId = component.props.id;
-    Object.assign(record, await fetchSomeRecord(recordId));
-  });
-  return record;
-}
-```
-
-Note that this example does not update the record value whenever props are
-updated. For that situation, we need to use the `onWillUpdateProps` hook.
-
-### `onWillUpdateProps`
-
-Just like `onWillStart`, `onWillUpdateProps` is an asynchronous hook. It is
-designed to be run whenever the component props are updated. This could be
-useful to perform some asynchronous task such as fetching updated data.
-
-```js
-function useLoader() {
-  const component = Component.current;
-  const record = useState({});
-
-  async function updateRecord(id) {
-    Object.assign(record, await fetchSomeRecord(id));
-  }
-
-  onWillStart(() => updateRecord(component.props.id));
-  onWillUpdateProps(nextProps => updateRecord(nextProps.id));
-
-  return record;
-}
-```
-
-Note that if there are more than one `onWillUpdateProps` registered callback,
-then they will all be run in parallel.
-
-### `useContext`
-
-See [`useContext`](context.md#usecontext) for reference documentation.
-
-### `useRef`
-
-The `useRef` hook is useful when we need a way to interact with some inside part
-of a component, rendered by Owl. It can work either on a DOM node, or on a component,
-tagged by the `t-ref` directive:
-
-```xml
-<div>
-    <div t-ref="someDiv"/>
-    <SubComponent t-ref="someComponent"/>
-</div>
-```
-
-In this example, the component will be able to access the `div` and the component
-`SubComponent` using the `useRef` hook:
-
-```js
-class Parent extends Component {
-  subRef = useRef("someComponent");
-  divRef = useRef("someDiv");
-
-  someMethod() {
-    // here, if component is mounted, refs are active:
-    // - this.divRef.el is the div HTMLElement
-    // - this.subRef.comp is the instance of the sub component
-    // - this.subRef.el is the root HTML node of the sub component (i.e. this.subRef.comp.el)
-  }
-}
-```
-
-As shown by the example above, html elements are accessed by using the `el`
-key, and components references are accessed with `comp`.
-
-Notes:
-
- if used on a component, the reference will be set in the `refs`
-  variable between `willPatch` and `patched`,
- on a component, accessing `ref.el` will get the root node of the component.
-
-The `t-ref` directive also accepts dynamic values with string interpolation
-(like the [`t-attf-`](qweb_templating_language.md#dynamic-attributes) and
-`t-component` directives). For example,
-
-```xml
-<div t-ref="component_{{someCondition ? '1' : '2'}}"/>
-```
-
-Here, the references need to be set like this:
-
-```js
-this.ref1 = useRef("component_1");
-this.ref2 = useRef("component_2");
-```
-
-References are only guaranteed to be active while the parent component is mounted.
-If this is not the case, accessing `el` or `comp` on it will return `null`.
-
-### `useSubEnv`
-
-The environment is sometimes useful to share some common information between
-all components. But sometimes, we want to _scope_ that knowledge to a subtree.
-
-For example, if we have a form view component, maybe we would like to make some
-`model` object available to all sub components, but not to the whole application.
-This is where the `useSubEnv` hook may be useful: it lets a component add some
-information to the environment in a way that only the component and its children
-can access it:
-
-```js
-class FormComponent extends Component {
-  constructor(...args) {
-    super(...args);
-    const model = makeModel();
-    useSubEnv({ model });
-  }
-}
-```
-
-The `useSubEnv` takes one argument: an object which contains some key/value that
-will be added to the parent environment. Note that it will extend, not replace
-the parent environment. And of course, the parent environment will not be
-affected.
-
-### `useStore`
-
-The `useStore` hook is the entry point for a component to connect to the store.
-See the [store documentation](store.md) for more information.
-
-### `useDispatch`
-
-The `useDispatch` hook is the way for components to get a reference to the store
-`dispatch` function. See the [store documentation](store.md) for more information.
-
-### `useGetters`
-
-The `useGetters` hook is the way for components to get a reference to the store
-getters. See the [store documentation](store.md) for more information.
-
-### Making customized hooks
-
-Hooks are a wonderful way to organize the code of a complex component by feature
-instead of by lifecycle methods. They are like mixins, except that they can be
-easily composed together.
-
-But, like every good things in life, hooks should be used with moderation. They are
-not the solution to every problem.
-
- they may be overkill: if your component needs to perform some action specific
-  to itself (so, the specific code does not need to be shared), there is nothing
-  wrong with a simple class method:
-
-  ```js
-  // maybe overkill
-  class A extends Component {
-    constructor(...args) {
-      super(...args);
-      useMySpecificHook();
-    }
-  }
-
-  // ok
-  class B extends Component {
-    constructor(...args) {
-      super(...args);
-      this.performSpecificTask();
-    }
-  }
-  ```
-
-  Note that the second solution is easier to extend in sub components.
-
- they may be harder to test: if a customized hook injects some external side
-  effect dependency, then it is harder to test without doing some non obvious
-  manipulation. For example, assume that we want to give a reference to a
-  router in a `useRouter` hook. We could do this:
-
-  ```js
-  const router = new Router(...);
-
-  function useRouter() {
-      return router;
-  }
-  ```
-
-  As you can see, this does not _hook_ into the internal of the component. It
-  simply returns a global object, which is difficult to mock.
-
-  A better way would be to do something like this: get the reference from the
-  environment.
-
-  ```js
-  function useRouter() {
-    return Component.current.env.router;
-  }
-  ```
-
-  This means that we give control to the application developer to create the
-  router, which is good, so they can set it up, subclass it, ... And then, to
-  test our components, we can just add a mock router in the environment.
-
-Note: the code above makes use of the `Component.current` property. This is the
-way hooks are able to get a reference to the component currently being created.
@@ -1,134 +0,0 @@
-# 🦉 Miscellaneous 🦉
-
-## Content
-
- [Portal](#portal)
- [AsyncRoot](#asyncroot)
-
-## `Portal`
-
-### Overview
-
-The component `Portal` is meant to be used as a transparent way to 'teleport' a piece
-of DOM to the node represented by its sole `target` props.
-
-This component aims at helping the implementation of the needed infrastructure
-for modals (as in `bootstrap-modal`).
-
-### Usage
-
-The content it will teleport is defined within the `<Portal>` node and
-internally uses the `default` [Slot](component.md#slots).
-
-This slot must contain only **one** node, which in turn can have as many children as necessary.
-
-The element under which the content will be teleported is represented as a selector
-by the `target` props which only accepts a string as value.
-
-The `target` props only supports static selector, and is not meant to be passed to `Portal`
-as a variable. Namely, `<Portal target="'body'" />` is the intended use.
-By contrast, `<Portal target="state.target" />` is not supported.
-
-The component `Portal` has no particular state, rather it is meant to be a slave to its parent,
-and ultimately just a way for the parent to teleport a piece of its own DOM elsewhere.
-
-The `Portal`'s root node is always `<portal/>` and is placed where the teleported content
-_would have_ been. It is this element that the [teleported events](#expected-behaviors) are re-directed on.
-
-### Example
-
-The canonic use-case is to implement a Dialog, where a Component may choose to break the natural
-workflow to help the user put in some data, which it could use later on.
-
-JavaScript:
-
-```js
-const { Component } = owl;
-const { Portal } = owl.misc;
-
-class TeleportedComponent extends Component {}
-class App extends Component {
-  static components = { Portal, TeleportedComponent };
-}
-
-const app = new App();
-app.mount(document.body);
-```
-
-XML:
-
-```xml
-<templates>
-    <div t-name="TeleportedComponent">
-        <span>I will move soon enough</span>
-    </div>
-
-    <div t-name="App">
-        <span>I am like the rest of us</span>
-        <Portal target="'body'">
-            <TeleportedComponent />
-        </Portal>
-    </div>
-</templates>
-```
-
-In this example, the `Portal` component will teleport the `TeleportedComponent`'s `div` as a child of the `body`.
-`TeleportedComponent` is acting as a Dialog here.
-
-The resulting DOM will look like:
-
-```xml
-<body>
-    <div>
-        <span>I am like the rest of us</span>
-        <portal></portal>
-    </div>
-    <div>
-        <span>I will move soon enough</span>
-    </div>
-</body>
-```
-
-### Expected Behaviors
-
-The teleported piece is updated as any other `Component`'s DOM and in the same sequence.
-Namely the teleported piece will be updated in function of its parents components, and patched as
-a normal child.
-
-The [_business_ events](component.md#event-handling) triggered by a child component will be stopped
-to not bubble outside of the `target`. They will, on the other hand, be re-directed onto the
-`Portal`'s root node and bubble up the DOM as if it were triggered by a regular child component.
-
-Beware that those re-directed events are copies of the original event.
-They have:
-
- The same payload.
- The same `originalComponent` than their original counterpart,
-  that is the actual Component that triggered it.
- A **different** `target` property than their original counterpart.
-  The `target` of a re-directed event is necessarily the `Portal`'s root node.
-
-Pure DOM events do not follow this pattern and are free to bubble their natural, unaltered way
-up to the `body`.
-
-## `AsyncRoot`
-
-When this component is used, a new rendering sub tree is created, such that the
-rendering of that component (and its children) is not tied to the rendering of
-the rest of the interface. It can be used on an asynchronous component, to
-prevent it from delaying the rendering of the whole interface, or on a
-synchronous one, such that its rendering isn't delayed by other (asynchronous)
-components. Note that this directive has no effect on the first rendering, but
-only on subsequent ones (triggered by state or props changes).
-
-```xml
-<div t-name="ParentComponent">
-  <SyncChild />
-  <AsyncRoot>
-     <AsyncChild/>
-  </AsyncRoot>
-</div>
-```
-
-The `AsyncRoot` assumes that there is exactly one root node inside it. It can
-be a dom node or a component.
@@ -1,52 +0,0 @@
-# 🦉 Observer 🦉
-
-Owl needs to be able to react to state changes. For example, whenever the state
-of a component is changed, Owl needs to rerender it. To help with that, there is
-an Observer class. Its job is to observe the state of an object (or array), and
-to react to any change. The observer is implemented with the native `Proxy`
-object. Note that this means that it will not work on older browsers.
-
-Note that the `Observer` is used by the `useState` and `useContext` hooks. This
-is the way most Owl applications will create observers. For the majority of
-use cases, there is no need to directly instantiate an observer.
-
-## Example
-
-For example, this code will display `update` in the console:
-
-```javascript
-const observer = new owl.Observer();
-observer.notifyCB = () => console.log("update");
-const obj = observer.observe({ a: { b: 1 } });
-
-obj.a.b = 2;
-```
-
-This example shows that an observer can observe nested properties.
-
-## Reference
-
-**observe** An observer can observe multiple values with the `observe` method.
-This method takes an object or an array as its argument and will return a proxy
-(which is mapped to the initial object/array). With this proxy, the observer
-can detect whenever any internal value is changed.
-
-**Registering a callback** Whenever an observer sees a state change, it will
-call its `notifyCB` method. No additional information is given to the callback.
-
-**deepRevNumber** Each observed value has an internal revision number, which
-is incremented every time the value is observed. Sometimes, it can be useful
-to obtain that number:
-
-```js
-const observer = new owl.Observer();
-const obj = observer.observe({ a: { b: 1 } });
-
-observer.deepRevNumber(obj.a); // 1
-obj.a.b = 2;
-
-observer.deepRevNumber(obj.a); // 2
-```
-
-The `deepRevNumber` can also return 0, which indicates that the value is not
-observed.
@@ -1,97 +0,0 @@
-# 🦉 Props 🦉
-
-## Content
-
- [Overview](#overview)
- [Definition](#definition)
- [Good Practices](#good-practices)
- [Dynamic Props](#dynamic-props)
-
-## Overview
-
-In Owl, `props` (short for _properties_) is an object which contains every piece
-of data given to a component by its parent.
-
-```js
-class Child extends Component {
-  static template = xml`<div><t t-esc="props.a"/><t t-esc="props.b"/></div>`;
-}
-
-class Parent extends Component {
-  static template = xml`<div><ComponentA a="state.a" b="'string'"/></div>`;
-  static components = { Child };
-  state = useState({ a: "fromparent" });
-}
-```
-
-In this example, the `Child` component receives two props from its parent: `a`
-and `b`. They are collected into a `props` object by Owl, with each value being
-evaluated in the context of the parent. So, `props.a` is equal to `'fromparent'` and
-`props.b` is equal to `'string'`.
-
-Note that `props` is an object that only makes sense from the perspective of the
-child component.
-
-## Definition
-
-The `props` object is made of every attributes defined on the template, with the
-following exceptions:
-
- every attribute starting with `t-` are not props (they are QWeb directives),
- `style` and `class` attributes are excluded as well (they are applied by Owl on
-  the root element of the component).
-
-In the following example:
-
-```xml
-<div>
-    <ComponentA a="state.a" b="'string'"/>
-    <ComponentB t-if="state.flag" model="model"/>
-    <ComponentC style="color:red;" class="left-pane" />
-</div>
-```
-
-the `props` object contains the following keys:
-
- for `ComponentA`: `a` and `b`,
- for `ComponentB`: `model`,
- for `ComponentC`: empty object
-
-## Good Practices
-
-A `props` object is a collection of values that come from the parent. As such,
-they are owned by the parent, and should never be modified by the child:
-
-```js
-class MyComponent extends Component {
-  constructor(parent, props) {
-    super(parent, props);
-    props.a.b = 43; // Never do that!!!
-  }
-}
-```
-
-Props should be considered readonly, from the perspective of the child component.
-If there is a need to modify them, then the request to update them should be
-sent to the parent (for example, with an event).
-
-Any value can go in a props. Strings, objects, classes, or even callbacks could
-be given to a child component (but then, in the case of callbacks, communicating
-with events seems more appropriate).
-
-## Dynamic Props
-
-The `t-props` directive can be used to specify totally dynamic props:
-
-```xml
-<div t-name="ParentComponent">
-    <Child t-props="some.obj"/>
-</div>
-```
-
-```js
-class ParentComponent {
-  static components = { Child };
-  some = { obj: { a: 1, b: 2 } };
-}
-```
@@ -1,103 +0,0 @@
-# 🦉 Props Validation 🦉
-
-As an application becomes complex, it may be quite unsafe to define props in an informal way. This leads to two issues:
-
- hard to tell how a component should be used, by looking at its code.
- unsafe, it is easy to send wrong props into a component, either by refactoring a component, or one of its parents.
-
-A props type system solves both issues, by describing the types and shapes
-of the props. Here is how it works in Owl:
-
- `props` key is a static key (so, different from `this.props` in a component instance)
- it is optional: it is ok for a component to not define a `props` key.
- props are validated whenever a component is created/updated
- props are only validated in `dev` mode (see [config page](config.md#mode))
- if a key does not match the description, an error is thrown
- it validates keys defined in (static) `props`. Additional keys given by the
-  parent will cause an error.
-
-For example:
-
-```js
-class ComponentA extends owl.Component {
-    static props = ['id', 'url'];
-
-    ...
-}
-
-class ComponentB extends owl.Component {
-  static props = {
-    count: {type: Number},
-    messages: {
-      type: Array,
-      element: {type: Object, shape: {id: Boolean, text: 'string' }
-    },
-   date: Date,
-   combinedVal: [Number, Boolean]
-  };
-
-  ...
-}
-```
-
- it is an object or a list of strings
- a list of strings is a simplified props definition, which only lists the name
-  of the props. Also, if the name ends with `?`, it is considered optional.
- all props are by default required, unless they are defined with `optional: true`
-  (in that case, validation is only done if there is a value)
- valid types are: `Number, String, Boolean, Object, Array, Date, Function`, and all
-  constructor functions (so, if you have a `Person` class, it can be used as a type)
- arrays are homogeneous (all elements have the same type/shape)
-
-For each key, a `prop` definition is either a boolean, a constructor, a list of constructors, or an object:
-
- a boolean: indicate that the props exists, and is mandatory.
- a constructor: this should describe the type, for example: `id: Number` describe
-  the props `id` as a number
- a list of constructors. In that case, this means that we allow more than one
-  type. For example, `id: [Number, String]` means that `id` can be either a string
-  or a number.
- an object. This makes it possible to have more expressive definition. The following sub keys are then allowed (but not mandatory):
-  - `type`: the main type of the prop being validated
-  - `element`: if the type was `Array`, then the `element` key describes the type of each element in the array. If it is not set, then we only validate the array, not its elements,
-  - `shape`: if the type was `Object`, then the `shape` key describes the interface of the object. If it is not set, then we only validate the object, not its elements,
-  - `validate`: this is a function which should return a boolean to determine if
-    the value is valid or not. Useful for custom validation logic.
-
-Examples:
-
-```js
-  // only the existence of those 3 keys is documented
-  static props = ['message', 'id', 'date'];
-```
-
-```js
-  // size is optional
-  static props = ['message', 'size?'];
-```
-
-```js
-  static props = {
-    messageIds: {type: Array, element: Number},  // list of number
-    otherArr: {type: Array},   // just array. no validation is made on sub elements
-    otherArr2: Array,   // same as otherArr
-    someObj: {type: Object},  // just an object, no internal validation
-    someObj2: {
-      type: Object,
-      shape: {
-        id: Number,
-        name: {type: String, optional: true},
-        url: String
-      ]},    // object, with keys id (number), name (string, optional) and url (string)
-    someFlag: Boolean,     // a boolean, mandatory (even if `false`)
-    someVal: [Boolean, Date],   // either a boolean or a date
-    otherValue: true,     // indicates that it is a prop
-    kindofsmallnumber: {
-      type: Number,
-      validate: n => (0 <= n && n <= 10)
-    },
-    size: {
-      validate:  e => ["small", "medium", "large"].includes(e)
-    },
-  };
-```
@@ -1,151 +0,0 @@
-# 🦉 QWeb Engine 🦉
-
-## Content
-
- [Overview](#overview)
- [Reference](#reference)
-
-## Overview
-
-[QWeb](https://www.odoo.com/documentation/13.0/reference/qweb.html) is the primary
-templating engine used by Odoo. The QWeb class in the OWL project is an
-implementation of that specification with a few interesting points:
-
- it compiles templates into functions that output a virtual DOM instead of a
-  string. This is necessary for the component system.
- it has a few extra directives: `t-component`, `t-on`, ...
-
-We present in this section the engine, not the templating language.
-
-## Reference
-
-This section is about the javascript code that implements the `QWeb` specification.
-Owl exports a `QWeb` class in `owl.QWeb`. To use it, it just needs to be
-instantiated:
-
-```js
-const qweb = new owl.QWeb();
-```
-
-Its API is quite simple:
-
- **`constructor(config)`**: constructor. Takes an optional configuration object
-  with an optional `templates` string to add initial
-  templates (see `addTemplates` for more information on format of the string)
-  and an optional `translateFn` translate function (see the section on
-  [translations](#translations)).
-
-  ```js
-  const qweb = new owl.QWeb({ templates: TEMPLATES, translateFn: _t });
-  ```
-
- **`addTemplate(name, xmlStr, allowDuplicate)`**: add a specific template.
-
-  ```js
-  qweb.addTemplate("mytemplate", "<div>hello</div>");
-  ```
-
-  If the optional `allowDuplicate` is set to `true`, then `QWeb` will simply
-  ignore templates added for a second time. Otherwise, `QWeb` will crash.
-
- **`addTemplates(xmlStr)`**: add a list of templates (identified by `t-name`
-  attribute).
-
-  ```js
-  const TEMPLATES = `
-    <templates>
-      <div t-name="App" class="main">main</div>
-      <div t-name="OtherComponent">other component</div>
-    </templates>`;
-  qweb.addTemplates(TEMPLATES);
-  ```
-
- **`render(name, context, extra)`**: renders a template. This returns a `vnode`,
-  which is a virtual representation of the DOM (see [vdom doc](../architecture/vdom.md)).
-
-  ```js
-  const vnode = qweb.render("App", component);
-  ```
-
- **`renderToString(name, context)`**: renders a template, but returns an html
-  string.
-
-  ```js
-  const str = qweb.renderToString("someTemplate", somecontext);
-  ```
-
- **`registerTemplate(name, template)`**: static function to register a global
-  QWeb template. This is useful for commonly used components accross the
-  application, and for making a template available to an application without
-  having a reference to the actual QWeb instance.
-
-  ```js
-  QWeb.registerTemplate("mytemplate", `<div>some template</div>`);
-  ```
-
- **`registerComponent(name, Component)`**: static function to register an OWL Component
-  to QWeb's global registry. Globally registered Components can be used in
-  templates (see the `t-component` directive). This is useful for commonly used
-  components accross the application.
-
-  ```js
-  class Dialog extends owl.Component { ... }
-  QWeb.registerComponent("Dialog", Dialog);
-
-  ...
-
-  class ParentComponent extends owl.Component { ... }
-  qweb.addTemplate("ParentComponent", "<div><Dialog/></div>");
-  ```
-
-In some way, a `QWeb` instance is the core of an Owl application. It is the only
-mandatory element of an [environment](environment.md). As such, it
-has an extra responsibility: it can act as an event bus for internal communication
-between Owl classes. This is the reason why `QWeb` actually extends [EventBus](event_bus.md).
-
-### Translations
-
-If properly setup, Owl QWeb engine can translate all rendered templates. To do
-so, it needs a translate function, which takes a string and returns a string.
-
-For example:
-
-```js
-const translations = {
-  hello: "bonjour",
-  yes: "oui",
-  no: "non"
-};
-const translateFn = str => translations[str] || str;
-
-const qweb = new QWeb({ translateFn });
-```
-
-Once setup, all rendered templates will be translated using `translateFn`:
-
- each text node will be replaced with its translation,
- each of the following attribute values will be translated as well: `title`,
-  `placeholder`, `label` and `alt`,
- translating text nodes can be disabled with the special attribute `t-translation`,
-  if its value is `off`.
-
-So, with the above `translateFn`, the following templates:
-
-```xml
-<div>hello</div>
-<div t-translation="off">hello</div>
-<div>Are you sure?</div>
-<input placeholder="hello" other="yes"/>
-```
-
-will be rendered as:
-
-```xml
-<div>bonjour</div>
-<div>hello</div>
-<div>Are you sure?</div>
-<input placeholder="bonjour" other="yes"/>
-```
-
-Note that the translation is done during the compilation of the template, not
-when it is rendered.
@@ -1,148 +0,0 @@
-# 🦉 Utils 🦉
-
-Owl export a few useful utility functions, to help with common issues. Those
-functions are all available in the `owl.utils` namespace.
-
-## Content
-
- [`whenReady`](#whenready): executing code when DOM is ready
- [`loadJS`](#loadjs): loading script files
- [`loadFile`](#loadfile): loading a file (useful for templates)
- [`escape`](#escape): sanitizing strings
- [`debounce`](#debounce): limiting rate of function calls
- [`shallowEqual`](#shallowequal): shallow object comparison
-
-## `whenReady`
-
-The function `whenReady` returns a `Promise` resolved when the DOM is ready (if
-not ready yet, resolved directly otherwise). If called with a callback as
-argument, it executes it as soon as the DOM ready (or directly).
-
-```js
-Promise.all([loadFile("templates.xml"), owl.utils.whenReady()]).then(function([templates]) {
-  const qweb = new owl.QWeb({ templates });
-  const app = new App({ qweb });
-  app.mount(document.body);
-});
-```
-
-or alternatively:
-
-```js
-owl.utils.whenReady(function() {
-  const qweb = new owl.QWeb();
-  const app = new App({ qweb });
-  app.mount(document.body);
-});
-```
-
-## `loadJS`
-
-`loadJS` takes a url (string) for a javascript resource, and loads it (by adding
-a script tag in the document head). It returns a promise, so the caller can
-properly reacts when it is ready. Also, it is smart: it maintains a list of urls
-previously loaded (or currently being loaded), and prevent doing twice the work.
-
-For example, it is useful for lazy loading external libraries:
-
-```js
-class MyComponent extends owl.Component {
-  willStart() {
-    return owl.utils.loadJS("/static/libs/someLib.js");
-  }
-}
-```
-
-## `loadFile`
-
-`loadFile` is a helper function to fetch a file. It simply
-performs a `GET` request and returns the resulting string in a promise. The
-initial usecase for this function is to load a template file. For example:
-
-```js
-async function makeEnv() {
-  const templates = await owl.utils.loadFile("templates.xml");
-  const qweb = new owl.QWeb({ templates });
-  return { qweb };
-}
-```
-
-Note that unlike `loadJS`, this function returns the content of the file as a
-string. It does not add a `script` tag or any other side effect.
-
-## `escape`
-
-Sometimes, we need to display dynamic data (for example user-generated data) in
-the user interface. If this is done by a `QWeb` template, it is not an issue:
-
-```xml
-    <div><t t-esc="user.data"/></div>
-```
-
-The `QWeb` engine will create a `div` node and add the content of the `user.data`
-string as a text node, so the web browser will not parse it as html. However,
-it may be a problem if this is done with some javascript code like this:
-
-```js
-class BadComponent extends Component {
-  // some template with a ref to a div
-  // some code ...
-
-  mounted() {
-    this.divRef.el.innerHTML = this.state.value;
-  }
-}
-```
-
-In this case, the content of the `div` will be parsed as html, which may inject
-unwanted behaviour. To fix this, the `escape` function will simply transform a
-string into an escaped version of the same string, which will be properly displayed
-by the browser, but which will not be parsed as html (for example, `"<ok>"` is
-escaped to the string: `"&lt;ok&gt;"`). So, the bad example above can be fixed
-with the following change:
-
-```js
-this.divRef.el.innerHTML = owl.utils.escape(this.state.value);
-```
-
-## `debounce`
-
-The `debounce` function is useful when we want to limit the number of times some
-function/action is perfomed. For example, this may be useful to prevent issue
-with people double clicking on a button.
-
-It takes three arguments:
-
- `func` (function): this is the function that will be rate limited
- `wait` (number): this is the number of milliseconds that we want to use to
-  rate limit the function `func`
- `immediate` (optional, boolean, default=false): if `immediate` is true, the
-  function will be triggered immediately (leading edge of the interval). If false,
-  the function will be triggered at the end (trailing edge).
-
-It returns a function. For example:
-
-```js
-const debounce = owl.utils.debounce;
-window.addEventListener("mousemove", debounce(doSomething, 100));
-```
-
-As this example shows, it is usualy useful for event handlers which are triggered
-very quickly, such as `scroll` or `mousemove` events.
-
-## `shallowEqual`
-
-This function checks if two objects have the same values assigned to each keys:
-
-```js
-shallowEqual({ a: 1, b: 2 }, { a: 1, b: 2 }); // true
-shallowEqual({ a: 1, b: 2 }, { a: 1, b: 3 }); // false
-```
-
-However, for performance reasons, it assumes that the two objects have the same
-keys. If we are in a situation where this is not guaranteed, the following code
-will work:
-
-```js
-const completeShallowEqual = (a, b) => shallowEqual(a, b) && shallowEqual(b, a);
-```
@@ -67,9 +67,6 @@ function makeEnvironment() {
    await env.router.start();
    return env;
 }
-
-App.env = makeEnvironment();
-// create root component here
 ```

 Notice that the router needs to be started. This is an asynchronous operation
@@ -100,13 +97,6 @@ The `Router` constructor takes three arguments:
 - an optional object (with the only key `mode` which can be `history` (default
  value) or `hash`).

-`history` will use the browser [History API](https://developer.mozilla.org/en-US/docs/Web/API/History_API) as the mechanism to manage URL.\
-Example: `https://yourdomain.tld/my_custom_route`.\
-For this mechanism to work, you need a way to configure your web server accordingly.
-
-`hash` will manipulate the hash of the URL.\
-Example: `https://yourdomain.tld/index.html#/my_custom_route`.
-
 ```js
 const ROUTES = [...];
 const router = new owl.router.Router(env, ROUTES, {mode: 'history'});
@@ -9,9 +9,6 @@
  - [Actions](#actions)
  - [Getters](#getters)
  - [Connecting a Component](#connecting-a-component)
-  - [`useStore`](#usestore)
-  - [`useDispatch`](#usedispatch)
-  - [`useGetters`](#usegetters)
  - [Semantics](#semantics)
  - [Good Practices](#good-practices)

@@ -19,14 +16,13 @@

 Managing the state in an application is not an easy task. In some cases, the
 state of an application can be part of the component tree, in a natural way.
-However, there are situations where some parts of the state need to be displayed
+However, there are situations where some part of the state need to be displayed
 in various parts of the user interface, and then, it is not obvious which
 component should own which part of the state.

 Owl's solution to this issue is a centralized store. It is a class that owns
-some (or all) state, and lets the developer update it in a structured way, with
-`actions`. Owl components can then connect to the store to read their relevant
-state, and they will be rerendered if the state is updated.
+some state, and let the developer update it in a structured way, with `actions`.
+Owl components can then connect to the store, and will be updated if necessary.

 Note: Owl store is inspired by React Redux and VueX.

@@ -51,7 +47,7 @@ const state = {
 };

 const store = new owl.Store({ state, actions });
-store.on("update", null, () => console.log(store.state));
+store.on("update", () => console.log(store.state));

 // updating the state
 store.dispatch("addTodo", "fix all bugs");
@@ -114,15 +110,6 @@ const actions = {
 };
 ```

-The first argument to an action method is an object with four keys:
-
- `state`: the current state of the store content,
- `dispatch`: a function that can be used to dispatch other actions,
- `getters`: an object containing all getters defined in the store,
- `env`: the current environment. This is useful sometimes, in particular if
-  an action needs to apply some side effects (such as performing an rpc), and
-  the `rpc` method is located in the environment.
-
 Actions are called with the `dispatch` method on the store, and can receive an
 arbitrary number of arguments.

@@ -135,7 +122,7 @@ call.

 Also, it is important to be aware that we need to be careful with asynchronous
 logic. Each state change will potentially trigger a rerendering, so we need to
-make sure that we do not have a partially corrupted state. Here is an example that
+make sure that we do not have a partial corrupted state. Here is an example that
 is likely not a good idea:

 ```javascript
@@ -188,7 +175,7 @@ transform the data contained in the store.
 const getters = {
  getPost({ state }, id) {
    const post = state.posts.find(p => p.id === id);
-    const author = state.authors.find(a => a.id === post.id);
+    const author = state.authors.find(a => (a.id = post.id));
    return {
      id,
      author,
@@ -203,135 +190,100 @@ const post = store.getters.getPost(id);

 Getters take _at most_ one argument.

-Note that getters are not cached.
+Note that getters are cached if they don't take any argument, or their argument
+is a string or a number.

 ### Connecting a Component

-At some point, we need a way to interact with the store from a component. This
-can be done with the help of the three store hooks:
-
- [`useStore`](#usestore) to subscribe a component to some part of the store state,
- [`useDispatch`](#usedispatch) to get a reference to a dispatch function,
- [`useGetters`](#usegetters) to get a reference to the getters defined in the store.
-
-Assume we have this store:
+At some point, we need a way to access the state in the store from a component.
+By default, an Owl `Component` is not connected to any store. To do that, we
+need to create a component inheriting from `OwlComponent`:

 ```javascript
 const actions = {
  increment({ state }, val) {
-    state.counter.value += val;
+    state.counter += val;
  }
 };

 const state = {
-  counter: { value: 0 }
+  counter: 0
 };
 const store = new owl.Store({ state, actions });
-```

-A counter component can then select this value and dispatch an action like this:
-
-```js
-class Counter extends Component {
-  counter = useStore(state => state.counter);
-  dispatch = useDispatch();
+class Counter extends owl.ConnectedComponent {
+  static mapStoreToProps(state) {
+    return {
+      value: state.counter
+    };
+  }
+  increment() {
+    this.env.store.dispatch("increment");
+  }
 }

 const counter = new Counter({ store, qweb });
 ```

 ```xml
-<button t-name="Counter" t-on-click="dispatch('increment')">
-  Click Me! [<t t-esc="counter.value"/>]
+<button t-name="Counter" t-on-click="increment">
+  Click Me! [<t t-esc="props.value"/>]
 </button>
 ```

-### `useStore`
+The `ConnectedComponent` class can be configured with the following fields:

-The `useStore` hook is used to select some part of the store state. It accepts
-two arguments:
+- `mapStoreToProps`: a function that extracts the `props` of the Component
+  from the `state` of the `Store` and returns them as a dict.
+- `getStore`: a function that takes the `env` in arguments and returns an
+  instance of `Store` to connect to (if not given, connects to `env.store`)
+- `hashFunction`: the function to use to detect changes in the state (if not
+  given, generates a function that uses revision numbers, incremented at
+  each state change)
+- `deep` (boolean): [only useful if no hashFunction is given] if `false`, only watch
+  for top level state changes (`true` by default)

- a selector function, which takes the store state as first argument (and the
-  component props as second argument) and which must return the part of the
-  store state that will be made available and observed for changes,
- optionally, an object which can have the following optional keys:
-  - a `store` key containing a store object if we want to use another store than
-    the default store,
-  - an `isEqual` key containing an equality function if we want to specialize
-    the comparison (the function must accept two arguments: the previous result
-    and the new result, and must return whether they are equal),
-  - and an `onUpdate` key containing an update function if we want to execute an
-    arbitrary code every time the selected state changes (the function will
-    receive one argument, the new result, and can execute arbitrary code).
+Note that the class `ConnectedComponent` has a `dispatch` method. This means
+that the previous example could be simplified like this:

-If the `useStore` selector returns a sub part of the store state, the component
-will only be rerendered whenever this part of the state changes. Otherwise, it
-will perform a strict equality check (unless the `isEqual` option is defined,
-then it will call it) and will update the component every time this check fails.
-
-Note that if the selector function returns a primitive type, the result of
-`useStore` will be immutable and it will not react to changes. In this case, it
-is important to define the `onUpdate` option to properly update the value
-manually when it changes.
-
-Also, the return value from `useStore` is not supposed to be modified. The store
-state should only be updated with actions.
-
-### `useDispatch`
-
-The `useDispatch` hook is useful when a component needs to be able to dispatch
-actions. It takes an optional argument, which is a store. If not given, it will
-use the store in the environment.
-
-Note that a component does not need to be connected in any other way to the store.
-For example:
-
-```js
-class DoSomethingButton extends Component {
-  static template = xml`<button t-on-click="dispatch('something')">Click</button>`;
-  dispatch = useDispatch();
+```javascript
+class Counter extends owl.ConnectedComponent {
+  static mapStoreToProps(state) {
+    return {
+      value: state.counter
+    };
+  }
 }
 ```

-### `useGetters`
-
-The `useGetters` hook is useful when a component needs to be able to use the
-getters defined in a store. It takes an optional argument, which is a store. If
-not given, it will use the store in the environment.
-
-Note that a component does not need to be connected in any other way to the store.
-For example:
-
-```js
-class InfoButton extends Component {
-  static template = xml`<span><t t-esc="getters.somevalue()"></span>`;
-  getters = useGetters();
-}
+```xml
+<button t-name="Counter" t-on-click="dispatch('increment')">
+  Click Me! [<t t-esc="props.value"/>]
+</button>
 ```

 ### Semantics

-The `Store` class and the `useStore` hook try to be smart and to optimize as much
+The `Store` and the `ConnectedComponent` try to be smart and to optimize as much
 as possible the rendering and update process. What is important to know is:

 - components are always updated in the order of their creation (so, parent
-  before children),
- they are updated only if they are in the DOM,
+  before children)
+- they are updated only if they are in the DOM
 - if a parent is asynchronous, the system will wait for it to complete its
-  update before updating other components,
+  update before updating other components.
 - in general, updates are not coordinated. This is not a problem for synchronous
  components, but if there are many asynchronous components, this could lead to
-  a situation where some part of the UI is updated and some other part of the UI is
+  a situation where some part of the UI is updated and other parts of the UI is
  not updated.

 ### Good Practices

 - avoid asynchronous components as much as possible. Asynchronous components
-  lead to situations where parts of the UI is not updated immediately,
+  lead to situations where parts of the UI is not updated immediately.
 - do not be afraid to connect many components, parent or children if needed. For
-  example, a `MessageList` component could get a list of ids in its `useStore`
-  call and a `Message` component could get the data of its own
-  message,
- since the `useStore` function is called for each connected component,
+  example, a `MessageList` component could get a list of ids in its `mapStoreToProps` and a `Message` component could get the data of its own
+  message
+- since the `mapStoreToProps` function is called for each connected component,
  for each state update, it is important to make sure that these functions are
  as fast as possible.
@@ -1,15 +1,8 @@
 # 🦉 Tags 🦉

-## Content
-
- [Overview](#overview)
- [`xml` tag](#xml-tag)
-
-## Overview
-
-Tags are very small helpers to make it easy to write inline templates. There is
+Tags are very small helper to make it easy to write inline templates. There is
 only one currently available tag: `xml`, but we plan to add other tags later,
-such as a `css` tag, which will be used to write [single file components](../tooling.md#single-file-component).
+such as a `css` tag, which will be used to write single file components.

 ## XML tag

@@ -38,8 +31,8 @@ With tags, this process is slightly simplified. The name is uniquely generated,
 and the template is automatically registered:

 ```js
-const { Component } = owl;
-const { xml } = owl.tags;
+import { Component } from 'owl'
+import { xml } from 'owl/tags'

 class MyComponent extends Component {
    static template = xml`
@@ -3,10 +3,10 @@
 ## Content

 - [Overview](#overview)
+- [Development Mode](#development-mode)
 - [Playground](#playground)
 - [Benchmarks](#benchmarks)
 - [Single File Component](#single-file-component)
- [Debugging Script](#debugging-script)

 ## Overview

@@ -21,6 +21,26 @@ by using a static http server. A simple python
 server is available in `server.py`. There is also a npm script to start it:
 `npm run tools` (and its version with a watcher: `npm run tools:watch`).

+## Development Mode
+
+By default, Owl is in _production_ mode, this means that it will try to do its
+job fast, and skip some expensive operations. However, in some cases, it is
+convenient to have better information on what is going on, this is the purpose
+of the dev mode.
+
+Owl has a mode flag, in `owl.__info__.mode`. Its default value is `prod`, but
+it can be set to `dev`:
+
+```js
+owl.__info__.mode = "dev";
+```
+
+Note that templates compiled with the `prod` settings will not be recompiled.
+So, changing this setting is best done at startup.
+
+An important job done by the `dev` mode is to validate props for each component
+creation and update. Also, extra props will cause an error.
+
 ## Playground

 The playground is an important application designed to help learning and
@@ -40,21 +60,12 @@ useful to compare various performance metrics on some tasks.

 ## Single File Component

-It is very useful to group code by feature instead of by type of file. It makes
-it easier to scale application to larger size.
-
-To do so, Owl currently has a small helper that makes it easy to define a
-template inside a javascript (or typescript) file: the [`xml`](reference/tags.md#xml-tag)
-helper. With this, a template is automatically registered to [QWeb](reference/qweb_engine.md).
-
-This means that the template and the javascript code can be defined in the same
-file. It is not currently possible to add css to the same file, but Owl may
-get a `css` tag helper later.
+If you want to have `xml` syntax highlighting while using the `xml` helper which
+helps you define inline templates, there is a VS Code addon `Comment tagged template`
+which, if installed, does exactly that. To enable it, you need to add a comment,
+like this:

 ```js
-const { Component } = owl;
-const { xml } = owl.tags;
-
 // -----------------------------------------------------------------------------
 // TEMPLATE
 // -----------------------------------------------------------------------------
@@ -74,33 +85,3 @@ class MyComponent extends Component {
  // rest of component...
 }
 ```
-
-Note that the above example has an inline xml comment, just after the `xml` call.
-This is useful for some editor plugins, such as the VS Code addon
-`Comment tagged template`, which, if installed, add syntax highlighting to the
-content of the template string.
-
-## Debugging Script
-
-## Debugging
-
-Non trivial applications become quickly more difficult to understand. It is then
-useful to have a solid understanding of what is going on. To help with that,
-logging useful information is extremely valuable. There is a [javascript file](../tools/debug.js) which can be evaluated in an application.
-
-Once it is executed, it will log a lot of information on each component main hooks. The following code is a minified version to make it easier to copy/paste:
-
-```
-function debugOwl(t,n){let e,o="[OWL_DEBUG]";function s(t){let n=JSON.stringify(t||{});return n.length>200&&(n=n.slice(0,200)+"..."),n}if(Object.defineProperty(t.Component,"current",{get:()=>e,set(i){e=i;const r=i.constructor.name;if(n.componentBlackList&&n.componentBlackList.test(r))return;if(n.componentWhiteList&&!n.componentWhiteList.test(r))return;let l;Object.defineProperty(e,"__owl__",{get:()=>l,set(e){!function(e,i,r){let l=`${i}<id=${r}>`,c=t=>console.log(`${o} ${l} ${t}`),u=t=>(!n.methodBlackList||!n.methodBlackList.includes(t))&&!(n.methodWhiteList&&!n.methodWhiteList.includes(t));u("constructor")&&c(`constructor, props=${s(e.props)}`);u("willStart")&&t.hooks.onWillStart(()=>{c("willStart")});u("mounted")&&t.hooks.onMounted(()=>{c("mounted")});u("willUpdateProps")&&t.hooks.onWillUpdateProps(t=>{c(`willUpdateProps, nextprops=${s(t)}`)});u("willPatch")&&t.hooks.onWillPatch(()=>{c("willPatch")});u("patched")&&t.hooks.onPatched(()=>{c("patched")});u("willUnmount")&&t.hooks.onWillUnmount(()=>{c("willUnmount")});const d=e.__render.bind(e);e.__render=function(...t){c("rendering template"),d(...t)};const h=e.render.bind(e);e.render=function(...t){const n=e.__owl__;let o="render";return n.isMounted||n.currentFiber||(o+=" (warning: component is not mounted, this render has no effect)"),c(o),h(...t)};const p=e.mount.bind(e);e.mount=function(...t){return c("mount"),p(...t)}}(i,r,(l=e).id)}})}}),n.logScheduler){let n=t.Component.scheduler.start,e=t.Component.scheduler.stop;t.Component.scheduler.start=function(){this.isRunning||console.log(`${o} scheduler: start running tasks queue`),n.call(this)},t.Component.scheduler.stop=function(){this.isRunning&&console.log(`${o} scheduler: stop running tasks queue`),e.call(this)}}if(n.logStore){let n=t.Store.prototype.dispatch;t.Store.prototype.dispatch=function(t,...e){return console.log(`${o} store: action '${t}' dispatched. Payload: '${s(e)}'`),n.call(this,t,...e)}}}
-debugOwl(owl, {
-  // componentBlackList: /App/,  // regexp
-  // componentWhiteList: /SomeComponent/, // regexp
-  // methodBlackList: ["mounted"], // list of method names
-  // methodWhiteList: ["willStart"], // list of method names
-  logScheduler: false,  // display/mute scheduler logs
-  logStore: true,     // display/mute store logs
-});
-```
-
-Note that it is certainly useful to run this code at some point in an application,
-just to get a feel of what each user action implies, for the framework.
@@ -0,0 +1,63 @@
+# 🦉 Utils 🦉
+
+Owl export a few useful utility functions, to help with common issues. Those
+functions are all available in the `owl.utils` namespace.
+
+## Content
+
+- [`whenReady`](#whenready): executing code when DOM is ready
+- [`loadJS`](#loadjs): loading script files
+- [`loadTemplates`](#loadtemplates): loading xml files
+- [`escape`](#escape): sanitizing strings
+- [`debounce`](#debounce): limiting rate of function calls
+
+## `whenReady`
+
+The function `whenReady` returns a `Promise` resolved when the DOM is ready (if
+not ready yet, resolved directly otherwise). If called with a callback as
+argument, it executes it as soon as the DOM ready (or directly).
+
+```js
+Promise.all([loadTemplates(), owl.utils.whenReady()]).then(function([templates]) {
+  const qweb = new owl.QWeb(templates);
+  const app = new App({ qweb });
+  app.mount(document.body);
+});
+```
+
+```js
+owl.utils.whenReady(function() {
+  const qweb = new owl.QWeb();
+  const app = new App({ qweb });
+  app.mount(document.body);
+});
+```
+
+## `loadJS`
+
+`loadJS` takes a url (string) for a javascript resource, and loads it. It returns
+a promise, so the caller can properly react when it is ready. Also, it is smart:
+it maintains a list of urls previously loaded (or currently being loaded), and
+prevent doing twice the work.
+
+```js
+class MyComponent extends owl.Component {
+  willStart() {
+    return owl.utils.loadJS("/static/libs/someLib.js");
+  }
+}
+```
+
+## `loadTemplates`
+
+```js
+async function makeEnv() {
+  const templates = await owl.utils.loadTemplates("templates.xml");
+  const qweb = new owl.QWeb(templates);
+  return { qweb };
+}
+```
+
+## `escape`
+
+## `debounce`
@@ -1,11 +1,8 @@
 {
  "name": "owl-framework",
-  "version": "1.0.0-beta2",
+  "version": "0.22.0",
  "description": "Odoo Web Library (OWL)",
  "main": "src/index.ts",
-  "engines": {
-    "node": ">=10.15.3"
-  },
  "scripts": {
    "build:js": "tsc --target esnext --module es6 --outDir dist/owl",
    "build:bundle": "rollup -c",
@@ -17,8 +14,7 @@
    "tools:serve": "python3 tools/server.py || python tools/server.py",
    "tools": "npm run build && npm run tools:serve",
    "pretools:watch": "npm run build",
-    "tools:watch": "npm-run-all  --parallel tools:serve \"build:* -- --watch\"",
-    "prettier": "prettier {src/*.ts,src/**/*.ts,tests/*.ts,tests/**/*.ts,doc/*.md,doc/**/*.md} --write"
+    "tools:watch": "npm-run-all  --parallel tools:serve \"build:* -- --watch\""
  },
  "repository": {
    "type": "git",
@@ -39,13 +35,12 @@
    "jest-environment-jsdom": "^24.7.1",
    "live-server": "^1.2.1",
    "npm-run-all": "^4.1.5",
-    "prettier": "^1.19.1",
    "rollup": "^1.6.0",
    "rollup-plugin-typescript2": "^0.20.1",
    "sass": "^1.16.1",
    "source-map-support": "^0.5.10",
    "ts-jest": "^23.10.5",
-    "typescript": "^3.7.2",
+    "typescript": "^3.2.2",
    "uglify-es": "^3.3.9"
  },
  "jest": {
@@ -1,41 +0,0 @@
-# 🦉 OWL Roadmap 🦉
-
- Current version: 1.0.0-beta2
- Status: mostly stable
-
-This roadmap is only an attempt at predicting Owl's future.  Everything may
-change!
-
-
-
-### December 2019
-
-If all goes well, Owl is upgraded to beta status. From now on, no API change,
-even small, is expected (but it still could happen).
-
-### End of 2019
-
-Release v1.0
-
- API should be stable,
- we will use semantic versioning,
- we will maintain a changelog and an upgrade guide.
-
-### 1.x
-
- add chrome and firefox devtools,
- add support for single file components,
- fix every bugs,
- improve documentation,
- small backward compatible improvements.
-
-### 2.x (2021? 2022?)
-
-Maybe:
-
- reimplement vdom to use *block* system, like Vue 3, which should make Owl
-  much faster
- refactor `QWeb` to use an intermediate representation (some kind of AST) to
-  allow additional optimisations.
-
-
@@ -1,11 +1,8 @@
 import { Observer } from "../core/observer";
-import { OwlEvent } from "../core/owl_event";
 import { CompiledTemplate, QWeb } from "../qweb/index";
-import { patch, VNode } from "../vdom/index";
+import { h, patch, VNode } from "../vdom/index";
 import "./directive";
-import { Fiber } from "./fiber";
 import "./props_validation";
-import { Scheduler, scheduler } from "./scheduler";

 /**
 * Owl Component System
@@ -14,6 +11,7 @@ import { Scheduler, scheduler } from "./scheduler";
 * contains:
 *
 * - the Env interface (generic type for the environment)
+ * - the Fiber interface (owl metadata attached to a rendering)
 * - the Internal interface (the owl specific metadata attached to a component)
 * - the Component class
 */
@@ -36,8 +34,25 @@ export interface Env {
  [key: string]: any;
 }

-interface MountOptions {
-  position?: "first-child" | "last-child" | "self";
+/**
+ * Fibers are small abstractions designed to contain all the internal state
+ * associated to a "rendering work unit", relative to a specific component.
+ *
+ * A rendering will cause the creation of a fiber for each impacted components.
+ */
+export interface Fiber<Props> {
+  force: boolean;
+  rootFiber: Fiber<any> | null;
+  isCancelled: boolean;
+  scope: any;
+  vars: any;
+  patchQueue: Fiber<any>[];
+  component: Component<any, any>;
+  vnode: VNode | null;
+  props: Props;
+  promise: Promise<VNode> | null;
+  //   handlers?: any;
+  //   mountedHandlers?: any;
 }

 /**
@@ -49,9 +64,7 @@ interface Internal<T extends Env, Props> {
  // each component has a unique id, useful mostly to handle parent/child
  // relationships
  readonly id: number;
-  depth: number;
  vnode: VNode | null;
-  pvnode: VNode | null;
  isMounted: boolean;
  isDestroyed: boolean;

@@ -64,31 +77,19 @@ interface Internal<T extends Env, Props> {
  // the component instance back whenever the template is rerendered.
  cmap: { [key: number]: number };

-  currentFiber: Fiber | null;
-  // parentLastFiberId is there to help the parent component to detect, among
-  // its children, those that are not used anymore and thus can be destroyed
-  parentLastFiberId: number;
-
-  // when a rendering is initiated by a parent, it may set variables in 'scope'
-  // (typically when the component is rendered in a slot). We need to
-  // store that information in case the component would be re-rendered later on.
-  scope: any;
+  currentFiber: Fiber<Props> | null;

  boundHandlers: { [key: number]: any };
  observer: Observer | null;
-  renderFn: CompiledTemplate;
+  render: CompiledTemplate | null;
  mountedCB: Function | null;
  willUnmountCB: Function | null;
  willPatchCB: Function | null;
  patchedCB: Function | null;
-  willStartCB: Function | null;
-  willUpdatePropsCB: Function | null;
  classObj: { [key: string]: boolean } | null;
  refs: { [key: string]: Component<T, any> | HTMLElement | undefined } | null;
 }

-export const portalSymbol = Symbol("portal"); // FIXME
-
 //------------------------------------------------------------------------------
 // Component
 //------------------------------------------------------------------------------
@@ -98,14 +99,10 @@ export class Component<T extends Env, Props extends {}> {
  readonly __owl__: Internal<Env, Props>;
  static template?: string | null = null;
  static _template?: string | null = null;
-  static current: Component<any, any> | null = null;
+  static _current?: any | null = null;
  static components = {};
  static props?: any;
  static defaultProps?: any;
-  static env: any = {};
-  // expose scheduler s.t. it can be mocked for testing purposes
-  static scheduler: Scheduler = scheduler;
-  __target: HTMLElement | undefined;

  /**
   * The `el` is the root element of the component.  Note that it could be null:
@@ -125,36 +122,45 @@ export class Component<T extends Env, Props extends {}> {
  /**
   * Creates an instance of Component.
   *
+   * The root component of a component tree needs an environment:
+   *
+   * ```javascript
+   *   const root = new RootComponent(env, props);
+   * ```
+   *
+   * Every other component simply needs a reference to its parent:
+   *
+   * ```javascript
+   *   const child = new SomeComponent(parent, props);
+   * ```
+   *
   * Note that most of the time, only the root component needs to be created by
   * hand.  Other components should be created automatically by the framework (with
   * the t-component directive in a template)
   */
-  constructor(parent?: Component<T, any> | null, props?: Props) {
-    Component.current = this;
-
-    let constr = this.constructor as any;
-    const defaultProps = constr.defaultProps;
+  constructor(parent: Component<T, any> | T, props?: Props) {
+    const defaultProps = (<any>this.constructor).defaultProps;
+    Component._current = this;
    if (defaultProps) {
-      props = props || ({} as Props);
-      this.__applyDefaultProps(props, defaultProps);
+      props = this.__applyDefaultProps(props, defaultProps);
    }
-    this.props = <Props>props;
-    if (QWeb.dev) {
-      QWeb.utils.validateProps(constr, this.props);
-    }
-
-    const id: number = nextId++;
-    let depth;
-    if (parent) {
+    // is this a good idea?
+    //   Pro: if props is empty, we can create easily a component
+    //   Con: this is not really safe
+    //   Pro: but creating component (by a template) is always unsafe anyway
+    this.props = <Props>props || <Props>{};
+    let id: number = nextId++;
+    let p: Component<T, any> | null = null;
+    if (parent instanceof Component) {
+      p = parent;
      this.env = parent.env;
-      const __powl__ = parent.__owl__;
-      __powl__.children[id] = this;
-      depth = __powl__.depth + 1;
+      parent.__owl__.children[id] = this;
    } else {
-      // we are the root component
-      this.env = (this.constructor as any).env;
-      if (!this.env.qweb) {
-        this.env.qweb = new QWeb();
+      this.env = parent;
+      if (QWeb.dev) {
+        // we only validate props for root widgets here.  "Regular" widget
+        // props are validated by the t-component directive
+        QWeb.utils.validateProps(this.constructor, this.props);
      }
      this.env.qweb.on("update", this, () => {
        if (this.__owl__.isMounted) {
@@ -169,35 +175,25 @@ export class Component<T extends Env, Props extends {}> {
          this.env.qweb.off("update", this);
        }
      });
-      depth = 0;
    }
-
-    const qweb = this.env.qweb;
-    const template = constr.template || this.__getTemplate(qweb);
    this.__owl__ = {
      id: id,
-      depth: depth,
      vnode: null,
-      pvnode: null,
      isMounted: false,
      isDestroyed: false,
-      parent: parent || null,
+      parent: p,
      children: {},
      cmap: {},
      currentFiber: null,
-      parentLastFiberId: 0,
      boundHandlers: {},
      mountedCB: null,
      willUnmountCB: null,
      willPatchCB: null,
      patchedCB: null,
-      willStartCB: null,
-      willUpdatePropsCB: null,
      observer: null,
-      renderFn: qweb.render.bind(qweb, template),
+      render: null,
      classObj: null,
-      refs: null,
-      scope: null
+      refs: null
    };
  }

@@ -276,11 +272,8 @@ export class Component<T extends Env, Props extends {}> {
  /**
   * catchError is a method called whenever some error happens in the rendering or
   * lifecycle hooks of a child.
-   *
-   * It needs to be implemented by a component that is designed to handle the
-   * error properly.
   */
-  catchError?(error?: Error): void;
+  catchError(error: Error): void {}

  //--------------------------------------------------------------------------
  // Public
@@ -294,34 +287,31 @@ export class Component<T extends Env, Props extends {}> {
   *
   * Note that a component can be mounted an unmounted several times
   */
-  async mount(target: HTMLElement | DocumentFragment, options: MountOptions = {}): Promise<void> {
-    const position = options.position || "last-child";
+  async mount(target: HTMLElement, renderBeforeRemount: boolean = false): Promise<void> {
    const __owl__ = this.__owl__;
    if (__owl__.isMounted) {
-      return Promise.resolve();
+      return;
    }
-    if (!(target instanceof HTMLElement || target instanceof DocumentFragment)) {
-      let message = `Component '${this.constructor.name}' cannot be mounted: the target is not a valid DOM node.`;
-      message += `\nMaybe the DOM is not ready yet? (in that case, you can use owl.utils.whenReady)`;
-      throw new Error(message);
-    }
-    let inserter =
-      position === "last-child"
-        ? el => target.appendChild(el)
-        : position === "first-child"
-        ? el => target.prepend(el)
-        : el => {};
-    if (position === "self") {
-      this.__target = target as HTMLElement;
-    }
-    const fiber = new Fiber(null, this, false, inserter);
-    fiber.shouldPatch = false;
+    const fiber = this.__createFiber(false, undefined, undefined, undefined);
    if (!__owl__.vnode) {
-      this.__prepareAndRender(fiber, () => {});
-    } else {
-      this.__render(fiber);
+      fiber.promise = this.__prepareAndRender(fiber);
+      const vnode = await fiber.promise;
+      if (__owl__.isDestroyed) {
+        // component was destroyed before we get here...
+        return;
+      }
+      this.__patch(vnode);
+    } else if (renderBeforeRemount) {
+      fiber.patchQueue.push(fiber);
+      fiber.promise = this.__render(fiber);
+      await fiber.promise;
+      this.__applyPatchQueue(fiber);
+    }
+    target.appendChild(this.el!);
+
+    if (document.body.contains(target)) {
+      this.__callMounted();
    }
-    return scheduler.addFiber(fiber);
  }

  /**
@@ -346,34 +336,19 @@ export class Component<T extends Env, Props extends {}> {
   */
  async render(force: boolean = false): Promise<void> {
    const __owl__ = this.__owl__;
-    if (!__owl__.isMounted && !__owl__.currentFiber) {
-      // if we get here, this means that the component was either never mounted,
-      // or was unmounted and some state change  triggered a render. Either way,
-      // we do not want to actually render anything in this case.
+    if (!__owl__.isMounted) {
      return;
    }
-    if (__owl__.currentFiber && !__owl__.currentFiber.isRendered) {
-      return scheduler.addFiber(__owl__.currentFiber.root);
+    const fiber = this.__createFiber(force, undefined, undefined, undefined);
+    fiber.patchQueue.push(fiber);
+    fiber.promise = this.__render(fiber);
+    await fiber.promise;
+
+    if (__owl__.isMounted && fiber === __owl__.currentFiber) {
+      // we only update the vnode and the actual DOM if no other rendering
+      // occurred between now and when the render method was initially called.
+      this.__applyPatchQueue(fiber);
    }
-    // if we aren't mounted at this point, it implies that there is a
-    // currentFiber that is already rendered (isRendered is true), so we are
-    // about to be mounted
-    const isMounted = __owl__.isMounted;
-    const fiber = new Fiber(null, this, force, null);
-    Promise.resolve().then(() => {
-      if (__owl__.isMounted || !isMounted) {
-        // we are mounted (__owl__.isMounted), or if we are currently being
-        // mounted (!isMounted), so we call __render
-        this.__render(fiber);
-      } else {
-        // we were mounted when render was called, but we aren't anymore, so we
-        // were actually about to be unmounted ; we can thus forget about this
-        // fiber
-        fiber.isCompleted = true;
-        __owl__.currentFiber = null;
-      }
-    });
-    return scheduler.addFiber(fiber);
  }

  /**
@@ -412,13 +387,41 @@ export class Component<T extends Env, Props extends {}> {
   * willUnmount().
   */
  trigger(eventType: string, payload?: any) {
-    this.__trigger(this, eventType, payload);
+    if (this.el) {
+      const ev = new CustomEvent(eventType, {
+        bubbles: true,
+        cancelable: true,
+        detail: payload
+      });
+      this.el.dispatchEvent(ev);
+    }
  }

  //--------------------------------------------------------------------------
  // Private
  //--------------------------------------------------------------------------

+  /**
+   * This method is a helper to create a fiber element.
+   */
+  __createFiber(force, scope, vars, parent?: Fiber<any>): Fiber<Props> {
+    const fiber: Fiber<Props> = {
+      force,
+      scope,
+      vars,
+      rootFiber: null,
+      isCancelled: false,
+      component: this,
+      vnode: null,
+      patchQueue: parent ? parent.patchQueue : [],
+      props: this.props,
+      promise: null
+    };
+    fiber.rootFiber = parent ? parent.rootFiber : fiber;
+    this.__owl__.currentFiber = fiber;
+    return fiber;
+  }
+
  /**
   * Private helper to perform a full destroy, from the point of view of an Owl
   * component. It does not remove the el (this is done only once on the top
@@ -434,9 +437,6 @@ export class Component<T extends Env, Props extends {}> {
    const __owl__ = this.__owl__;
    const isMounted = __owl__.isMounted;
    if (isMounted) {
-      if (__owl__.willUnmountCB) {
-        __owl__.willUnmountCB();
-      }
      this.willUnmount();
      __owl__.isMounted = false;
    }
@@ -451,19 +451,25 @@ export class Component<T extends Env, Props extends {}> {
    }
    __owl__.isDestroyed = true;
    delete __owl__.vnode;
-    if (__owl__.currentFiber) {
-      __owl__.currentFiber.isCompleted = true;
-    }
  }

  __callMounted() {
    const __owl__ = this.__owl__;
-
+    const children = __owl__.children;
+    for (let id in children) {
+      const comp = children[id];
+      if (!comp.__owl__.isMounted && this.el!.contains(comp.el)) {
+        comp.__callMounted();
+      }
+    }
    __owl__.isMounted = true;
-    __owl__.currentFiber = null;
-    this.mounted();
-    if (__owl__.mountedCB) {
-      __owl__.mountedCB();
+    try {
+      this.mounted();
+      if (__owl__.mountedCB) {
+          __owl__.mountedCB()
+      }
+    } catch (e) {
+      errorHandler(e, this);
    }
  }

@@ -474,10 +480,6 @@ export class Component<T extends Env, Props extends {}> {
    }
    this.willUnmount();
    __owl__.isMounted = false;
-    if (this.__owl__.currentFiber) {
-      this.__owl__.currentFiber.isCompleted = true;
-      this.__owl__.currentFiber.root.counter = 0;
-    }
    const children = __owl__.children;
    for (let id in children) {
      const comp = children[id];
@@ -486,58 +488,29 @@ export class Component<T extends Env, Props extends {}> {
      }
    }
  }
-  /**
-   * Private trigger method, allows to choose the component which triggered
-   * the event in the first place
-   */
-  __trigger(component: Component<any, any>, eventType: string, payload?: any) {
-    if (this.el) {
-      const ev = new OwlEvent(component, eventType, {
-        bubbles: true,
-        cancelable: true,
-        detail: payload
-      });
-      const triggerHook = this.env[portalSymbol as any];
-      if (triggerHook) {
-        triggerHook(ev);
-      }
-      this.el.dispatchEvent(ev);
-    }
-  }
+
  /**
   * The __updateProps method is called by the t-component directive whenever
   * it updates a component (so, when the parent template is rerendered).
   */
-  async __updateProps(nextProps: Props, parentFiber: Fiber, scope: any): Promise<void> {
-    this.__owl__.scope = scope;
+  async __updateProps(
+    nextProps: Props,
+    parentFiber: Fiber<any>,
+    scope?: any,
+    vars?: any
+  ): Promise<void> {
    const shouldUpdate = parentFiber.force || this.shouldUpdate(nextProps);
    if (shouldUpdate) {
-      const __owl__ = this.__owl__;
-      const fiber = new Fiber(parentFiber, this, parentFiber.force, null);
-      if (!parentFiber.child) {
-        parentFiber.child = fiber;
-      } else {
-        parentFiber.lastChild!.sibling = fiber;
-      }
-      parentFiber.lastChild = fiber;
-
      const defaultProps = (<any>this.constructor).defaultProps;
      if (defaultProps) {
-        this.__applyDefaultProps(nextProps, defaultProps);
-      }
-      if (QWeb.dev) {
-        QWeb.utils.validateProps(this.constructor, nextProps);
-      }
-      await Promise.all([
-        this.willUpdateProps(nextProps),
-        __owl__.willUpdatePropsCB && __owl__.willUpdatePropsCB(nextProps)
-      ]);
-      if (fiber.isCompleted) {
-        return;
+        nextProps = this.__applyDefaultProps(nextProps, defaultProps);
      }
+      await this.willUpdateProps(nextProps);
      this.props = nextProps;
+      const fiber = this.__createFiber(parentFiber.force, scope, vars, parentFiber);
+      fiber.patchQueue.push(fiber);

-      this.__render(fiber);
+      await this.__render(fiber);
    }
  }

@@ -545,120 +518,112 @@ export class Component<T extends Env, Props extends {}> {
   * Main patching method. We call the virtual dom patch method here to convert
   * a virtual dom vnode into some actual dom.
   */
-  __patch(vnode: VNode) {
+  __patch(vnode) {
    const __owl__ = this.__owl__;
-    if (this.__target) {
-      if (this.__target.tagName.toLowerCase() !== vnode.sel) {
-        throw new Error(
-          `Cannot attach '${this.constructor.name}' to target node (not same tag name)`
-        );
-      }
-      __owl__.vnode = patch(this.__target, vnode);
-      delete this.__target;
-    } else {
-      const target = __owl__.vnode || document.createElement(vnode.sel!);
-      __owl__.vnode = patch(target, vnode);
-    }
+    const target = __owl__.vnode || document.createElement(vnode.sel!);
+    __owl__.vnode = patch(target, vnode);
  }

  /**
   * The __prepare method is only called by the t-component directive, when a
-   * subcomponent is created. It gets its scope, if any, from the
+   * subcomponent is created. It gets its scope and vars, if any, from the
   * parent template.
   */
-  __prepare(parentFiber: Fiber, scope: any, cb: CallableFunction): Fiber {
-    this.__owl__.scope = scope;
-    const fiber = new Fiber(parentFiber, this, parentFiber.force, null);
-    fiber.shouldPatch = false;
-    if (!parentFiber.child) {
-      parentFiber.child = fiber;
-    } else {
-      parentFiber.lastChild!.sibling = fiber;
-    }
-    parentFiber.lastChild = fiber;
-    this.__prepareAndRender(fiber, cb);
-    return fiber;
+  __prepare(parentFiber: Fiber<any>, scope: any, vars: any): Promise<VNode> {
+    const fiber = this.__createFiber(parentFiber.force, scope, vars, parentFiber);
+    fiber.promise = this.__prepareAndRender(fiber);
+    return fiber.promise;
  }

-  __getTemplate(qweb: QWeb): string {
-    let p = (<any>this).constructor;
-    if (!p.hasOwnProperty("_template")) {
-      // here, the component and none of its superclasses defines a static `template`
-      // key. So we fall back on looking for a template matching its name (or
-      // one of its subclass).
-
-      let template: string;
-      while ((template = p.name) && !(template in qweb.templates) && p !== Component) {
-        p = p.__proto__;
-      }
-      if (p === Component) {
-        throw new Error(`Could not find template for component "${this.constructor.name}"`);
-      } else {
-        p._template = template;
-      }
-    }
-    return p._template;
-  }
-  async __prepareAndRender(fiber: Fiber, cb: CallableFunction) {
+  async __prepareAndRender(fiber: Fiber<Props>): Promise<VNode> {
    try {
-      await Promise.all([this.willStart(), this.__owl__.willStartCB && this.__owl__.willStartCB()]);
+      await this.willStart();
    } catch (e) {
-      fiber.handleError(e);
-      return Promise.resolve();
+      errorHandler(e, this);
+      return Promise.resolve(h("div"));
    }
-    if (this.__owl__.isDestroyed) {
-      return Promise.resolve();
+    const __owl__ = this.__owl__;
+    if (__owl__.isDestroyed) {
+      return Promise.resolve(h("div"));
    }
-    if (!fiber.isCompleted) {
-      this.__render(fiber);
-      cb();
+    const qweb = this.env.qweb;
+    let p = (<any>this).constructor;
+    // console.warn(p, p.template, p._template, 'template' in p, p.hasOwnProperty('template'))
+    if (!p.hasOwnProperty("_template")) {
+      if (p.template) {
+        p._template = p.template;
+      } else {
+        // here, the component and none of its superclasses defines a static `template`
+        // key. So we fall back on looking for a template matching its name (or
+        // one of its subclass).
+
+        let template: string;
+        while ((template = p.name) && !(template in qweb.templates) && p !== Component) {
+          p = p.__proto__;
+        }
+        if (p === Component) {
+          throw new Error(`Could not find template for component "${this.constructor.name}"`);
+        } else {
+          p._template = template;
+        }
+      }
    }
+    __owl__.render = qweb.render.bind(qweb, p._template);
+    return this.__render(fiber);
  }

-  __render(fiber: Fiber) {
+  __render(fiber: Fiber<Props>): Promise<VNode> {
    const __owl__ = this.__owl__;
+    const promises: Promise<void>[] = [];
    if (__owl__.observer) {
      __owl__.observer.allowMutations = false;
    }
-    let error;
+    let vnode;
    try {
-      let vnode = __owl__.renderFn!(this, {
+      vnode = __owl__.render!(this, {
+        promises,
        handlers: __owl__.boundHandlers,
        fiber: fiber
      });
-      // we iterate over the children to detect those that no longer belong to the
-      // current rendering: those ones, if not mounted yet, can (and have to) be
-      // destroyed right now, because they are not in the DOM, and thus we won't
-      // be notified later on (when patching), that they are removed from the DOM
-      for (let childKey in __owl__.children) {
-        let child = __owl__.children[childKey];
-        if (!child.__owl__.isMounted && child.__owl__.parentLastFiberId < fiber.id) {
-          child.destroy();
-        }
-      }
-      if (!vnode) {
-        throw new Error(`Rendering '${this.constructor.name}' did not return anything`);
-      }
-      fiber.vnode = vnode;
-      // we apply here the class information described on the component by the
-      // template (so, something like <MyComponent class="..."/>) to the actual
-      // root vnode
-      if (__owl__.classObj) {
-        const data = vnode.data!;
-        data.class = Object.assign(data.class || {}, __owl__.classObj);
-      }
    } catch (e) {
-      error = e;
+      vnode = __owl__.vnode || h("div");
+      errorHandler(e, this);
    }
+    fiber.vnode = vnode;
    if (__owl__.observer) {
      __owl__.observer.allowMutations = true;
    }

-    fiber.root.counter--;
-    fiber.isRendered = true;
-    if (error) {
-      fiber.handleError(error);
+    // this part is critical for the patching process to be done correctly. The
+    // tricky part is that a child component can be rerendered on its own, which
+    // will update its own vnode representation without the knowledge of the
+    // parent component.  With this, we make sure that the parent component will be
+    // able to patch itself properly after
+    vnode.key = __owl__.id;
+
+    // we applly here the class information described on the component by the
+    // template (so, something like <MyComponent class="..."/>) to the actual
+    // root vnode
+    if (__owl__.classObj) {
+      vnode.data.class = Object.assign(vnode.data.class || {}, __owl__.classObj);
    }
+
+    return Promise.all(promises).then(() => vnode);
+  }
+
+  /**
+   * Only called by qweb t-component directive
+   */
+  __mount(vnode: VNode, elm: HTMLElement): VNode {
+    const __owl__ = this.__owl__;
+    if (__owl__.classObj) {
+      (<any>vnode).data.class = Object.assign((<any>vnode).data.class || {}, __owl__.classObj);
+    }
+    __owl__.vnode = patch(elm, vnode);
+    if (__owl__.parent!.__owl__.isMounted && !__owl__.isMounted) {
+      this.__callMounted();
+    }
+    return __owl__.vnode;
  }

  /**
@@ -675,13 +640,84 @@ export class Component<T extends Env, Props extends {}> {
  /**
   * Apply default props (only top level).
   *
-   * Note that this method does modify in place the props
+   * Note that this method does not modify in place the props, it returns a new
+   * prop object
   */
-  __applyDefaultProps(props: Object, defaultProps: Object) {
+  __applyDefaultProps(props: Object | undefined, defaultProps: Object): Props {
+    props = props ? Object.assign({}, props) : {};
    for (let propName in defaultProps) {
      if (props![propName] === undefined) {
        props![propName] = defaultProps[propName];
      }
    }
+    return <Props>props;
+  }
+
+  /**
+   * Apply the given patch queue from a fiber.
+   *   1) Call 'willPatch' on the component of each patch
+   *   2) Call '__patch' on the component of each patch
+   *   3) Call 'patched' on the component of each patch, in reverse order
+   */
+  __applyPatchQueue(fiber: Fiber<Props>) {
+    const patchQueue = fiber.patchQueue;
+    let component: Component<any, any> = this;
+    try {
+      const patchLen = patchQueue.length;
+      for (let i = 0; i < patchLen; i++) {
+        component = patchQueue[i].component;
+        if (component.__owl__.willPatchCB) {
+          component.__owl__.willPatchCB();
+        }
+        component.willPatch();
+      }
+      for (let i = 0; i < patchLen; i++) {
+        const fiber = patchQueue[i];
+        component = fiber.component;
+        component.__patch(fiber.vnode);
+      }
+      for (let i = patchLen - 1; i >= 0; i--) {
+        component = patchQueue[i].component;
+        component.patched();
+        if (component.__owl__.patchedCB) {
+          component.__owl__.patchedCB();
+        }
+      }
+    } catch (e) {
+      errorHandler(e, component);
+    }
+  }
+}
+
+//------------------------------------------------------------------------------
+// Error handling
+//------------------------------------------------------------------------------
+
+/**
+ * This is the global error handler for errors occurring in Owl main lifecycle
+ * methods.  Caught errors are triggered on the QWeb instance, and are
+ * potentially given to some parent component which implements `catchError`.
+ *
+ * If there are no such component, we destroy everything. This is better than
+ * being in a corrupted state.
+ */
+function errorHandler(error: Error, component: Component<any, any>) {
+  let canCatch = false;
+  let qweb = component.env.qweb;
+  let root = component;
+  while (component && !(canCatch = component.catchError !== Component.prototype.catchError)) {
+    root = component;
+    component = component.__owl__.parent!;
+  }
+  console.error(error);
+  // we trigger error on QWeb so it can be logged/handled
+  qweb.trigger("error", error);
+
+  if (canCatch) {
+    setTimeout(() => {
+      component.catchError(error);
+    });
+  } else {
+    root.destroy();
  }
 }
@@ -1,5 +1,5 @@
 import { QWeb } from "../qweb/index";
-import { INTERP_REGEXP } from "../qweb/compilation_context";
+import { INTERP_REGEXP } from "../qweb/context";
 import { MODS_CODE } from "../qweb/extensions";

 //------------------------------------------------------------------------------
@@ -186,15 +186,17 @@ QWeb.utils.defineProxy = function defineProxy(target, source) {

 QWeb.addDirective({
  name: "component",
-  extraNames: ["props"],
+  extraNames: ["props", "keepalive", "asyncroot"],
  priority: 100,
  atNodeEncounter({ ctx, value, node, qweb }): boolean {
    ctx.addLine("//COMPONENT");
+    ctx.rootContext.shouldDefineOwner = true;
    ctx.rootContext.shouldDefineQWeb = true;
    ctx.rootContext.shouldDefineParent = true;
    ctx.rootContext.shouldDefineUtils = true;
-    ctx.rootContext.shouldDefineScope = true;
+    let keepAlive = node.getAttribute("t-keepalive") ? true : false;
    let hasDynamicProps = node.getAttribute("t-props") ? true : false;
+    let async = node.getAttribute("t-asyncroot") ? true : false;

    // t-on- events and t-transition
    const events: [string, string[], string, string][] = [];
@@ -207,11 +209,11 @@ QWeb.addDirective({
      if (name.startsWith("t-on-")) {
        const [eventName, ...mods] = name.slice(5).split(".");
        let extraArgs;
-        let handlerValue = value.replace(/\(.*\)/, function(args) {
+        let handlerName = value.replace(/\(.*\)/, function(args) {
          extraArgs = args.slice(1, -1);
          return "";
        });
-        events.push([eventName, mods, handlerValue, extraArgs]);
+        events.push([eventName, mods, handlerName, extraArgs]);
      } else if (name === "t-transition") {
        transition = value;
      } else if (!name.startsWith("t-")) {
@@ -222,13 +224,41 @@ QWeb.addDirective({
      }
    }

+    let key = node.getAttribute("t-key");
+    if (key) {
+      key = ctx.formatExpression(key);
+    }
+
    // computing the props string representing the props object
    let propStr = Object.keys(props)
      .map(k => k + ":" + props[k])
      .join(",");
+    let dummyID = ctx.generateID();
+    let defID = ctx.generateID();
    let componentID = ctx.generateID();
+    let keyID = key && ctx.generateID();
+    if (key) {
+      // we bind a variable to the key (could be a complex expression, so we
+      // want to evaluate it only once)
+      ctx.addLine(`let key${keyID} = 'key' + ${key};`);
+    }
+    ctx.addLine(`let def${defID};`);
+    let templateID = key
+      ? `key${keyID}`
+      : ctx.inLoop
+      ? ctx.currentKey
+        ? `String(${ctx.currentKey} + '_k_' + i + '_c_' + ${componentID} )`
+        : `String(-${componentID} - i)`
+      : String(componentID);
+    if (ctx.allowMultipleRoots) {
+      templateID = `"_slot_${templateID}"`;
+    }
+    if (key || ctx.inLoop) {
+      let id = ctx.generateID();
+      ctx.addLine(`let templateId${id} = ${templateID};`);
+      templateID = `templateId${id}`;
+    }

-    const templateKey = ctx.generateTemplateKey();
    let ref = node.getAttribute("t-ref");
    let refExpr = "";
    let refKey: string = "";
@@ -238,15 +268,18 @@ QWeb.addDirective({
      ctx.addLine(`const ${refKey} = ${ctx.interpolate(ref)};`);
      refExpr = `context.__owl__.refs[${refKey}] = w${componentID};`;
    }
-    let finalizeComponentCode = `w${componentID}.destroy();`;
-    if (ref) {
+    let transitionsInsertCode = "";
+    if (transition) {
+      transitionsInsertCode = `utils.transitionInsert(vn, '${transition}');`;
+    }
+    let finalizeComponentCode = `w${componentID}.${keepAlive ? "unmount" : "destroy"}();`;
+    if (ref && !keepAlive) {
      finalizeComponentCode += `delete context.__owl__.refs[${refKey}];`;
    }
    if (transition) {
      finalizeComponentCode = `let finalize = () => {
          ${finalizeComponentCode}
        };
-        delete w${componentID}.__owl__.transitionInserted;
        utils.transitionRemove(vn, '${transition}', finalize);`;
    }

@@ -284,31 +317,32 @@ QWeb.addDirective({
        }
      }
      let eventsCode = events
-        .map(function([eventName, mods, handlerValue, extraArgs]) {
-          let params = "context";
+        .map(function([eventName, mods, handlerName, extraArgs]) {
+          let params = "owner";
          if (extraArgs) {
-            if (ctx.loopNumber) {
+            if (ctx.inLoop) {
              let argId = ctx.generateID();
              // we need to evaluate the arguments now, because the handler will
              // be set asynchronously later when the widget is ready, and the
              // context might be different.
              ctx.addLine(`let arg${argId} = ${ctx.formatExpression(extraArgs)};`);
-              params = `context, arg${argId}`;
+              params = `owner, arg${argId}`;
            } else {
-              params = `context, ${ctx.formatExpression(extraArgs)}`;
+              params = `owner, ${ctx.formatExpression(extraArgs)}`;
            }
          }
-          let handler = `function (e) {if(!context.__owl__.isMounted){return}`;
-          handler += mods
-            .map(function(mod) {
-              return T_COMPONENT_MODS_CODE[mod];
-            })
-            .join("");
-          if (handlerValue) {
-            handler += `const fn = context['${handlerValue}'];`;
-            handler += `if (fn) { fn.call(${params}, e); } else { context.${handlerValue}; }`;
+          let handler;
+          if (mods.length > 0) {
+            handler = `function (e) {`;
+            handler += mods
+              .map(function(mod) {
+                return T_COMPONENT_MODS_CODE[mod];
+              })
+              .join("");
+            handler += `owner['${handlerName}'].call(${params}, e);}`;
+          } else {
+            handler = `owner['${handlerName}'].bind(${params})`;
          }
-          handler += `}`;
          return `vn.elm.addEventListener('${eventName}', ${handler});`;
        })
        .join("");
@@ -318,16 +352,32 @@ QWeb.addDirective({
    }

    ctx.addLine(
-      `let w${componentID} = ${templateKey} in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[${templateKey}]] : false;`
+      `let w${componentID} = ${templateID} in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[${templateID}]] : false;`
    );
-    let shouldProxy = !ctx.parentNode;
-    if (shouldProxy) {
-      let id = ctx.generateID();
-      ctx.rootContext.rootNode = id;
-      shouldProxy = true;
-      ctx.rootContext.shouldDefineResult = true;
-      ctx.addLine(`let vn${id} = {};`);
-      ctx.addLine(`result = vn${id};`);
+    if (ctx.parentNode) {
+      ctx.addLine(`let _${dummyID}_index = c${ctx.parentNode}.length;`);
+    }
+    let shouldProxy = false;
+    if (async || keepAlive) {
+      ctx.addLine(
+        `const fiber${componentID} = Object.assign(Object.create(extra.fiber), {patchQueue: []});`
+      );
+    }
+    if (async) {
+      ctx.addLine(
+        `c${ctx.parentNode}.push(w${componentID} && w${componentID}.__owl__.pvnode || null);`
+      );
+    } else {
+      if (ctx.parentNode) {
+        ctx.addLine(`c${ctx.parentNode}.push(null);`);
+      } else {
+        let id = ctx.generateID();
+        ctx.rootContext.rootNode = id;
+        shouldProxy = true;
+        ctx.rootContext.shouldDefineResult = true;
+        ctx.addLine(`let vn${id} = {};`);
+        ctx.addLine(`result = vn${id};`);
+      }
    }
    if (hasDynamicProps) {
      const dynamicProp = ctx.formatExpression(node.getAttribute("t-props")!);
@@ -338,40 +388,17 @@ QWeb.addDirective({
    ctx.addIf(
      `w${componentID} && w${componentID}.__owl__.currentFiber && !w${componentID}.__owl__.vnode`
    );
+    ctx.addIf(
+      `utils.shallowEqual(props${componentID}, w${componentID}.__owl__.currentFiber.props)`
+    );
+    ctx.addLine(`def${defID} = w${componentID}.__owl__.currentFiber.promise;`);
+    ctx.addElse();
    ctx.addLine(`w${componentID}.destroy();`);
    ctx.addLine(`w${componentID} = false;`);
    ctx.closeIf();
+    ctx.closeIf();

-    let registerCode = "";
-    if (shouldProxy) {
-      registerCode = `utils.defineProxy(vn${ctx.rootNode}, pvnode);`;
-    }
-
-    // SLOTS
-    const hasSlots = node.childNodes.length;
-
-    let scope = hasSlots ? `Object.assign(Object.create(context), scope)` : "undefined";
-
-    ctx.addIf(`w${componentID}`);
-
-    // need to update component
-    let styleCode = "";
-    if (tattStyle) {
-      styleCode = `.then(()=>{if (w${componentID}.__owl__.isDestroyed) {return};w${componentID}.el.style=${tattStyle};});`;
-    }
-    ctx.addLine(
-      `w${componentID}.__updateProps(props${componentID}, extra.fiber, ${scope})${styleCode};`
-    );
-    ctx.addLine(`let pvnode = w${componentID}.__owl__.pvnode;`);
-    if (registerCode) {
-      ctx.addLine(registerCode);
-    }
-    if (ctx.parentNode) {
-      ctx.addLine(`c${ctx.parentNode}.push(pvnode);`);
-    }
-
-    ctx.addElse();
-
+    ctx.addIf(`!w${componentID}`);
    // new component
    let dynamicFallback = "";
    if (!value.match(INTERP_REGEXP)) {
@@ -387,16 +414,23 @@ QWeb.addDirective({
    ctx.addLine(
      `if (!W${componentID}) {throw new Error('Cannot find the definition of component "' + componentKey${componentID} + '"')}`
    );
-    ctx.addLine(`w${componentID} = new W${componentID}(parent, props${componentID});`);
-    if (transition) {
-      ctx.addLine(`const __patch${componentID} = w${componentID}.__patch;`);
-      ctx.addLine(
-        `w${componentID}.__patch = fiber => {__patch${componentID}.call(w${componentID}, fiber); if(!w${componentID}.__owl__.transitionInserted){w${componentID}.__owl__.transitionInserted = true;utils.transitionInsert(w${componentID}.__owl__.vnode, '${transition}');}};`
-      );
+    if (QWeb.dev) {
+      ctx.addLine(`utils.validateProps(W${componentID}, props${componentID})`);
    }
-    ctx.addLine(`parent.__owl__.cmap[${templateKey}] = w${componentID}.__owl__.id;`);
+    ctx.addLine(`w${componentID} = new W${componentID}(parent, props${componentID});`);
+    ctx.addLine(`parent.__owl__.cmap[${templateID}] = w${componentID}.__owl__.id;`);

+    // SLOTS
+    const varDefs: string[] = [];
+    const hasSlots = node.childNodes.length;
    if (hasSlots) {
+      ctx.rootContext.shouldTrackScope = true;
+      for (let v of Object.values(ctx.variables)) {
+        if (v["id"]) {
+          varDefs.push(v["id"]);
+        }
+      }
+
      const clone = <Element>node.cloneNode(true);
      const slotNodes = clone.querySelectorAll("[t-set]");
      const slotId = QWeb.nextSlotId++;
@@ -421,29 +455,67 @@ QWeb.addDirective({
      }
    }

-    ctx.addLine(
-      `let fiber = w${componentID}.__prepare(extra.fiber, ${scope}, () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; ${createHook}});`
-    );
+    let scopeVars;
+    if (hasSlots) {
+      let scope = ctx.scopeVars.length ? `Object.assign({}, scope)` : `{}`;
+      let vars = varDefs.length ? `{${varDefs.join(",")}}` : "undefined";
+      scopeVars = `${scope}, ${vars}`;
+    } else {
+      scopeVars = "undefined, undefined";
+    }
+    ctx.addLine(`def${defID} = w${componentID}.__prepare(extra.fiber, ${scopeVars});`);
    // hack: specify empty remove hook to prevent the node from being removed from the DOM
-    const insertHook = refExpr ? `insert(vn) {${refExpr}},` : "";
+    let registerCode = `c${ctx.parentNode}[_${dummyID}_index]=pvnode;`;
+    if (shouldProxy) {
+      registerCode = `utils.defineProxy(vn${ctx.rootNode}, pvnode);`;
+    }
    ctx.addLine(
-      `let pvnode = h('dummy', {key: ${templateKey}, hook: {${insertHook}remove() {},destroy(vn) {${finalizeComponentCode}}}});`
+      `def${defID} = def${defID}.then(vnode=>{if (w${componentID}.__owl__.isDestroyed){return}${createHook}let pvnode=h(vnode.sel, {key: ${templateID}, hook: {insert(vn) {let nvn=w${componentID}.__mount(vnode, pvnode.elm);pvnode.elm=nvn.elm;${refExpr}${transitionsInsertCode}},remove() {},destroy(vn) {${finalizeComponentCode}}}});${registerCode}w${componentID}.__owl__.pvnode = pvnode;});`
    );
-    if (registerCode) {
-      ctx.addLine(registerCode);
-    }
-    if (ctx.parentNode) {
-      ctx.addLine(`c${ctx.parentNode}.push(pvnode);`);
-    }
-    ctx.addLine(`w${componentID}.__owl__.pvnode = pvnode;`);

+    ctx.addElse();
+    // need to update component
+    let patchQueueCode = async || keepAlive ? `fiber${componentID}` : "extra.fiber";
+    if (keepAlive) {
+      // if we have t-keepalive="1", the component could be unmounted, but then
+      // we __updateProps is called.  This is ok, but we do not want to call
+      // the willPatch/patched hooks of the component in this case, so we
+      // disable the patch queue
+      patchQueueCode = `w${componentID}.__owl__.isMounted ? extra.fiber : fiber${componentID}`;
+    }
+    if (QWeb.dev) {
+      ctx.addLine(`utils.validateProps(w${componentID}.constructor, props${componentID})`);
+    }
+    ctx.addLine(
+      `def${defID} = def${defID} || w${componentID}.__updateProps(props${componentID}, ${patchQueueCode}${scopeVars &&
+        ", " + scopeVars});`
+    );
+    let keepAliveCode = "";
+    if (keepAlive) {
+      keepAliveCode = `pvnode.data.hook.insert = vn => {vn.elm.parentNode.replaceChild(w${componentID}.el,vn.elm);vn.elm=w${componentID}.el;w${componentID}.__remount();};`;
+    }
+    ctx.addLine(
+      `def${defID} = def${defID}.then(()=>{if (w${componentID}.__owl__.isDestroyed) {return};${
+        tattStyle ? `w${componentID}.el.style=${tattStyle};` : ""
+      }let pvnode=w${componentID}.__owl__.pvnode;${keepAliveCode}${registerCode}});`
+    );
    ctx.closeIf();

    if (classObj) {
      ctx.addLine(`w${componentID}.__owl__.classObj=${classObj};`);
    }

-    ctx.addLine(`w${componentID}.__owl__.parentLastFiberId = extra.fiber.id;`);
+    if (async) {
+      ctx.addLine(
+        `def${defID}.then(w${componentID}.__applyPatchQueue.bind(w${componentID}, fiber${componentID}));`
+      );
+    } else {
+      ctx.addLine(`extra.promises.push(def${defID});`);
+    }
+
+    if (node.hasAttribute("t-if") || node.hasAttribute("t-else") || node.hasAttribute("t-elif")) {
+      ctx.closeIf();
+    }

    return true;
  }
@@ -1,286 +0,0 @@
-import { h, VNode } from "../vdom/index";
-import { Component } from "./component";
-import { scheduler } from "./scheduler";
-
-/**
- * Owl Fiber Class
- *
- * Fibers are small abstractions designed to contain all the internal state
- * associated with a "rendering work unit", relative to a specific component.
- *
- * A rendering will cause the creation of a fiber for each impacted components.
- *
- * Fibers capture all that necessary information, which is critical to owl
- * asynchronous rendering pipeline. Fibers can be cancelled, can be in different
- * states and in general determine the state of the rendering.
- */
-
-export class Fiber {
-  static nextId: number = 1;
-  id: number = Fiber.nextId++;
-
-  // The force attribute determines if a rendering should bypass the `shouldUpdate`
-  // method potentially implemented by a component. It is usually set to false.
-  force: boolean;
-
-  // isCompleted means that the rendering corresponding to this fiber's work is
-  // done, either because the component has been mounted or patched, or because
-  // fiber has been cancelled.
-  isCompleted: boolean = false;
-
-  // the fibers corresponding to component updates (updateProps) need to call
-  // the willPatch and patched hooks from the corresponding component. However,
-  // fibers corresponding to a new component do not need to do that. So, the
-  // shouldPatch hook is the boolean that we check whenever we need to apply
-  // a patch.
-  shouldPatch: boolean = true;
-
-  // isRendered is the last state of a fiber. If true, this means that it has
-  // been rendered and is inert (so, it should not be taken into account when
-  // counting the number of active fibers).
-  isRendered: boolean = false;
-
-  // the counter number is a critical information. It is only necessary for a
-  // root fiber.  For that fiber, this number counts the number of active sub
-  // fibers.  When that number reaches 0, the fiber can be applied by the
-  // scheduler.
-  counter: number = 0;
-
-  inserter: (el: HTMLElement) => void | null;
-
-  scope: any;
-
-  component: Component<any, any>;
-  vnode: VNode | null = null;
-
-  root: Fiber;
-  child: Fiber | null = null;
-  sibling: Fiber | null = null;
-  lastChild: Fiber | null = null;
-  parent: Fiber | null = null;
-
-  error?: Error;
-
-  constructor(parent: Fiber | null, component: Component<any, any>, force, inserter) {
-    this.component = component;
-    this.force = force;
-    this.inserter = inserter;
-
-    const __owl__ = component.__owl__;
-    this.scope = __owl__.scope;
-
-    this.root = parent ? parent.root : this;
-    this.parent = parent;
-
-    let oldFiber = __owl__.currentFiber;
-    if (oldFiber && !oldFiber.isCompleted) {
-      if (oldFiber.root === oldFiber && !parent) {
-        // both oldFiber and this fiber are root fibers
-        this._reuseFiber(oldFiber);
-        return oldFiber;
-      } else {
-        this._remapFiber(oldFiber);
-      }
-    }
-
-    this.root.counter++;
-
-    __owl__.currentFiber = this;
-  }
-
-  /**
-   * When the oldFiber is not completed yet, and both oldFiber and this fiber
-   * are root fibers, we want to reuse the oldFiber instead of creating a new
-   * one. Doing so will guarantee that the initiator(s) of those renderings will
-   * be notified (the promise will resolve) when the last rendering will be done.
-   *
-   * This function thus assumes that oldFiber is a root fiber.
-   */
-  _reuseFiber(oldFiber: Fiber) {
-    oldFiber.cancel(); // cancel children fibers
-    oldFiber.isCompleted = false; // keep the root fiber alive
-    oldFiber.isRendered = false; // the fiber has to be re-rendered
-    if (oldFiber.child) {
-      // remove relation to children
-      oldFiber.child.parent = null;
-      oldFiber.child = null;
-      oldFiber.lastChild = null;
-    }
-    oldFiber.counter = 1; // re-initialize counter
-    oldFiber.id = Fiber.nextId++;
-  }
-
-  /**
-   * In some cases, a rendering initiated at some component can detect that it
-   * should be part of a larger rendering initiated somewhere up the component
-   * tree.  In that case, it needs to cancel the previous rendering and
-   * remap itself as a part of the current parent rendering.
-   */
-  _remapFiber(oldFiber: Fiber) {
-    oldFiber.cancel();
-    this.shouldPatch = oldFiber.shouldPatch;
-    if (oldFiber === oldFiber.root) {
-      oldFiber.counter++;
-    }
-    if (oldFiber.parent && !this.parent) {
-      // re-map links
-      this.parent = oldFiber.parent;
-      this.root = this.parent.root;
-      this.sibling = oldFiber.sibling;
-      if (this.parent.lastChild === oldFiber) {
-        this.parent.lastChild = this;
-      }
-      if (this.parent.child === oldFiber) {
-        this.parent.child = this;
-      } else {
-        let current = this.parent.child!;
-        while (true) {
-          if (current.sibling === oldFiber) {
-            current.sibling = this;
-            break;
-          }
-          current = current.sibling!;
-        }
-      }
-    }
-  }
-
-  /**
-   * This function has been taken from
-   * https://medium.com/react-in-depth/the-how-and-why-on-reacts-usage-of-linked-list-in-fiber-67f1014d0eb7
-   */
-  _walk(doWork: (f: Fiber) => Fiber | null) {
-    let root = this;
-    let current: Fiber = this;
-    while (true) {
-      const child = doWork(current);
-      if (child) {
-        current = child;
-        continue;
-      }
-      if (current === root) {
-        return;
-      }
-      while (!current.sibling) {
-        if (!current.parent || current.parent === root) {
-          return;
-        }
-        current = current.parent;
-      }
-      current = current.sibling;
-    }
-  }
-
-  /**
-   * Successfully complete the work of the fiber: call the mount or patch hooks
-   * and patch the DOM. This function is called once the fiber and its children
-   * are ready, and the scheduler decides to process it.
-   */
-  complete() {
-    let component = this.component;
-    this.isCompleted = true;
-    if (!this.inserter && !component.__owl__.isMounted) {
-      return;
-    }
-
-    // build patchQueue
-    const patchQueue: Fiber[] = [];
-    const doWork: (Fiber) => Fiber | null = function(f) {
-      patchQueue.push(f);
-      return f.child;
-    };
-    this._walk(doWork);
-    const patchLen = patchQueue.length;
-
-    // call willPatch hook on each fiber of patchQueue
-    for (let i = 0; i < patchLen; i++) {
-      const fiber = patchQueue[i];
-      if (fiber.shouldPatch) {
-        component = fiber.component;
-        if (component.__owl__.willPatchCB) {
-          component.__owl__.willPatchCB();
-        }
-        component.willPatch();
-      }
-    }
-
-    // call __patch on each fiber of (reversed) patchQueue
-    for (let i = patchLen - 1; i >= 0; i--) {
-      const fiber = patchQueue[i];
-      component = fiber.component;
-      component.__patch(fiber.vnode!);
-      if (!fiber.shouldPatch && (!fiber.inserter || i !== 0)) {
-        component.__owl__.pvnode!.elm = component.__owl__.vnode!.elm;
-      }
-      component.__owl__.currentFiber = null;
-    }
-
-    // insert into the DOM (mount case)
-    let inDOM = false;
-    if (this.inserter) {
-      this.inserter(this.component.el!);
-      inDOM = document.body.contains(this.component.el);
-      this.component.env.qweb.trigger("dom-appended");
-    }
-
-    // call patched/mounted hook on each fiber of (reversed) patchQueue
-    for (let i = patchLen - 1; i >= 0; i--) {
-      const fiber = patchQueue[i];
-      component = fiber.component;
-      if (fiber.shouldPatch && !this.inserter) {
-        component.patched();
-        if (component.__owl__.patchedCB) {
-          component.__owl__.patchedCB();
-        }
-      } else if (this.inserter ? inDOM : true) {
-        component.__callMounted();
-      }
-    }
-  }
-
-  /**
-   * Cancel a fiber and all its children.
-   */
-  cancel() {
-    this._walk(f => {
-      if (!f.isRendered) {
-        f.root.counter--;
-      }
-      f.isCompleted = true;
-      return f.child;
-    });
-  }
-
-  /**
-   * This is the global error handler for errors occurring in Owl main lifecycle
-   * methods.  Caught errors are triggered on the QWeb instance, and are
-   * potentially given to some parent component which implements `catchError`.
-   *
-   * If there are no such component, we destroy everything. This is better than
-   * being in a corrupted state.
-   */
-  handleError(error: Error) {
-    let component = this.component;
-    this.vnode = component.__owl__.vnode || h("div");
-
-    const qweb = component.env.qweb;
-    let root = component;
-    let canCatch = false;
-    while (component && !(canCatch = !!component.catchError)) {
-      root = component;
-      component = component.__owl__.parent!;
-    }
-    qweb.trigger("error", error);
-
-    if (canCatch) {
-      component.catchError!(error);
-    } else {
-      // the 3 next lines aim to mark the root fiber as being in error, and
-      // to force it to end, without waiting for its children
-      this.root.counter = 0;
-      this.root.error = error;
-      scheduler.flush();
-      root.destroy();
-    }
-  }
-}
@@ -21,7 +21,7 @@ QWeb.utils.validateProps = function(Widget, props: Object) {
        // optional prop
        break;
      }
-      if (!(propName in props)) {
+      if (!props[propName]) {
        throw new Error(`Missing props '${propsDef[i]}' (component '${Widget.name}')`);
      }
    }
@@ -40,15 +40,9 @@ QWeb.utils.validateProps = function(Widget, props: Object) {
          break;
        }
      }
-      let isValid;
-      try {
-        isValid = isValidProp(props[propName], propsDef[propName]);
-      } catch (e) {
-        e.message = `Invalid prop '${propName}' in component ${Widget.name} (${e.message})`;
-        throw e;
-      }
+      let isValid = isValidProp(props[propName], propsDef[propName]);
      if (!isValid) {
-        throw new Error(`Invalid Prop '${propName}' in component '${Widget.name}'`);
+        throw new Error(`Props '${propName}' of invalid type in component '${Widget.name}'`);
      }
    }
    for (let propName in props) {
@@ -86,30 +80,17 @@ function isValidProp(prop, propDef): boolean {
    return result;
  }
  // propsDef is an object
-  if (propDef.optional && prop === undefined) {
-    return true;
-  }
-  let result = propDef.type ? isValidProp(prop, propDef.type) : true;
-  if (propDef.validate) {
-    result = result && propDef.validate(prop);
-  }
-  if (propDef.type === Array && propDef.element) {
+  let result = isValidProp(prop, propDef.type);
+  if (propDef.type === Array) {
    for (let i = 0, iLen = prop.length; i < iLen; i++) {
      result = result && isValidProp(prop[i], propDef.element);
    }
  }
-  if (propDef.type === Object && propDef.shape) {
+  if (propDef.type === Object) {
    const shape = propDef.shape;
    for (let key in shape) {
      result = result && isValidProp(prop[key], shape[key]);
    }
-    if (result) {
-      for (let propName in prop) {
-        if (!(propName in shape)) {
-          throw new Error(`unknown prop '${propName}'`);
-        }
-      }
-    }
  }
  return result;
 }
@@ -1,102 +0,0 @@
-import { Fiber } from "./fiber";
-
-/**
- * Owl Scheduler Class
- *
- * The scheduler is the part of Owl that will effectively apply a rendering
- * whenever a fiber is ready.
- *
- * Briefly, it can be used to register root fibers.  Whenever there is an
- * active root fiber, it will poll continuously each animation frame (so, about
- * once every 16ms) and whenever a root fiber is ready, it will apply it.
- */
-
-interface Task {
-  fiber: Fiber;
-  callback: (err?: Error) => void;
-}
-
-export class Scheduler {
-  tasks: Task[] = [];
-  isRunning: boolean = false;
-  requestAnimationFrame: typeof window.requestAnimationFrame;
-
-  constructor(requestAnimationFrame) {
-    this.requestAnimationFrame = requestAnimationFrame;
-  }
-
-  start() {
-    this.isRunning = true;
-    this.scheduleTasks();
-  }
-
-  stop() {
-    this.isRunning = false;
-  }
-
-  addFiber(fiber): Promise<void> {
-    // if the fiber was remapped into a larger rendering fiber, it may not be a
-    // root fiber.  But we only want to register root fibers
-    fiber = fiber.root;
-    return new Promise((resolve, reject) => {
-      if (fiber.error) {
-        return reject(fiber.error);
-      }
-      this.tasks.push({
-        fiber,
-        callback: () => {
-          if (fiber.error) {
-            return reject(fiber.error);
-          }
-          resolve();
-        }
-      });
-      if (!this.isRunning) {
-        this.start();
-      }
-    });
-  }
-
-  /**
-   * Process all current tasks. This only applies to the fibers that are ready.
-   * Other tasks are left unchanged.
-   */
-  flush() {
-    let tasks = this.tasks;
-    this.tasks = [];
-    tasks = tasks.filter(task => {
-      if (task.fiber.isCompleted) {
-        task.callback();
-        return false;
-      }
-      if (task.fiber.counter === 0) {
-        if (!task.fiber.error) {
-          try {
-            task.fiber.complete();
-          } catch (e) {
-            task.fiber.handleError(e);
-          }
-        }
-        task.callback();
-        return false;
-      }
-      return true;
-    });
-    this.tasks = tasks.concat(this.tasks);
-    if (this.tasks.length === 0) {
-      this.stop();
-    }
-  }
-
-  scheduleTasks() {
-    this.requestAnimationFrame(() => {
-      this.flush();
-      if (this.isRunning) {
-        this.scheduleTasks();
-      }
-    });
-  }
-}
-
-const raf = window.requestAnimationFrame.bind(window);
-export const scheduler = new Scheduler(raf);
@@ -1,30 +0,0 @@
-import { QWeb } from "./qweb/index";
-
-/**
- * This file creates and exports the OWL 'config' object, with keys:
- *  - 'mode': 'prod' or 'dev',
- *  - 'env': the environment to use in root components.
- */
-
-interface Config {
-  mode: string;
-}
-
-export const config = {} as Config;
-
-Object.defineProperty(config, "mode", {
-  get() {
-    return QWeb.dev ? "dev" : "prod";
-  },
-  set(mode: string) {
-    QWeb.dev = mode === "dev";
-    if (QWeb.dev) {
-      const url = `https://github.com/odoo/owl/blob/master/doc/reference/config.md#mode`;
-      console.warn(
-        `Owl is running in 'dev' mode.  This is not suitable for production use. See ${url} for more information.`
-      );
-    } else {
-      console.log(`Owl is now running in 'prod' mode.`);
-    }
-  }
-});
@@ -1,148 +0,0 @@
-import { Component } from "./component/component";
-import { scheduler } from "./component/scheduler";
-import { EventBus } from "./core/event_bus";
-import { Observer } from "./core/observer";
-
-/**
- * The `Context` object provides a way to share data between an arbitrary number
- * of component. Usually, data is passed from a parent to its children component,
- * but when we have to deal with some mostly global information, this can be
- * annoying, since each component will need to pass the information to each
- * children, even though some or most of them will not use the information.
- *
- * With a `Context` object, each component can subscribe (with the `useContext`
- * hook) to its state, and will be updated whenever the context state is updated.
- */
-
-function partitionBy<T>(arr: T[], fn: (t: T) => boolean) {
-  let lastGroup: T[] | false = false;
-  let lastValue;
-  return arr.reduce((acc: T[][], cur) => {
-    let curVal = fn(cur);
-    if (lastGroup) {
-      if (curVal === lastValue) {
-        lastGroup.push(cur);
-      } else {
-        lastGroup = false;
-      }
-    }
-    if (!lastGroup) {
-      lastGroup = [cur];
-      acc.push(lastGroup);
-    }
-    lastValue = curVal;
-    return acc;
-  }, []);
-}
-
-export class Context extends EventBus {
-  state: any;
-  observer: Observer;
-  rev: number = 1;
-  // mapping from component id to last observed context id
-  mapping: { [componentId: number]: number } = {};
-
-  constructor(state: Object = {}) {
-    super();
-    this.observer = new Observer();
-    this.observer.notifyCB = () => {
-      // notify components in the next microtask tick to ensure that subscribers
-      // are notified only once for all changes that occur in the same micro tick
-      let rev = this.rev;
-      return Promise.resolve().then(() => {
-        if (rev === this.rev) {
-          this.__notifyComponents();
-        }
-      });
-    };
-    this.state = this.observer.observe(state);
-    this.subscriptions.update = [];
-  }
-
-  /**
-   * Instead of using trigger to emit an update event, we actually implement
-   * our own function to do that.  The reason is that we need to be smarter than
-   * a simple trigger function: we need to wait for parent components to be
-   * done before doing children components.  More precisely, if an update
-   * as an effect of destroying a children, we do not want to call any code
-   * from the child, and certainly not render it.
-   *
-   * This method implements a simple grouping algorithm by depth. If we have
-   * connected components of depths [2, 4,4,4,4, 3,8,8], the Context will notify
-   * them in the following groups: [2], [4,4,4,4], [3], [8,8]. Each group will
-   * be updated sequentially, but each components in a given group will be done in
-   * parallel.
-   *
-   * This is a very simple algorithm, but it avoids checking if a given
-   * component is a child of another.
-   */
-  async __notifyComponents() {
-    const rev = ++this.rev;
-    const subscriptions = this.subscriptions.update;
-    const groups = partitionBy(subscriptions, s => (s.owner ? s.owner.__owl__.depth : -1));
-    for (let group of groups) {
-      const proms = group.map(sub => sub.callback.call(sub.owner, rev));
-      // at this point, each component in the current group has registered a
-      // top level fiber in the scheduler. It could happen that rendering these
-      // components is done (if they have no children).  This is why we manually
-      // flush the scheduler.  This will force the scheduler to check
-      // immediately if they are done, which will cause their rendering
-      // promise to resolve earlier, which means that there is a chance of
-      // processing the next group in the same frame.
-      scheduler.flush();
-      await Promise.all(proms);
-    }
-  }
-}
-
-/**
- * The`useContext` hook is the normal way for a component to register themselve
- * to context state changes. The `useContext` method returns the context state
- */
-export function useContext(ctx: Context): any {
-  const component: Component<any, any> = Component.current!;
-  return useContextWithCB(ctx, component, component.render.bind(component));
-}
-
-export function useContextWithCB(ctx: Context, component: Component<any, any>, method): any {
-  const __owl__ = component.__owl__;
-  const id = __owl__.id;
-  const mapping = ctx.mapping;
-  if (id in mapping) {
-    return ctx.state;
-  }
-  if (!__owl__.observer) {
-    __owl__.observer = new Observer();
-    __owl__.observer.notifyCB = component.render.bind(component);
-  }
-  const currentCB = __owl__.observer.notifyCB;
-  __owl__.observer.notifyCB = function() {
-    if (ctx.rev > mapping[id]) {
-      // in this case, the context has been updated since we were rendering
-      // last, and we do not need to render here with the observer. A
-      // rendering is coming anyway, with the correct props.
-      return;
-    }
-    currentCB();
-  };
-
-  mapping[id] = 0;
-  const renderFn = __owl__.renderFn;
-  __owl__.renderFn = function(comp, params) {
-    mapping[id] = ctx.rev;
-    return renderFn(comp, params);
-  };
-  ctx.on("update", component, async contextRev => {
-    if (mapping[id] < contextRev) {
-      mapping[id] = contextRev;
-      await method();
-    }
-  });
-  const __destroy = component.__destroy;
-  component.__destroy = parent => {
-    ctx.off("update", component);
-    delete mapping[id];
-    __destroy.call(component, parent);
-  };
-  return ctx.state;
-}
@@ -20,9 +20,18 @@
 export class Observer {
  rev: number = 1;
  allowMutations: boolean = true;
+  dirty: boolean = false;
  weakMap: WeakMap<any, any> = new WeakMap();

  notifyCB() {}
+  async notifyChange() {
+    this.dirty = true;
+    await Promise.resolve();
+    if (this.dirty) {
+      this.dirty = false;
+      this.notifyCB();
+    }
+  }

  observe<T>(value: T, parent?: any): T {
    if (value === null || typeof value !== "object" || value instanceof Date) {
@@ -37,6 +46,10 @@ export class Observer {
    const metadata = this.weakMap.get(value);
    return metadata ? metadata.rev : 0;
  }
+  deepRevNumber(value): number {
+    const metadata = this.weakMap.get(value);
+    return metadata ? metadata.deepRev : 0;
+  }

  _observe(value, parent) {
    var self = this;
@@ -56,7 +69,7 @@ export class Observer {
          }
          self._updateRevNumber(target);
          target[key] = newVal;
-          self.notifyCB();
+          self.notifyChange();
        }
        return true;
      },
@@ -64,7 +77,7 @@ export class Observer {
        if (key in target) {
          delete target[key];
          self._updateRevNumber(target);
-          self.notifyCB();
+          self.notifyChange();
        }
        return true;
      }
@@ -74,6 +87,7 @@ export class Observer {
      value,
      proxy,
      rev: this.rev,
+      deepRev: this.rev,
      parent
    };

@@ -85,10 +99,11 @@ export class Observer {
  _updateRevNumber(target: any) {
    this.rev++;
    let metadata = this.weakMap.get(target);
+    metadata.rev!++;
    let parent = target;
    do {
      metadata = this.weakMap.get(parent);
-      metadata.rev++;
+      metadata.deepRev++;
    } while ((parent = metadata.parent) && parent !== target);
  }
 }
@@ -1,15 +0,0 @@
-import { Component } from "../component/component";
-
-/**
- * We define here OwlEvent, a subclass of CustomEvent, with an additional
- * attribute:
- *  - originalComponent: the component that triggered the event
- */
-
-export class OwlEvent<T> extends CustomEvent<T> {
-  originalComponent: Component<any, any>;
-  constructor(component, eventType, options) {
-    super(eventType, options);
-    this.originalComponent = component;
-  }
-}
@@ -22,7 +22,7 @@ import { Observer } from "./core/observer";
 * trigger a rerendering of the current component.
 */
 export function useState<T>(state: T): T {
-  const component: Component<any, any> = Component.current!;
+  const component: Component<any, any> = Component._current;
  const __owl__ = component.__owl__;
  if (!__owl__.observer) {
    __owl__.observer = new Observer();
@@ -35,43 +35,21 @@ export function useState<T>(state: T): T {
 // Life cycle hooks
 // -----------------------------------------------------------------------------
 function makeLifecycleHook(method: string, reverse: boolean = false) {
-  if (reverse) {
-    return function(cb) {
-      const component: Component<any, any> = Component.current!;
-      if (component.__owl__[method]) {
-        const current = component.__owl__[method];
-        component.__owl__[method] = function() {
-          current.call(component);
-          cb.call(component);
-        };
-      } else {
-        component.__owl__[method] = cb;
-      }
-    };
-  } else {
-    return function(cb) {
-      const component: Component<any, any> = Component.current!;
-      if (component.__owl__[method]) {
-        const current = component.__owl__[method];
-        component.__owl__[method] = function() {
-          cb.call(component);
-          current.call(component);
-        };
-      } else {
-        component.__owl__[method] = cb;
-      }
-    };
-  }
-}
-
-function makeAsyncHook(method: string) {
  return function(cb) {
-    const component: Component<any, any> = Component.current!;
+    const component: Component<any, any> = Component._current;
    if (component.__owl__[method]) {
      const current = component.__owl__[method];
-      component.__owl__[method] = function(...args) {
-        return Promise.all[(current.call(component, ...args), cb.call(component, ...args))];
-      };
+      if (reverse) {
+        component.__owl__[method] = function() {
+          current.call(component);
+          cb.call(component);
+        };
+      } else {
+        component.__owl__[method] = function() {
+          cb.call(component);
+          current.call(component);
+        };
+      }
    } else {
      component.__owl__[method] = cb;
    }
@@ -83,9 +61,6 @@ export const onWillUnmount = makeLifecycleHook("willUnmountCB");
 export const onWillPatch = makeLifecycleHook("willPatchCB");
 export const onPatched = makeLifecycleHook("patchedCB", true);

-export const onWillStart = makeAsyncHook("willStartCB");
-export const onWillUpdateProps = makeAsyncHook("willUpdatePropsCB");
-
 // -----------------------------------------------------------------------------
 // useRef
 // -----------------------------------------------------------------------------
@@ -100,16 +75,11 @@ interface Ref {
 }

 export function useRef(name: string): Ref {
-  const __owl__ = Component.current!.__owl__;
+  const __owl__ = Component._current.__owl__;
  return {
    get el(): HTMLElement | null {
      const val = __owl__.refs && __owl__.refs[name];
-      if (val instanceof HTMLElement) {
-        return val;
-      } else if (val instanceof Component) {
-        return val.el;
-      }
-      return null;
+      return val instanceof HTMLElement ? val : null;
    },
    get comp(): Component<any, any> | null {
      const val = __owl__.refs && __owl__.refs[name];
@@ -122,12 +92,13 @@ export function useRef(name: string): Ref {
 // useSubEnv
 // -----------------------------------------------------------------------------

+
 /**
 * This hook is a simple way to let components use a sub environment.  Note that
 * like for all hooks, it is important that this is only called in the
 * constructor method.
 */
 export function useSubEnv(nextEnv) {
-  const component = Component.current!;
+  const component = Component._current;
  component.env = Object.assign(Object.create(component.env), nextEnv);
-}
+}
@@ -7,34 +7,40 @@
 import { EventBus } from "./core/event_bus";
 import { Observer } from "./core/observer";
 import { QWeb } from "./qweb/index";
-import { config } from "./config";
-import * as _store from "./store";
+import { ConnectedComponent } from "./store/connected_component";
+import { Store } from "./store/store";
 import * as _utils from "./utils";
 import * as _tags from "./tags";
-import { AsyncRoot } from "./misc/async_root";
-import { Portal } from "./misc/portal";
 import * as _hooks from "./hooks";
-import * as _context from "./context";
-import { Link } from "./router/link";
-import { RouteComponent } from "./router/route_component";
-import { Router } from "./router/router";
+import { Link } from "./router/Link";
+import { RouteComponent } from "./router/RouteComponent";
+import { Router } from "./router/Router";

 export { Component } from "./component/component";
 export { QWeb };
-export { config };

-export const Context = _context.Context;
 export const useState = _hooks.useState;
 export const core = { EventBus, Observer };
 export const router = { Router, RouteComponent, Link };
-export const Store = _store.Store;
+export const store = { Store, ConnectedComponent };
 export const utils = _utils;
 export const tags = _tags;
-export const misc = { AsyncRoot, Portal };
-export const hooks = Object.assign({}, _hooks, {
-  useContext: _context.useContext,
-  useDispatch: _store.useDispatch,
-  useGetters: _store.useGetters,
-  useStore: _store.useStore
-});
+export const hooks = _hooks;
 export const __info__ = {};
+
+Object.defineProperty(__info__, "mode", {
+  get() {
+    return QWeb.dev ? "dev" : "prod";
+  },
+  set(mode: string) {
+    QWeb.dev = mode === "dev";
+    if (QWeb.dev) {
+      const url = `https://github.com/odoo/owl/blob/master/doc/tooling.md#development-mode`;
+      console.warn(
+        `Owl is running in 'dev' mode.  This is not suitable for production use. See ${url} for more information.`
+      );
+    } else {
+      console.log(`Owl is now running in 'prod' mode.`);
+    }
+  }
+});
@@ -1,19 +0,0 @@
-import { Component } from "../component/component";
-import { xml } from "../tags";
-
-/**
- * AsyncRoot
- *
- * Owl is by default asynchronous, and the user interface will wait for all its
- * subcomponents to be rendered before updating the DOM. This is most of the
- * time what we want, but in some cases, it makes sense to "detach" a component
- * from this coordination.  This is the goal of the AsyncRoot component.
- */
-
-export class AsyncRoot extends Component<any, any> {
-  static template = xml`<t t-slot="default"/>`;
-
-  async __updateProps(nextProps, parentFiber) {
-    this.render(parentFiber.force);
-  }
-}
@@ -1,167 +0,0 @@
-import { Component, portalSymbol } from "../component/component";
-import { VNode, patch } from "../vdom/index";
-import { xml } from "../tags";
-import { OwlEvent } from "../core/owl_event";
-import { useSubEnv } from "../hooks";
-
-/**
- * Portal
- *
- * The Portal component allows to render a part of a component outside it's DOM.
- * It is for example useful for dialogs: for css reasons, dialogs are in general
- * placed in a specific spot of the DOM (e.g. directly in the body). With the
- * Portal, a component can conditionally specify in its tempate that it contains
- * a dialog, and where this dialog should be inserted in the DOM.
- *
- * The Portal component ensures that the communication between the content of
- * the Portal and its parent properly works: business events reaching the Portal
- * are re-triggered on an empty <portal> node located in the parent's DOM.
- */
-
-export class Portal extends Component<any, any> {
-  static template = xml`<portal><t t-slot="default"/></portal>`;
-  static props = {
-    target: {
-      type: String
-    }
-  };
-
-  // boolean to indicate whether or not we must listen to 'dom-appended' event
-  // to hook on the moment when the target is inserted into the DOM (because it
-  // is not when the portal is rendered)
-  doTargetLookUp: boolean = true;
-  // set of encountered events that need to be redirected
-  _handledEvents: Set<string> = new Set();
-  // function that will be the event's tunnel (needs to be an arrow function to
-  // avoid having to rebind `this`)
-  _handlerTunnel: (f: OwlEvent<any>) => void = (ev: OwlEvent<any>) => {
-    ev.stopPropagation();
-    this.__trigger(ev.originalComponent, ev.type, ev.detail);
-  };
-  // Storing the parent's env
-  parentEnv: any = null;
-  // represents the element that is moved somewhere else
-  portal: VNode | null = null;
-  // the target where we will move `portal`
-  target: HTMLElement | null = null;
-
-  constructor(parent, props) {
-    super(parent, props);
-    this.parentEnv = parent ? parent.env : {};
-    // put a callback in the env that is propagated to children s.t. portal can
-    // register an handler to those events just before children will trigger them
-    useSubEnv({
-      [portalSymbol]: ev => {
-        if (!this._handledEvents.has(ev.type)) {
-          this.portal!.elm!.addEventListener(ev.type, this._handlerTunnel);
-          this._handledEvents.add(ev.type);
-        }
-      }
-    });
-  }
-  /**
-   * Override to revert back to a classic Component's structure
-   *
-   * @override
-   */
-  __callWillUnmount() {
-    super.__callWillUnmount();
-    this.el!.appendChild(this.portal!.elm!);
-    this.doTargetLookUp = true;
-  }
-  /**
-   * At each DOM change, we must ensure that the portal contains exactly one
-   * child
-   */
-  __checkVNodeStructure(vnode: VNode) {
-    const children = vnode.children!;
-    let countRealNodes = 0;
-    for (let child of children) {
-      if ((child as VNode).sel) {
-        countRealNodes++;
-      }
-    }
-    if (countRealNodes !== 1) {
-      throw new Error(`Portal must have exactly one non-text child (has ${countRealNodes})`);
-    }
-  }
-  /**
-   * Ensure the target is still there at whichever time we render
-   */
-  __checkTargetPresence() {
-    if (!this.target || !document.contains(this.target)) {
-      throw new Error(`Could not find any match for "${this.props.target}"`);
-    }
-  }
-  /**
-   * Move the portal's element to the target
-   */
-  __deployPortal() {
-    this.__checkTargetPresence();
-    this.target!.appendChild(this.portal!.elm!);
-  }
-  /**
-   * Override to remove from the DOM the element we have teleported
-   *
-   * @override
-   */
-  __destroy(parent) {
-    if (this.portal && this.portal.elm) {
-      const displacedElm = this.portal.elm!;
-      const parent = displacedElm.parentNode;
-      if (parent) {
-        parent.removeChild(displacedElm);
-      }
-    }
-    super.__destroy(parent);
-  }
-  /**
-   * Override to patch the element that has been teleported
-   *
-   * @override
-   */
-  __patch(vnode) {
-    if (this.doTargetLookUp) {
-      const target = document.querySelector(this.props.target);
-      if (!target) {
-        this.env.qweb.on("dom-appended", this, () => {
-          this.doTargetLookUp = false;
-          this.env.qweb.off("dom-appended", this);
-          this.target = document.querySelector(this.props.target);
-          this.__deployPortal();
-        });
-      } else {
-        this.doTargetLookUp = false;
-        this.target = target;
-      }
-    }
-    this.__checkVNodeStructure(vnode);
-    const shouldDeploy =
-      (!this.portal || this.el!.contains(this.portal.elm!)) && !this.doTargetLookUp;
-
-    if (!this.doTargetLookUp && !shouldDeploy) {
-      // Only on pure patching, provided the
-      // this.target's parent has not been unmounted
-      this.__checkTargetPresence();
-    }
-
-    const portalPatch = this.portal ? this.portal : document.createElement(vnode.children[0].sel);
-    this.portal = patch(portalPatch, vnode.children![0] as VNode);
-    vnode.children = [];
-
-    super.__patch(vnode);
-
-    if (shouldDeploy) {
-      this.__deployPortal();
-    }
-  }
-  /**
-   * Override to set the env
-   */
-  __trigger(component: Component<any, any>, eventType: string, payload?: any) {
-    const env = this.env;
-    this.env = this.parentEnv;
-    super.__trigger(component, eventType, payload);
-    this.env = env;
-  }
-}
@@ -1,6 +1,6 @@
-import { CompilationContext } from "./compilation_context";
+import { Context } from "./context";
+import { QWebExprVar } from "./expression_parser";
 import { QWeb } from "./qweb";
-import { htmlToVDOM } from "../vdom/html_to_vdom";

 /**
 * Owl QWeb Directives
@@ -19,40 +19,33 @@ import { htmlToVDOM } from "../vdom/html_to_vdom";
 //------------------------------------------------------------------------------
 // t-esc and t-raw
 //------------------------------------------------------------------------------
-QWeb.utils.htmlToVDOM = htmlToVDOM;
+QWeb.utils.getFragment = function(str: string): DocumentFragment {
+  const temp = document.createElement("template");
+  temp.innerHTML = str;
+  return temp.content;
+};

-function compileValueNode(value: any, node: Element, qweb: QWeb, ctx: CompilationContext) {
-  ctx.rootContext.shouldDefineScope = true;
-  if (value === "0") {
-    if (ctx.parentNode) {
-      // the 'zero' magical symbol is where we can find the result of the rendering
-      // of  the body of the t-call.
-      ctx.rootContext.shouldDefineUtils = true;
-      const zeroArgs = ctx.escaping
-        ? `{text: utils.vDomToString(scope[utils.zero])}`
-        : `...scope[utils.zero]`;
-      ctx.addLine(`c${ctx.parentNode}.push(${zeroArgs});`);
-    }
+function compileValueNode(value: any, node: Element, qweb: QWeb, ctx: Context) {
+  if (value === "0" && ctx.caller) {
+    qweb._compileNode(ctx.caller, ctx);
    return;
  }

+  if (value.xml instanceof NodeList) {
+    for (let node of Array.from(value.xml)) {
+      qweb._compileNode(<ChildNode>node, ctx);
+    }
+    return;
+  }
  let exprID: string;
  if (typeof value === "string") {
    exprID = `_${ctx.generateID()}`;
    ctx.addLine(`var ${exprID} = ${ctx.formatExpression(value)};`);
  } else {
-    exprID = `scope.${value.id}`;
+    exprID = value.id;
  }
  ctx.addIf(`${exprID} || ${exprID} === 0`);
-
  if (ctx.escaping) {
-    let protectID;
-    if (value.hasBody) {
-      protectID = ctx.startProtectScope();
-      ctx.addLine(
-        `${exprID} = ${exprID} instanceof utils.VDomArray ? utils.vDomToString(${exprID}) : ${exprID};`
-      );
-    }
    if (ctx.parentTextNode) {
      ctx.addLine(`vn${ctx.parentTextNode}.text += ${exprID};`);
    } else if (ctx.parentNode) {
@@ -62,23 +55,18 @@ function compileValueNode(value: any, node: Element, qweb: QWeb, ctx: Compilatio
      ctx.rootContext.rootNode = nodeID;
      ctx.rootContext.parentTextNode = nodeID;
      ctx.addLine(`var vn${nodeID} = {text: ${exprID}};`);
-      if (ctx.rootContext.shouldDefineResult) {
-        ctx.addLine(`result = vn${nodeID}`);
-      }
-    }
-    if (value.hasBody) {
-      ctx.stopProtectScope(protectID);
+      ctx.addLine(`result = vn${nodeID}`);
    }
  } else {
+    let fragID = ctx.generateID();
    ctx.rootContext.shouldDefineUtils = true;
-    if (value.hasBody) {
-      ctx.addLine(
-        `const vnodeArray = ${exprID} instanceof utils.VDomArray ? ${exprID} : utils.htmlToVDOM(${exprID});`
-      );
-      ctx.addLine(`c${ctx.parentNode}.push(...vnodeArray);`);
-    } else {
-      ctx.addLine(`c${ctx.parentNode}.push(...utils.htmlToVDOM(${exprID}));`);
-    }
+    ctx.addLine(`var frag${fragID} = utils.getFragment(${exprID})`);
+    let tempNodeID = ctx.generateID();
+    ctx.addLine(`var p${tempNodeID} = {hook: {`);
+    ctx.addLine(`  insert: n => n.elm.parentNode.replaceChild(frag${fragID}, n.elm),`);
+    ctx.addLine(`}};`);
+    ctx.addLine(`var vn${tempNodeID} = h('div', p${tempNodeID})`);
+    ctx.addLine(`c${ctx.parentNode}.push(vn${tempNodeID});`);
  }
  if (node.childNodes.length) {
    ctx.addElse();
@@ -92,6 +80,11 @@ QWeb.addDirective({
  name: "esc",
  priority: 70,
  atNodeEncounter({ node, qweb, ctx }): boolean {
+    if (node.nodeName !== "t") {
+      let nodeID = qweb._compileGenericNode(node, ctx);
+      ctx = ctx.withParent(nodeID);
+      ctx = ctx.subContext("currentKey", ctx.lastNodeKey);
+    }
    let value = ctx.getValue(node.getAttribute("t-esc")!);
    compileValueNode(value, node, qweb, ctx.subContext("escaping", true));
    return true;
@@ -102,6 +95,11 @@ QWeb.addDirective({
  name: "raw",
  priority: 80,
  atNodeEncounter({ node, qweb, ctx }): boolean {
+    if (node.nodeName !== "t") {
+      let nodeID = qweb._compileGenericNode(node, ctx);
+      ctx = ctx.withParent(nodeID);
+      ctx = ctx.subContext("currentKey", ctx.lastNodeKey);
+    }
    let value = ctx.getValue(node.getAttribute("t-raw")!);
    compileValueNode(value, node, qweb, ctx);
    return true;
@@ -115,46 +113,25 @@ QWeb.addDirective({
  name: "set",
  extraNames: ["value"],
  priority: 60,
-  atNodeEncounter({ node, qweb, ctx }): boolean {
-    ctx.rootContext.shouldDefineScope = true;
+  atNodeEncounter({ node, ctx }): boolean {
    const variable = node.getAttribute("t-set")!;
    let value = node.getAttribute("t-value")!;
-    ctx.variables[variable] = ctx.variables[variable] || {};
-    let qwebvar = ctx.variables[variable];
-    const hasBody = node.hasChildNodes();
-
-    qwebvar.id = variable;
-    qwebvar.expr = `scope.${variable}`;
    if (value) {
      const formattedValue = ctx.formatExpression(value);
-      ctx.addLine(`${qwebvar.expr} = ${formattedValue};`);
-      qwebvar.value = formattedValue;
-    }
-
-    if (hasBody) {
-      ctx.rootContext.shouldDefineUtils = true;
-      if (value) {
-        ctx.addIf(`!(${qwebvar.expr})`);
-      }
-      const tempParentNodeID = ctx.generateID();
-      const _parentNode = ctx.parentNode;
-      ctx.parentNode = tempParentNodeID;
-
-      ctx.addLine(`const c${tempParentNodeID} = new utils.VDomArray();`);
-      const nodeCopy = node.cloneNode(true) as Element;
-      for (let attr of ["t-set", "t-value", "t-if", "t-else", "t-elif"]) {
-        nodeCopy.removeAttribute(attr);
-      }
-      qweb._compileNode(nodeCopy, ctx);
-
-      ctx.addLine(`${qwebvar.expr} = c${tempParentNodeID}`);
-      qwebvar.value = `c${tempParentNodeID}`;
-      qwebvar.hasBody = true;
-
-      ctx.parentNode = _parentNode;
-      if (value) {
-        ctx.closeIf();
+      if (ctx.variables.hasOwnProperty(variable)) {
+        ctx.addLine(`${(<QWebExprVar>ctx.variables[variable]).id} = ${formattedValue}`);
+      } else {
+        const varName = `_${ctx.generateID()}`;
+        ctx.addLine(`var ${varName} = ${formattedValue};`);
+        ctx.variables[variable] = {
+          id: varName,
+          expr: formattedValue
+        };
      }
+    } else {
+      ctx.variables[variable] = {
+        xml: node.childNodes
+      };
    }
    return true;
  }
@@ -168,7 +145,7 @@ QWeb.addDirective({
  priority: 20,
  atNodeEncounter({ node, ctx }): boolean {
    let cond = ctx.getValue(node.getAttribute("t-if")!);
-    ctx.addIf(typeof cond === "string" ? ctx.formatExpression(cond) : `scope.${cond.id!}`);
+    ctx.addIf(`${ctx.formatExpression(cond)}`);
    return false;
  },
  finalize({ ctx }) {
@@ -181,9 +158,7 @@ QWeb.addDirective({
  priority: 30,
  atNodeEncounter({ node, ctx }): boolean {
    let cond = ctx.getValue(node.getAttribute("t-elif")!);
-    ctx.addLine(
-      `else if (${typeof cond === "string" ? ctx.formatExpression(cond) : `scope.${cond.id}`}) {`
-    );
+    ctx.addLine(`else if (${ctx.formatExpression(cond)}) {`);
    ctx.indent();
    return false;
  },
@@ -212,9 +187,6 @@ QWeb.addDirective({
  name: "call",
  priority: 50,
  atNodeEncounter({ node, qweb, ctx }): boolean {
-    // Step 1: sanity checks
-    // ------------------------------------------------
-    ctx.rootContext.shouldDefineScope = true;
    if (node.nodeName !== "t") {
      throw new Error("Invalid tag for t-call directive (should be 't')");
    }
@@ -223,63 +195,83 @@ QWeb.addDirective({
    if (!nodeTemplate) {
      throw new Error(`Cannot find template "${subTemplate}" (t-call)`);
    }
+    const nodeCopy = node.cloneNode(true) as Element;
+    nodeCopy.removeAttribute("t-call");

-    // Step 2: compile target template in sub templates
-    // ------------------------------------------------
-    if (!qweb.subTemplates[subTemplate]) {
-      qweb.subTemplates[subTemplate] = true;
-      const subTemplateFn = qweb._compile(subTemplate, nodeTemplate.elem, ctx);
-      qweb.subTemplates[subTemplate] = subTemplateFn;
-    }
+    // extract variables from nodecopy
+    const tempCtx = new Context();
+    tempCtx.nextID = ctx.rootContext.nextID;
+    tempCtx.allowMultipleRoots = true;
+    qweb._compileNode(nodeCopy, tempCtx);
+    const vars = Object.assign({}, ctx.variables, tempCtx.variables);
+    ctx.rootContext.nextID = tempCtx.nextID;

-    // Step 3: compile t-call body if necessary
-    // ------------------------------------------------
-    let hasBody = node.hasChildNodes();
-    let protectID;
-    if (hasBody) {
-      // we add a sub scope to protect the ambient scope
-      ctx.addLine(`{`);
-      ctx.indent();
-      protectID = ctx.startProtectScope();
-      const nodeCopy = node.cloneNode(true) as Element;
-      nodeCopy.removeAttribute("t-call");
-      const parentNode = ctx.parentNode;
-      ctx.parentNode = "__0";
-      // this local scope is intended to trap c__0
-      ctx.addLine(`{`);
-      ctx.indent();
-      ctx.addLine("let c__0 = [];");
-      qweb._compileNode(nodeCopy, ctx);
-      ctx.rootContext.shouldDefineUtils = true;
-      ctx.addLine("scope[utils.zero] = c__0;");
-      ctx.parentNode = parentNode;
-      ctx.dedent();
-      ctx.addLine(`}`);
-    }
+    const templateMap = Object.create(ctx.templates);
+    // open new scope, if necessary
+    const hasNewVariables = Object.keys(tempCtx.variables).length > 0;

-    // Step 4: add the appropriate function call to current component
-    // ------------------------------------------------
-    const callingScope = hasBody ? "scope" : "Object.assign(Object.create(context), scope)";
-    if (ctx.parentNode) {
+    // compile sub template
+    let subCtx = ctx.subContext("caller", nodeCopy).subContext("variables", Object.create(vars));
+    subCtx = subCtx.subContext("templates", templateMap);
+
+    if (templateMap[subTemplate]) {
+      // OUCH, IT IS A RECURSIVE TEMPLATE SITUATION...
+      // This is a tricky situation... We obviously cannot inline the compiled
+      // template. So, what we need to do is to compile it, and make sure we
+      // properly transfer everything from the current scope to the sub template.
+      ctx.rootContext.shouldTrackScope = true;
+      ctx.rootContext.shouldDefineOwner = true;
+      let subTemplateName;
+      if (ctx.hasParentWidget) {
+        subTemplateName = ctx.templateName;
+      } else {
+        subTemplateName = `__${ctx.generateID()}`;
+        subCtx.variables = {};
+        let id = 0;
+        for (let v in vars) {
+          subCtx.variables[v] = vars[v];
+          (vars[v] as any).id = `_v${id++}`;
+        }
+        const subTemplateFn = qweb._compile(subTemplateName, nodeTemplate.elem, subCtx);
+        qweb.recursiveFns[subTemplateName] = subTemplateFn;
+      }
+      let varCode = `{}`;
+      if (Object.keys(vars).length) {
+        let id = 0;
+        const content = Object.values(vars)
+          .map((v: any) => `_v${id++}: ${v.expr}`)
+          .join(",");
+        varCode = `{${content}}`;
+      }
      ctx.addLine(
-        `this.subTemplates['${subTemplate}'].call(this, ${callingScope}, Object.assign({}, extra, {parentNode: c${ctx.parentNode}}));`
+        `this.recursiveFns['${subTemplateName}'].call(this, context, Object.assign({}, extra, {parentNode: c${ctx.parentNode}, fiber: {vars: ${varCode}, scope}}));`
      );
-    } else {
-      // this is a t-call with no parentnode, we need to extract the result
-      ctx.rootContext.shouldDefineResult = true;
-      ctx.addLine(`result = []`);
-      ctx.addLine(
-        `this.subTemplates['${subTemplate}'].call(this, ${callingScope}, Object.assign({}, extra, {parentNode: result}));`
-      );
-      ctx.addLine(`result = result[0]`);
+      return true;
+    }
+    templateMap[subTemplate] = true;
+
+    if (hasNewVariables) {
+      ctx.addLine("{");
+      ctx.indent();
+      // add new variables, if any
+      for (let key in tempCtx.variables) {
+        const v = tempCtx.variables[key];
+        if ((<QWebExprVar>v).expr) {
+          ctx.addLine(`let ${(<QWebExprVar>v).id} = ${(<QWebExprVar>v).expr};`);
+        }
+        // todo: handle XML variables...
+      }
+    }
+    qweb._compileNode(nodeTemplate.elem, subCtx);
+
+    // close new scope
+    if (hasNewVariables) {
+      ctx.dedent();
+      ctx.addLine("}");
    }

-    // Step 5: restore previous scope
-    // ------------------------------------------------
-    if (hasBody) {
-      ctx.stopProtectScope(protectID);
-      ctx.dedent();
-      ctx.addLine(`}`);
+    if (node.hasAttribute("t-if") || node.hasAttribute("t-else") || node.hasAttribute("t-elif")) {
+      ctx.closeIf();
    }

    return true;
@@ -294,8 +286,8 @@ QWeb.addDirective({
  extraNames: ["as"],
  priority: 10,
  atNodeEncounter({ node, qweb, ctx }): boolean {
-    ctx.rootContext.shouldDefineScope = true;
-    ctx = ctx.subContext("loopNumber", ctx.loopNumber + 1);
+    ctx.rootContext.shouldProtectContext = true;
+    ctx = ctx.subContext("inLoop", true);
    const elems = node.getAttribute("t-foreach")!;
    const name = node.getAttribute("t-as")!;
    let arrayID = ctx.generateID();
@@ -309,33 +301,37 @@ QWeb.addDirective({
    ctx.addLine(`_${valuesID} = Object.values(_${arrayID});`);
    ctx.closeIf();
    ctx.addLine(`var _length${keysID} = _${keysID}.length;`);
-    let varsID = ctx.startProtectScope();
-    const loopVar = `i${ctx.loopNumber}`;
-    ctx.addLine(`for (let ${loopVar} = 0; ${loopVar} < _length${keysID}; ${loopVar}++) {`);
+    ctx.addLine(`for (let i = 0; i < _length${keysID}; i++) {`);
    ctx.indent();
-
-    ctx.addLine(`scope.${name}_first = ${loopVar} === 0`);
-    ctx.addLine(`scope.${name}_last = ${loopVar} === _length${keysID} - 1`);
-    ctx.addLine(`scope.${name}_index = ${loopVar}`);
-    ctx.addLine(`scope.${name} = _${keysID}[${loopVar}]`);
-    ctx.addLine(`scope.${name}_value = _${valuesID}[${loopVar}]`);
+    ctx.addToScope(name + "_first", "i === 0");
+    ctx.addToScope(name + "_last", `i === _length${keysID} - 1`);
+    ctx.addToScope(name + "_index", "i");
+    ctx.addToScope(name, `_${keysID}[i]`);
+    ctx.addToScope(name + "_value", `_${valuesID}[i]`);
    const nodeCopy = <Element>node.cloneNode(true);
-    let shouldWarn =
-      !nodeCopy.hasAttribute("t-key") &&
-      node.children.length === 1 &&
-      node.children[0].tagName !== "t" &&
-      !node.children[0].hasAttribute("t-key");
+    let shouldWarn = nodeCopy.tagName !== "t" && !nodeCopy.hasAttribute("t-key");
+    if (!shouldWarn && node.tagName === "t") {
+      if (node.hasAttribute("t-component") && !node.hasAttribute("t-key")) {
+        shouldWarn = true;
+      }
+      if (
+        !shouldWarn &&
+        node.children.length === 1 &&
+        node.children[0].tagName !== "t" &&
+        !node.children[0].hasAttribute("t-key")
+      ) {
+        shouldWarn = true;
+      }
+    }
    if (shouldWarn) {
      console.warn(
        `Directive t-foreach should always be used with a t-key! (in template: '${ctx.templateName}')`
      );
    }
-
    nodeCopy.removeAttribute("t-foreach");
    qweb._compileNode(nodeCopy, ctx);
    ctx.dedent();
    ctx.addLine("}");
-    ctx.stopProtectScope(varsID);
    return true;
  }
 });
@@ -5,74 +5,72 @@ export const INTERP_REGEXP = /\{\{.*?\}\}/g;
 // Compilation Context
 //------------------------------------------------------------------------------

-export class CompilationContext {
-  static nextID: number = 1;
+export class Context {
+  nextID: number = 1;
  code: string[] = [];
  variables: { [key: string]: QWebVar } = {};
  escaping: boolean = false;
-  parentNode: number | null | string = null;
+  parentNode: number | null = null;
  parentTextNode: number | null = null;
  rootNode: number | null = null;
  indentLevel: number = 0;
-  rootContext: CompilationContext;
+  rootContext: Context;
+  caller: Element | undefined;
+  shouldDefineOwner: boolean = false;
  shouldDefineParent: boolean = false;
-  shouldDefineScope: boolean = false;
  shouldDefineQWeb: boolean = false;
  shouldDefineUtils: boolean = false;
  shouldDefineRefs: boolean = false;
  shouldDefineResult: boolean = true;
-  loopNumber: number = 0;
+  shouldProtectContext: boolean = false;
+  shouldTrackScope: boolean = false;
+  inLoop: boolean = false;
  inPreTag: boolean = false;
  templateName: string;
  allowMultipleRoots: boolean = false;
  hasParentWidget: boolean = false;
+  scopeVars: any[] = [];
  currentKey: string = "";
+  lastNodeKey: string = ""; // temp variable to communicate to previous caller
+  templates: { [key: string]: boolean } = {};

  constructor(name?: string) {
    this.rootContext = this;
    this.templateName = name || "noname";
+    this.templates[this.templateName] = true;
    this.addLine("var h = this.h;");
  }

  generateID(): number {
-    return CompilationContext.nextID++;
-  }
-
-  /**
-   * This method generates a "template key", which is basically a unique key
-   * which depends on the currently set keys, and on the iteration numbers (if
-   * we are in a loop).
-   *
-   * Such a key is necessary when we need to associate an id to some element
-   * generated by a template (for example, a component)
-   */
-  generateTemplateKey(): string {
-    const id = this.generateID();
-    let locationExpr = `\`__${this.generateID()}__`;
-    for (let i = 0; i < this.loopNumber - 1; i++) {
-      locationExpr += `\${i${i + 1}}__`;
-    }
-    if (this.currentKey) {
-      const k = this.currentKey;
-      this.addLine(`let k${id} = ${locationExpr}\` + ${k};`);
-    } else {
-      locationExpr += this.loopNumber ? `\${i${this.loopNumber}}__\`` : "`";
-      this.addLine(`let k${id} = ${locationExpr};`);
-    }
-    return `k${id}`;
+    const id = this.rootContext.nextID++;
+    return id;
  }

  generateCode(): string[] {
+    const shouldTrackScope = this.shouldTrackScope && this.scopeVars.length;
+    if (shouldTrackScope) {
+      // add some vars to scope if needed
+      for (let scopeVar of this.scopeVars.reverse()) {
+        let { index, key, indent } = scopeVar;
+        const prefix = new Array(indent + 2).join("    ");
+        this.code.splice(index + 1, 0, prefix + `scope.${key} = context.${key};`);
+      }
+      this.code.unshift("    const scope = Object.create(null);");
+    }
+    if (this.shouldProtectContext) {
+      this.code.unshift("    context = Object.create(context);");
+    }
    if (this.shouldDefineResult) {
      this.code.unshift("    let result;");
    }
-
-    if (this.shouldDefineScope) {
-      this.code.unshift("    let scope = Object.create(context);");
-    }
    if (this.shouldDefineRefs) {
      this.code.unshift("    context.__owl__.refs = context.__owl__.refs || {};");
    }
+    if (this.shouldDefineOwner) {
+      // this is necessary to prevent some directives (t-forach for ex) to
+      // pollute the rendering context by adding some keys in it.
+      this.code.unshift("    let owner = context;");
+    }
    if (this.shouldDefineParent) {
      if (this.hasParentWidget) {
        this.code.unshift("    let parent = extra.parent;");
@@ -89,7 +87,7 @@ export class CompilationContext {
    return this.code;
  }

-  withParent(node: number): CompilationContext {
+  withParent(node: number): Context {
    if (
      !this.allowMultipleRoots &&
      this === this.rootContext &&
@@ -100,13 +98,13 @@ export class CompilationContext {
    if (!this.rootContext.rootNode) {
      this.rootContext.rootNode = node;
    }
-    if (!this.parentNode && this.rootContext.shouldDefineResult) {
+    if (!this.parentNode) {
      this.addLine(`result = vn${node};`);
    }
    return this.subContext("parentNode", node);
  }

-  subContext(key: keyof CompilationContext, value: any): CompilationContext {
+  subContext(key: keyof Context, value: any): Context {
    const newContext = Object.create(this);
    newContext[key] = value;
    return newContext;
@@ -126,6 +124,11 @@ export class CompilationContext {
    return this.code.length - 1;
  }

+  addToScope(key: string, expr: string) {
+    const index = this.addLine(`context.${key} = ${expr};`);
+    this.rootContext.scopeVars.push({ index, key, indent: this.indentLevel });
+  }
+
  addIf(condition: string) {
    this.addLine(`if (${condition}) {`);
    this.indent();
@@ -142,7 +145,7 @@ export class CompilationContext {
    this.addLine("}");
  }

-  getValue(val: any): QWebVar | string {
+  getValue(val: any): any {
    return val in this.variables ? this.getValue(this.variables[val]) : val;
  }

@@ -153,7 +156,6 @@ export class CompilationContext {
   * - replace already defined variables by their internal name
   */
  formatExpression(expr: string): string {
-    this.rootContext.shouldDefineScope = true;
    return compileExpr(expr, this.variables);
  }

@@ -174,14 +176,4 @@ export class CompilationContext {
    let r = s.replace(/\{\{.*?\}\}/g, s => "${" + this.formatExpression(s.slice(2, -2)) + "}");
    return "`" + r + "`";
  }
-  startProtectScope(): number {
-    const protectID = this.generateID();
-    this.rootContext.shouldDefineScope = true;
-    this.addLine(`const _origScope${protectID} = scope;`);
-    this.addLine(`scope = Object.assign(Object.create(context), scope);`);
-    return protectID;
-  }
-  stopProtectScope(protectID: number) {
-    this.addLine(`scope = _origScope${protectID};`);
-  }
 }
@@ -25,7 +25,7 @@
 // Misc types, constants and helpers
 //------------------------------------------------------------------------------

-const RESERVED_WORDS = "true,false,NaN,null,undefined,debugger,console,window,in,instanceof,new,function,return,this,eval,void,Math,RegExp,Array,Object,Date".split(
+const RESERVED_WORDS = "true,false,NaN,null,undefined,debugger,console,window,in,instanceof,new,function,return,this,typeof,eval,void,Math,RegExp,Array,Object,Date".split(
  ","
 );

@@ -38,13 +38,17 @@ const WORD_REPLACEMENT = {
  lte: "<="
 };

-export interface QWebVar {
-  id: string; // foo
-  expr: string; // scope.foo (local variables => only foo)
-  value?: string; // 1 + 3
-  hasBody?: boolean;
+export interface QWebExprVar {
+  id: string;
+  expr: string;
 }

+export interface QWebXMLVar {
+  xml: NodeList;
+}
+
+export type QWebVar = QWebExprVar | QWebXMLVar;
+
 //------------------------------------------------------------------------------
 // Tokenizer
 //------------------------------------------------------------------------------
@@ -64,7 +68,6 @@ type TKind =
 interface Token {
  type: TKind;
  value: string;
-  originalValue?: string;
  size?: number;
 }

@@ -79,9 +82,7 @@ const STATIC_TOKEN_MAP: { [key: string]: TKind } = {
  ")": "RIGHT_PAREN"
 };

-// note that the space after typeof is relevant. It makes sure that the formatted
-// expression has a space after typeof
-const OPERATORS = ".,===,==,+,!==,!=,!,||,&&,>=,>,<=,<,?,-,*,/,%,typeof ,=>".split(",");
+const OPERATORS = ".,===,==,+,!==,!=,!,||,&&,>=,>,<=,<,?,-,*,/,%".split(",");

 type Tokenizer = (expr: string) => Token | false;

@@ -164,9 +165,9 @@ const tokenizeOperator: Tokenizer = function(expr) {
 const TOKENIZERS = [
  tokenizeString,
  tokenizeNumber,
-  tokenizeOperator,
  tokenizeSymbol,
-  tokenizeStatic
+  tokenizeStatic,
+  tokenizeOperator
 ];

 /**
@@ -229,53 +230,35 @@ export function tokenize(expr: string): Token[] {
 * - unless the previous token is a dot (in that case, this is a property: `a.b`)
 * - or if the previous token is a left brace or a comma, and the next token is
 *   a colon (in that case, this is an object key: `{a: b}`)
- *
- * Some specific code is also required to support arrow functions. If we detect
- * the arrow operator, then we add the current (or some previous tokens) token to
- * the list of variables so it does not get replaced by a lookup in the context
 */
-export function compileExpr(expr: string, scope: { [key: string]: QWebVar }): string {
-  scope = Object.create(scope);
+export function compileExpr(expr: string, vars: { [key: string]: QWebVar }): string {
  const tokens = tokenize(expr);
+  let result = "";
  for (let i = 0; i < tokens.length; i++) {
    let token = tokens[i];
-    let prevToken = tokens[i - 1];
-    let nextToken = tokens[i + 1];
-    let isVar = token.type === "SYMBOL" && !RESERVED_WORDS.includes(token.value);
    if (token.type === "SYMBOL" && !RESERVED_WORDS.includes(token.value)) {
+      // we need to find if it is a variable
+      let isVar = true;
+      let prevToken = tokens[i - 1];
      if (prevToken) {
        if (prevToken.type === "OPERATOR" && prevToken.value === ".") {
          isVar = false;
        } else if (prevToken.type === "LEFT_BRACE" || prevToken.type === "COMMA") {
+          let nextToken = tokens[i + 1];
          if (nextToken && nextToken.type === "COLON") {
            isVar = false;
          }
        }
      }
-    }
-    if (nextToken && nextToken.type === "OPERATOR" && nextToken.value === "=>") {
-      if (token.type === "RIGHT_PAREN") {
-        let j = i - 1;
-        while (j > 0 && tokens[j].type !== "LEFT_PAREN") {
-          if (tokens[j].type === "SYMBOL" && tokens[j].originalValue) {
-            tokens[j].value = tokens[j].originalValue!;
-            scope[tokens[j].value] = { id: tokens[j].value, expr: tokens[j].value };
-          }
-          j--;
+      if (isVar) {
+        if (token.value in vars && "id" in vars[token.value]) {
+          token.value = (<QWebExprVar>vars[token.value]).id;
+        } else {
+          token.value = `context['${token.value}']`;
        }
-      } else {
-        scope[token.value] = { id: token.value, expr: token.value };
-      }
-    }
-
-    if (isVar) {
-      if (token.value in scope && "id" in scope[token.value]) {
-        token.value = scope[token.value].expr!;
-      } else {
-        token.originalValue = token.value;
-        token.value = `scope['${token.value}']`;
      }
    }
+    result += token.value;
  }
-  return tokens.map(t => t.value).join("");
+  return result;
 }
@@ -30,6 +30,7 @@ QWeb.addDirective({
  name: "on",
  priority: 90,
  atNodeCreation({ ctx, fullName, value, nodeID }) {
+    ctx.rootContext.shouldDefineOwner = true;
    const [eventName, ...mods] = fullName.slice(5).split(".");
    if (!eventName) {
      throw new Error("Missing event name with t-on directive");
@@ -39,34 +40,34 @@ QWeb.addDirective({
      extraArgs = args.slice(1, -1);
      return "";
    });
-    let params = extraArgs ? `context, ${ctx.formatExpression(extraArgs)}` : "context";
-    let handler = `function (e) {if (!context.__owl__.isMounted){return}`;
-    handler += mods
-      .map(function(mod) {
-        return MODS_CODE[mod];
-      })
-      .join("");
-    if (handlerName) {
-      if (!extraArgs) {
-        handler += `const fn = context['${handlerName}'];`;
-        handler += `if (fn) { fn.call(${params}, e); } else { context.${handlerName}; }`;
-        handler += `}`;
-        ctx.addLine(
-          `extra.handlers['${eventName}' + ${nodeID}] = extra.handlers['${eventName}' + ${nodeID}] || ${handler};`
-        );
-        ctx.addLine(`p${nodeID}.on['${eventName}'] = extra.handlers['${eventName}' + ${nodeID}];`);
-      } else {
-        const handlerKey = `handler${ctx.generateID()}`;
-        ctx.addLine(
-          `const ${handlerKey} = context['${handlerName}'] && context['${handlerName}'].bind(${params});`
-        );
-        handler += `if (${handlerKey}) { ${handlerKey}(e); } else { context.${value}; }`;
-        handler += `}`;
-        ctx.addLine(`p${nodeID}.on['${eventName}'] = ${handler};`);
-      }
+    ctx.addIf(`!context['${handlerName}']`);
+    ctx.addLine(
+      `throw new Error('Missing handler \\'' + '${handlerName}' + \`\\' when evaluating template '${ctx.templateName.replace(
+        /`/g,
+        "'"
+      )}'\`)`
+    );
+    ctx.closeIf();
+    let params = extraArgs ? `owner, ${ctx.formatExpression(extraArgs)}` : "owner";
+    let handler;
+    if (mods.length > 0) {
+      handler = `function (e) {`;
+      handler += mods
+        .map(function(mod) {
+          return MODS_CODE[mod];
+        })
+        .join("");
+      handler += `context['${handlerName}'].call(${params}, e);}`;
    } else {
-      handler += "}";
+      handler = `context['${handlerName}'].bind(${params})`;
+    }
+    if (extraArgs) {
      ctx.addLine(`p${nodeID}.on['${eventName}'] = ${handler};`);
+    } else {
+      ctx.addLine(
+        `extra.handlers['${eventName}' + ${nodeID}] = extra.handlers['${eventName}' + ${nodeID}] || ${handler};`
+      );
+      ctx.addLine(`p${nodeID}.on['${eventName}'] = extra.handlers['${eventName}' + ${nodeID}];`);
    }
  }
 });
@@ -82,7 +83,6 @@ QWeb.addDirective({
    const refKey = `ref${ctx.generateID()}`;
    ctx.addLine(`const ${refKey} = ${ctx.interpolate(value)};`);
    addNodeHook("create", `context.__owl__.refs[${refKey}] = n.elm;`);
-    addNodeHook("destroy", `delete context.__owl__.refs[${refKey}];`);
  }
 });

@@ -104,8 +104,6 @@ QWeb.utils.transitionInsert = function(vn: VNode, name: string) {

  elm.classList.add(name + "-enter");
  elm.classList.add(name + "-enter-active");
-  elm.classList.remove(name + "-leave-active");
-  elm.classList.remove(name + "-leave-to");
  const finalize = () => {
    elm.classList.remove(name + "-enter-active");
    elm.classList.remove(name + "-enter-to");
@@ -124,9 +122,6 @@ QWeb.utils.transitionRemove = function(vn: VNode, name: string, rm: () => void)
  elm.classList.add(name + "-leave");
  elm.classList.add(name + "-leave-active");
  const finalize = () => {
-    if (!elm.classList.contains(name + "-leave-active")) {
-      return;
-    }
    elm.classList.remove(name + "-leave-active");
    elm.classList.remove(name + "-leave-to");
    rm();
@@ -194,32 +189,16 @@ QWeb.addDirective({
 QWeb.addDirective({
  name: "slot",
  priority: 80,
-  atNodeEncounter({ ctx, value, node, qweb }): boolean {
+  atNodeEncounter({ ctx, value }): boolean {
    const slotKey = ctx.generateID();
+    ctx.rootContext.shouldDefineOwner = true;
    ctx.addLine(
      `const slot${slotKey} = this.constructor.slots[context.__owl__.slotId + '_' + '${value}'];`
    );
    ctx.addIf(`slot${slotKey}`);
-    let parentNode = `c${ctx.parentNode}`;
-    if (!ctx.parentNode) {
-      ctx.rootContext.shouldDefineResult = true;
-      ctx.rootContext.shouldDefineUtils = true;
-      parentNode = `children${ctx.generateID()}`;
-      ctx.addLine(`let ${parentNode}= []`);
-      ctx.addLine(`result = {}`);
-    }
    ctx.addLine(
-      `slot${slotKey}.call(this, context.__owl__.scope, Object.assign({}, extra, {parentNode: ${parentNode}, parent: extra.parent || context}));`
+      `slot${slotKey}.call(this, context.__owl__.parent, Object.assign({}, extra, {parentNode: c${ctx.parentNode}, vars: extra.vars, parent: owner}));`
    );
-    if (!ctx.parentNode) {
-      ctx.addLine(`utils.defineProxy(result, ${parentNode}[0]);`);
-    }
-    if (node.hasChildNodes()) {
-      ctx.addElse();
-      const nodeCopy = <Element>node.cloneNode(true);
-      nodeCopy.removeAttribute("t-slot");
-      qweb._compileNode(nodeCopy, ctx);
-    }
    ctx.closeIf();
    return true;
  }
@@ -240,17 +219,7 @@ QWeb.addDirective({
    const type = node.getAttribute("type");
    let handler;
    let event = fullName.includes(".lazy") ? "change" : "input";
-
-    // we keep here a reference to the "base expression" (if the expression
-    // is `t-model="some.expr.value", then the base expression is "some.expr").
-    // This is necessary so we can capture it in the handler closure.
-    let expr = ctx.formatExpression(value);
-    const index = expr.lastIndexOf(".");
-    const baseExpr = expr.slice(0, index);
-    ctx.addLine(`let expr${nodeID} = ${baseExpr};`);
-
-    expr = `expr${nodeID}.${expr.slice(index + 1)}`;
-    const key = ctx.generateTemplateKey();
+    const expr = ctx.formatExpression(value);
    if (node.tagName === "select") {
      ctx.addLine(`p${nodeID}.props = {value: ${expr}};`);
      addNodeHook("create", `n.elm.value=${expr};`);
@@ -274,20 +243,9 @@ QWeb.addDirective({
      }
      handler = `(ev) => {${expr} = ${valueCode}}`;
    }
-    ctx.addLine(`extra.handlers[${key}] = extra.handlers[${key}] || (${handler});`);
-    ctx.addLine(`p${nodeID}.on['${event}'] = extra.handlers[${key}];`);
-  }
-});
-
-//------------------------------------------------------------------------------
-// t-key
-//------------------------------------------------------------------------------
-QWeb.addDirective({
-  name: "key",
-  priority: 45,
-  atNodeEncounter({ ctx, value }) {
-    let id = ctx.generateID();
-    ctx.addLine(`const nodeKey${id} = ${ctx.formatExpression(value)};`);
-    ctx.currentKey = `nodeKey${id}`;
+    ctx.addLine(
+      `extra.handlers['${event}' + ${nodeID}] = extra.handlers['${event}' + ${nodeID}] || (${handler});`
+    );
+    ctx.addLine(`p${nodeID}.on['${event}'] = extra.handlers['${event}' + ${nodeID}];`);
  }
 });
@@ -1,6 +1,6 @@
 import { EventBus } from "../core/event_bus";
 import { h, patch, VNode } from "../vdom/index";
-import { CompilationContext } from "./compilation_context";
+import { Context } from "./context";
 import { shallowEqual } from "../utils";
 import { addNS } from "../vdom/vdom";

@@ -36,7 +36,7 @@ interface Template {
 interface CompilationInfo {
  node: Element;
  qweb: QWeb;
-  ctx: CompilationContext;
+  ctx: Context;
  fullName: string;
  value: string;
 }
@@ -57,27 +57,19 @@ export interface Directive {
  finalize?(info: CompilationInfo): void;
 }

-interface QWebConfig {
-  templates?: string;
-  translateFn?(text: string): string;
-}
-
 //------------------------------------------------------------------------------
 // Const/global stuff/helpers
 //------------------------------------------------------------------------------

 const DISABLED_TAGS = ["input", "textarea", "button", "select", "option", "optgroup"];

-const TRANSLATABLE_ATTRS = ["label", "title", "placeholder", "alt"];
-
 const lineBreakRE = /[\r\n]/;
 const whitespaceRE = /\s+/g;

 const NODE_HOOKS_PARAMS = {
  create: "(_, n)",
  insert: "vn",
-  remove: "(vn, rm)",
-  destroy: "()"
+  remove: "(vn, rm)"
 };

 interface Utils {
@@ -87,7 +79,6 @@ interface Utils {
 }

 const UTILS: Utils = {
-  zero: Symbol("zero"),
  toObj(expr) {
    if (typeof expr === "string") {
      expr = expr.trim();
@@ -106,26 +97,14 @@ const UTILS: Utils = {
  shallowEqual,
  addNameSpace(vnode) {
    addNS(vnode.data, vnode.children, vnode.sel);
-  },
-  VDomArray: class VDomArray extends Array {},
-  vDomToString: function(vdom: VNode[]): string {
-    return vdom
-      .map(vnode => {
-        if (vnode.sel) {
-          const node = document.createElement(vnode.sel);
-          const result = patch(node, vnode);
-          return (<HTMLElement>result.elm).outerHTML;
-        } else {
-          return vnode.text;
-        }
-      })
-      .join();
  }
 };

 function parseXML(xml: string): Document {
  const parser = new DOMParser();

+  // we remove comments from the xml string
+  xml = xml.replace(/<!--[\s\S]*?-->/g, "");
  const doc = parser.parseFromString(xml, "text/xml");
  if (doc.getElementsByTagName("parsererror").length) {
    let msg = "Invalid XML in template.";
@@ -156,7 +135,6 @@ function parseXML(xml: string): Document {
 //------------------------------------------------------------------------------
 // QWeb rendering engine
 //------------------------------------------------------------------------------
-
 export class QWeb extends EventBus {
  templates: { [name: string]: Template };
  static utils = UTILS;
@@ -166,7 +144,7 @@ export class QWeb extends EventBus {
    name: 1,
    att: 1,
    attf: 1,
-    translation: 1
+    key: 1
  };
  static DIRECTIVES: Directive[] = [];

@@ -186,19 +164,15 @@ export class QWeb extends EventBus {
  // recursiveTemplates contains sub templates called with t-call, but which
  // ends up in recursive situations.  This is very similar to the slot situation,
  // as in we need to propagate the scope.
-  subTemplates = {};
+  recursiveFns = {};

  isUpdating: boolean = false;
-  translateFn?: QWebConfig["translateFn"];

-  constructor(config: QWebConfig = {}) {
+  constructor(data?: string) {
    super();
    this.templates = Object.create(QWeb.TEMPLATES);
-    if (config.templates) {
-      this.addTemplates(config.templates);
-    }
-    if (config.translateFn) {
-      this.translateFn = config.translateFn;
+    if (data) {
+      this.addTemplates(data);
    }
  }

@@ -368,19 +342,31 @@ export class QWeb extends EventBus {
    });
  }

-  _compile(name: string, elem: Element, parentContext?: CompilationContext): CompiledTemplate {
+  _compile(name: string, elem: Element, parentContext?: Context): CompiledTemplate {
    const isDebug = elem.attributes.hasOwnProperty("t-debug");
-    const ctx = new CompilationContext(name);
+    const ctx = new Context(name);
    if (elem.tagName !== "t") {
      ctx.shouldDefineResult = false;
    }
    if (parentContext) {
+      ctx.templates = Object.create(parentContext.templates);
      ctx.variables = Object.create(parentContext.variables);
-      ctx.parentNode = parentContext.parentNode || ctx.generateID();
+      ctx.nextID = parentContext.nextID + 1;
+      ctx.parentNode = parentContext.parentNode || ctx.nextID++;
      ctx.allowMultipleRoots = true;
      ctx.hasParentWidget = true;
      ctx.shouldDefineResult = false;
      ctx.addLine(`let c${ctx.parentNode} = extra.parentNode;`);
+
+      for (let v in parentContext.variables) {
+        let variable = <any>parentContext.variables[v];
+        if (variable.id) {
+          ctx.addLine(`let ${variable.id} = extra.fiber.vars.${variable.id}`);
+        }
+      }
+    }
+    if (parentContext) {
+      ctx.addLine("    Object.assign(context, extra.fiber.scope);");
    }
    this._compileNode(elem, ctx);

@@ -396,13 +382,12 @@ export class QWeb extends EventBus {
    }

    let code = ctx.generateCode();
-    const templateName = ctx.templateName.replace(/`/g, "'").slice(0, 200);
-    code.unshift(`    // Template name: "${templateName}"`);

    let template;
    try {
-      template = new Function("context, extra", code.join("\n")) as CompiledTemplate;
+      template = new Function("context", "extra", code.join("\n")) as CompiledTemplate;
    } catch (e) {
+      const templateName = ctx.templateName.replace(/`/g, "'");
      console.groupCollapsed(`Invalid Code generated by ${templateName}`);
      console.warn(code.join("\n"));
      console.groupEnd();
@@ -424,7 +409,7 @@ export class QWeb extends EventBus {
   * Generate code from an xml node
   *
   */
-  _compileNode(node: ChildNode, ctx: CompilationContext) {
+  _compileNode(node: ChildNode, ctx: Context) {
    if (!(node instanceof Element)) {
      // this is a text node, there are no directive to apply
      let text = node.textContent!;
@@ -434,17 +419,8 @@ export class QWeb extends EventBus {
        }
        text = text.replace(whitespaceRE, " ");
      }
-      if (this.translateFn) {
-        if ((node.parentNode as any).getAttribute("t-translation") !== "off") {
-          text = this.translateFn(text);
-        }
-      }
      if (ctx.parentNode) {
-        if (node.nodeType === 3) {
-          ctx.addLine(`c${ctx.parentNode}.push({text: \`${text}\`});`);
-        } else if (node.nodeType === 8) {
-          ctx.addLine(`c${ctx.parentNode}.push(h('!', \`${text}\`));`);
-        }
+        ctx.addLine(`c${ctx.parentNode}.push({text: \`${text}\`});`);
      } else if (ctx.parentTextNode) {
        ctx.addLine(`vn${ctx.parentTextNode}.text += \`${text}\`;`);
      } else {
@@ -458,19 +434,12 @@ export class QWeb extends EventBus {
      }
      return;
    }
-    if (ctx !== ctx.rootContext) {
-      ctx = ctx.subContext("currentKey", ctx.currentKey);
-    }

    const firstLetter = node.tagName[0];
    if (firstLetter === firstLetter.toUpperCase()) {
      // this is a component, we modify in place the xml document to change
      // <SomeComponent ... /> to <t t-component="SomeComponent" ... />
      node.setAttribute("t-component", node.tagName);
-    } else if (node.tagName !== "t" && node.hasAttribute("t-component")) {
-      throw new Error(
-        `Directive 't-component' can only be used on <t> nodes (used on a <${node.tagName}>)`
-      );
    }
    const attributes = (<Element>node).attributes;

@@ -480,7 +449,7 @@ export class QWeb extends EventBus {
      fullName: string;
    }[] = [];

-    const finalizers: typeof validDirectives = [];
+    let withHandlers = false;

    // maybe this is not optimal: we iterate on all attributes here, and again
    // just after for each directive.
@@ -491,21 +460,11 @@ export class QWeb extends EventBus {
        if (!(dName in QWeb.DIRECTIVE_NAMES)) {
          throw new Error(`Unknown QWeb directive: '${attrName}'`);
        }
-        if (node.tagName !== "t" && (attrName === "t-esc" || attrName === "t-raw")) {
-          const tNode = document.createElement("t");
-          tNode.setAttribute(attrName, node.getAttribute(attrName)!);
-          for (let child of Array.from(node.childNodes)) {
-            tNode.appendChild(child);
-          }
-          node.appendChild(tNode);
-          node.removeAttribute(attrName);
-        }
      }
    }

    const DIR_N = QWeb.DIRECTIVES.length;
    const ATTR_N = attributes.length;
-    let withHandlers = false;
    for (let i = 0; i < DIR_N; i++) {
      let directive = QWeb.DIRECTIVES[i];
      let fullName;
@@ -526,11 +485,7 @@ export class QWeb extends EventBus {
        }
      }
    }
-
    for (let { directive, value, fullName } of validDirectives) {
-      if (directive.finalize) {
-        finalizers.push({ directive, value, fullName });
-      }
      if (directive.atNodeEncounter) {
        const isDone = directive.atNodeEncounter({
          node,
@@ -540,9 +495,6 @@ export class QWeb extends EventBus {
          value
        });
        if (isDone) {
-          for (let { directive, value, fullName } of finalizers) {
-            directive.finalize!({ node, qweb: this, ctx, fullName, value });
-          }
          return;
        }
      }
@@ -551,6 +503,7 @@ export class QWeb extends EventBus {
    if (node.nodeName !== "t") {
      let nodeID = this._compileGenericNode(node, ctx, withHandlers);
      ctx = ctx.withParent(nodeID);
+      ctx = ctx.subContext("currentKey", ctx.lastNodeKey);
      let nodeHooks = {};
      let addNodeHook = function(hook, handler) {
        nodeHooks[hook] = nodeHooks[hook] || [];
@@ -600,16 +553,14 @@ export class QWeb extends EventBus {
      ctx.addLine(`utils.addNameSpace(vn${ctx.parentNode});`);
    }

-    for (let { directive, value, fullName } of finalizers) {
-      directive.finalize!({ node, qweb: this, ctx, fullName, value });
+    for (let { directive, value, fullName } of validDirectives) {
+      if (directive.finalize) {
+        directive.finalize({ node, qweb: this, ctx, fullName, value });
+      }
    }
  }

-  _compileGenericNode(
-    node: ChildNode,
-    ctx: CompilationContext,
-    withHandlers: boolean = true
-  ): number {
+  _compileGenericNode(node: ChildNode, ctx: Context, withHandlers: boolean = true): number {
    // nodeType 1 is generic tag
    if (node.nodeType !== 1) {
      throw new Error("unsupported node type");
@@ -644,24 +595,19 @@ export class QWeb extends EventBus {

    for (let i = 0; i < attributes.length; i++) {
      let name = attributes[i].name;
-      let value = attributes[i].textContent!;
-
-      if (this.translateFn && TRANSLATABLE_ATTRS.includes(name)) {
-        value = this.translateFn(value);
-      }
+      const value = attributes[i].textContent!;

      // regular attributes
      if (!name.startsWith("t-") && !(<Element>node).getAttribute("t-attf-" + name)) {
        const attID = ctx.generateID();
        if (name === "class") {
-          if ((value = value.trim())) {
-            let classDef = value
-              .split(/\s+/)
-              .map(a => `'${a}':true`)
-              .join(",");
-            classObj = `_${ctx.generateID()}`;
-            ctx.addLine(`let ${classObj} = {${classDef}};`);
-          }
+          let classDef = value
+            .trim()
+            .split(/\s+/)
+            .map(a => `'${a}':true`)
+            .join(",");
+          classObj = `_${ctx.generateID()}`;
+          ctx.addLine(`let ${classObj} = {${classDef}};`);
        } else {
          ctx.addLine(`var _${attID} = '${value}';`);
          if (!name.match(/^[a-zA-Z]+$/)) {
@@ -677,7 +623,7 @@ export class QWeb extends EventBus {
      if (name.startsWith("t-att-")) {
        let attName = name.slice(6);
        const v = ctx.getValue(value);
-        let formattedValue = typeof v === "string" ? ctx.formatExpression(v) : `scope.${v.id}`;
+        let formattedValue = v.id || ctx.formatExpression(v);

        if (attName === "class") {
          ctx.rootContext.shouldDefineUtils = true;
@@ -735,7 +681,14 @@ export class QWeb extends EventBus {
      }
    }
    let nodeID = ctx.generateID();
-    let nodeKey = ctx.currentKey || nodeID;
+    let nodeKey: any = (<Element>node).getAttribute("t-key");
+    if (nodeKey) {
+      ctx.addLine(`const nodeKey${nodeID} = ${ctx.formatExpression(nodeKey)}`);
+      nodeKey = `nodeKey${nodeID}`;
+      ctx.lastNodeKey = nodeKey;
+    } else {
+      nodeKey = nodeID;
+    }
    const parts = [`key:${nodeKey}`];
    if (attrs.length + tattrs.length > 0) {
      parts.push(`attrs:{${attrs.join(",")}}`);
@@ -770,7 +723,7 @@ export class QWeb extends EventBus {
    return nodeID;
  }

-  _compileChildren(node: ChildNode, ctx: CompilationContext) {
+  _compileChildren(node: ChildNode, ctx: Context) {
    if (node.childNodes.length > 0) {
      for (let child of Array.from(node.childNodes)) {
        this._compileNode(child, ctx);
@@ -1,6 +1,6 @@
 import { Component } from "../component/component";
 import { xml } from "../tags";
-import { Destination, RouterEnv } from "./router";
+import { Destination, RouterEnv } from "./Router";

 type Props = Destination;

@@ -148,7 +148,7 @@ export class Router {
  //--------------------------------------------------------------------------

  private setUrlFromPath(path: string) {
-    const separator = this.mode === "hash" ? location.pathname : "";
+    const separator = this.mode === "hash" ? "/" : "";
    const url = location.origin + separator + path;
    if (url !== window.location.href) {
      window.history.pushState({}, path, url);
@@ -1,156 +0,0 @@
-import { Component } from "./component/component";
-import { Env } from "./component/component";
-import { Context, useContextWithCB } from "./context";
-import { onWillUpdateProps } from "./hooks";
-
-/**
- * Owl Store
- *
- * We have here:
- * - a Store class
- * - useStore hook
- * - useDispatch hook
- * - useGetters hook
- *
- * The Owl store is our answer to the problem of managing complex state across
- * components. The main idea is that the store owns some state, allow external
- * code to modify it through actions, and for each state changes,
- * connected component will be notified, and updated if necessary.
- *
- * Note that this code is partly inspired by VueX and React/Redux
- */
-
-//------------------------------------------------------------------------------
-// Store Definition
-//------------------------------------------------------------------------------
-
-export type Action = ({ state, dispatch, env, getters }, ...payload: any) => any;
-export type Getter = ({ state: any, getters }, payload?) => any;
-
-interface StoreConfig {
-  env?: Env;
-  state?: any;
-  actions?: { [name: string]: Action };
-  getters?: { [name: string]: Getter };
-}
-
-export class Store extends Context {
-  actions: any;
-  env: any;
-  getters: { [name: string]: (payload?) => any };
-  updateFunctions: { [key: number]: (() => boolean)[] };
-
-  constructor(config: StoreConfig) {
-    super(config.state);
-    this.actions = config.actions;
-    this.env = config.env;
-    this.getters = {};
-    this.updateFunctions = [];
-    if (config.getters) {
-      const firstArg = {
-        state: this.state,
-        getters: this.getters
-      };
-      for (let g in config.getters) {
-        this.getters[g] = config.getters[g].bind(this, firstArg);
-      }
-    }
-  }
-
-  dispatch(action: string, ...payload: any): Promise<void> | void {
-    if (!this.actions[action]) {
-      throw new Error(`[Error] action ${action} is undefined`);
-    }
-    const result = this.actions[action](
-      {
-        dispatch: this.dispatch.bind(this),
-        env: this.env,
-        state: this.state,
-        getters: this.getters
-      },
-      ...payload
-    );
-    return result;
-  }
-}
-
-interface SelectorOptions {
-  store?: Store;
-  isEqual?: (a: any, b: any) => boolean;
-  onUpdate?: (result: any) => any;
-}
-
-const isStrictEqual = (a, b) => a === b;
-
-export function useStore(selector, options: SelectorOptions = {}): any {
-  const component: Component<any, any> = Component.current!;
-  const componentId = component.__owl__.id;
-  const store = options.store || (component.env.store as Store);
-  if (!(store instanceof Store)) {
-    throw new Error(`No store found when connecting '${component.constructor.name}'`);
-  }
-  let result = selector(store.state, component.props);
-  const hashFn = store.observer.revNumber.bind(store.observer);
-  let revNumber = hashFn(result);
-  const isEqual = options.isEqual || isStrictEqual;
-  if (!store.updateFunctions[componentId]) {
-    store.updateFunctions[componentId] = [];
-  }
-  function selectCompareUpdate(state, props): boolean {
-    const oldResult = result;
-    result = selector(state, props);
-    const newRevNumber = hashFn(result);
-    if ((newRevNumber > 0 && revNumber !== newRevNumber) || !isEqual(oldResult, result)) {
-      revNumber = newRevNumber;
-      if (options.onUpdate) {
-        options.onUpdate(result);
-      }
-      return true;
-    }
-    return false;
-  }
-  store.updateFunctions[componentId].push(function(): boolean {
-    return selectCompareUpdate(store!.state, component.props);
-  });
-
-  useContextWithCB(store, component, function(): Promise<void> | void {
-    let shouldRender = false;
-    for (let fn of store.updateFunctions[componentId]) {
-      shouldRender = fn() || shouldRender;
-    }
-    if (shouldRender) {
-      return component.render();
-    }
-  });
-  onWillUpdateProps(props => {
-    selectCompareUpdate(store.state, props);
-  });
-
-  const __destroy = component.__destroy;
-  component.__destroy = parent => {
-    delete store.updateFunctions[componentId];
-    __destroy.call(component, parent);
-  };
-
-  if (typeof result !== "object") {
-    return result;
-  }
-  return new Proxy(result, {
-    get(target, k) {
-      return result[k];
-    },
-    set(target, k, v) {
-      throw new Error("Store state should only be modified through actions");
-    }
-  });
-}
-
-export function useDispatch(store?: Store): Store["dispatch"] {
-  store = store || (Component.current!.env.store as Store);
-  return store.dispatch.bind(store);
-}
-
-export function useGetters(store?: Store): Store["getters"] {
-  store = store || (Component.current!.env.store as Store);
-  return store.getters;
-}
@@ -0,0 +1,147 @@
+import { Component, Env, Fiber } from "../component/component";
+import { VNode } from "../vdom/index";
+
+//------------------------------------------------------------------------------
+// Connect function
+//------------------------------------------------------------------------------
+
+type HashFunction = (a: any, b: any) => number;
+
+export class ConnectedComponent<T extends Env, P> extends Component<T, P> {
+  deep: boolean = true;
+  getStore(env) {
+    return env.store;
+  }
+
+  storeProps: any;
+
+  hashFunction: HashFunction = (storeProps, options) => {
+    const revFn = (this.__owl__ as any).revFn;
+    const rev = revFn(storeProps);
+    if (rev > 0) {
+      return rev;
+    }
+    let hash = 0;
+    for (let key in storeProps) {
+      const val = storeProps[key];
+      const hashVal = revFn(val);
+      if (hashVal === 0) {
+        if (val !== options.prevStoreProps[key]) {
+          options.didChange = true;
+        }
+      } else {
+        hash += hashVal;
+      }
+    }
+    return hash;
+  };
+
+  static mapStoreToProps(storeState, ownProps, getters) {
+    return {};
+  }
+
+  dispatch(name, ...payload) {
+    return (this.__owl__ as any).store.dispatch(name, ...payload);
+  }
+
+  /**
+   * Need to do this here so 'deep' can be overrided by subcomponent easily
+   */
+  async __prepareAndRender(fiber: Fiber<P>): Promise<VNode> {
+    const store = this.getStore(this.env);
+    const ownProps = this.props || {};
+    this.storeProps = (<any>this.constructor).mapStoreToProps(store.state, ownProps, store.getters);
+    const observer = store.observer;
+    const revFn = this.deep ? observer.deepRevNumber : observer.revNumber;
+    (this.__owl__ as any).store = store;
+    (this.__owl__ as any).ownProps = this.props;
+    (this.__owl__ as any).revFn = revFn.bind(observer);
+    (this.__owl__ as any).storeHash = this.hashFunction(this.storeProps, {
+      prevStoreProps: this.storeProps
+    });
+    (this.__owl__ as any).rev = observer.rev;
+    return super.__prepareAndRender(fiber);
+  }
+  /**
+   * We do not use the mounted hook here for a subtle reason: we want the
+   * updates to be called for the parents before the children.  However,
+   * if we use the mounted hook, this will be done in the reverse order.
+   */
+  __callMounted() {
+    (this.__owl__ as any).store.on("update", this, this.__checkUpdate);
+    super.__callMounted();
+  }
+  __callWillUnmount() {
+    (this.__owl__ as any).store.off("update", this);
+    super.__callWillUnmount();
+  }
+  __destroy(parent: any) {
+    (this.__owl__ as any).store.off("update", this);
+    super.__destroy(parent);
+  }
+
+  async render(force: boolean = false) {
+    this.__updateStoreProps(this.props);
+
+    // this is quite technical, so this deserves some explanation.
+    // When we have a connected component, it can be updated for 3 reasons:
+    // - some internal state changes (this will go through this method)
+    // - some props changes (if a parent is changed and need to rerender itself)
+    // - a store update
+    //
+    // It is possible (with connected component and parent) to have the following
+    // situation: the parent component is rendered first (from its state change),
+    // then immediately after, it is rendered (from store update). Then, if the
+    // __checkUpdate method is immediately over, the children component will
+    // be rendered again by the store update, even though it is supposed to be
+    // destroyed by the first rendering.
+    //
+    // So, the solution is to keep the information that there is a current
+    // rendering occuring with the same store state, the same props, and return
+    // that in the __checkUpdate method.  To do this, we use the renderPromise
+    // deferred, which is not used by the component system once the
+    // component is ready, so we can use it for our own purpose.
+    (this.__owl__ as any).renderPromise = super.render(force);
+    return (this.__owl__ as any).renderPromise;
+  }
+
+  async __updateProps(nextProps: P, f, s, v) {
+    this.__updateStoreProps(nextProps);
+    return super.__updateProps(nextProps, f, s, v);
+  }
+
+  __updateStoreProps(nextProps): boolean {
+    const __owl__ = this.__owl__ as any;
+    const store = __owl__.store;
+    const observer = store.observer;
+    if (observer.rev === __owl__.rev && nextProps === __owl__.ownProps) {
+      return false;
+    }
+
+    const storeProps = (<any>this.constructor).mapStoreToProps(
+      store.state,
+      nextProps,
+      store.getters
+    );
+    const options = { prevStoreProps: this.storeProps, didChange: false };
+    const storeHash = this.hashFunction(storeProps, options);
+    this.storeProps = storeProps;
+    let didChange = options.didChange;
+    if (storeHash !== __owl__.storeHash) {
+      __owl__.storeHash = storeHash;
+      didChange = true;
+    }
+    __owl__.rev = store.observer.rev;
+    __owl__.ownProps = nextProps;
+    return didChange;
+  }
+
+  async __checkUpdate() {
+    const didChange = this.__updateStoreProps(this.props);
+    if (didChange) {
+      return this.render();
+    }
+    // see note in render method
+    return (this.__owl__ as any).renderPromise;
+  }
+}
@@ -0,0 +1,107 @@
+import { Env } from "../component/component";
+import { EventBus } from "../core/event_bus";
+import { Observer } from "../core/observer";
+
+/**
+ * Owl Store
+ *
+ * We have here:
+ * - a Store class
+ * - the ConnectedComponent class
+ *
+ * The Owl store is our answer to the problem of managing complex state across
+ * components. The main idea is that the store owns some state, allow external
+ * code to modify it through actions, and for each state changes,
+ * connected component will be notified, and updated if necessary.
+ *
+ * Note that this code is partly inspired by VueX and React/Redux
+ */
+
+//------------------------------------------------------------------------------
+// Store Definition
+//------------------------------------------------------------------------------
+
+export type Action = ({ state, dispatch, env, getters }, ...payload: any) => any;
+export type Getter = ({ state: any, getters }, payload?) => any;
+
+interface StoreConfig {
+  env?: Env;
+  state?: any;
+  actions?: { [name: string]: Action };
+  getters?: { [name: string]: Getter };
+}
+
+interface StoreOption {
+  debug?: boolean;
+}
+
+export class Store extends EventBus {
+  state: any;
+  actions: any;
+  mutations: any;
+  debug: boolean;
+  env: any;
+  observer: Observer;
+  getters: { [name: string]: (payload?) => any };
+
+  constructor(config: StoreConfig, options: StoreOption = {}) {
+    super();
+    this.debug = options.debug || false;
+    this.actions = config.actions;
+    this.env = config.env;
+    this.observer = new Observer();
+    this.observer.notifyCB = this.__notifyComponents.bind(this);
+    this.state = this.observer.observe(config.state || {});
+    this.getters = {};
+    if (config.getters) {
+      const firstArg = {
+        state: this.state,
+        getters: this.getters
+      };
+      for (let g in config.getters) {
+        this.getters[g] = config.getters[g].bind(this, firstArg);
+      }
+    }
+  }
+
+  dispatch(action: string, ...payload: any): Promise<void> | void {
+    if (!this.actions[action]) {
+      throw new Error(`[Error] action ${action} is undefined`);
+    }
+    const result = this.actions[action](
+      {
+        dispatch: this.dispatch.bind(this),
+        env: this.env,
+        state: this.state,
+        getters: this.getters
+      },
+      ...payload
+    );
+    return result;
+  }
+
+  /**
+   * Instead of using trigger to emit an update event, we actually implement
+   * our own function to do that.  The reason is that we need to be smarter than
+   * a simple trigger function: we need to wait for parent components to be
+   * done before doing children components.  The reason is that if an update
+   * as an effect of destroying a children, we do not want to call the
+   * mapStoreToProps function of the child, nor rendering it.
+   *
+   * This method is not optimal if we have a bunch of asynchronous components:
+   * we wait sequentially for each component to be completed before updating the
+   * next.  However, the only things that matters is that children are updated
+   * after their parents.  So, this could be optimized by being smarter, and
+   * updating all widgets concurrently, except for parents/children.
+   */
+  async __notifyComponents() {
+    const subs = this.subscriptions.update || [];
+    for (let i = 0, iLen = subs.length; i < iLen; i++) {
+      const sub = subs[i];
+      const shouldCallback = sub.owner ? sub.owner.__owl__.isMounted : true;
+      if (shouldCallback) {
+        await sub.callback.call(sub.owner);
+      }
+    }
+  }
+}
@@ -5,7 +5,7 @@
 *
 * - whenReady
 * - loadJS
- * - loadFile
+ * - loadTemplates
 * - escape
 * - debounce
 */
@@ -43,7 +43,7 @@ export function loadJS(url: string): Promise<void> {
  return promise;
 }

-export async function loadFile(url: string): Promise<string> {
+export async function loadTemplates(url: string): Promise<string> {
  const result = await fetch(url);
  if (!result.ok) {
    throw new Error("Error while fetching xml templates");
@@ -1,27 +0,0 @@
-import { VNode, h } from "./vdom";
-
-const parser = new DOMParser();
-
-export function htmlToVDOM(html: string): VNode[] {
-  const doc = parser.parseFromString(html, "text/html");
-  const result: VNode[] = [];
-  for (let child of doc.body.childNodes) {
-    result.push(htmlToVNode(child));
-  }
-  return result;
-}
-
-function htmlToVNode(node: ChildNode): VNode {
-  if (!(node instanceof Element)) {
-    return { text: node.textContent! } as VNode;
-  }
-  const attrs = {};
-  for (let attr of node.attributes) {
-    attrs[attr.name] = attr.textContent;
-  }
-  const children: VNode[] = [];
-  for (let c of node.childNodes) {
-    children.push(htmlToVNode(c));
-  }
-  return h((node as Element).tagName, { attrs }, children);
-}
@@ -219,7 +219,7 @@ function updateClass(oldVnode: VNode, vnode: VNode): void {
  elm = vnode.elm as Element;

  for (name in oldClass) {
-    if (name && !klass[name]) {
+    if (!klass[name]) {
      elm.classList.remove(name);
    }
  }
@@ -101,7 +101,7 @@ function isVnode(vnode: any): vnode is VNode {

 type KeyToIndexMap = { [key: string]: number };

-type ArraysOf<T> = { [K in keyof T]: T[K][] };
+type ArraysOf<T> = { [K in keyof T]: (T[K])[] };

 type ModuleHooks = ArraysOf<Module>;

@@ -176,12 +176,18 @@ export function init(modules: Array<Partial<Module>>, domApi?: DOMAPI) {
      }
      vnode.elm = api.createComment(vnode.text as string);
    } else if (sel !== undefined) {
-      const elm =
-        vnode.elm ||
-        (vnode.elm =
-          isDef(data) && isDef((i = (data as VNodeData).ns))
-            ? api.createElementNS(i, sel)
-            : api.createElement(sel));
+      // Parse selector
+      const hashIdx = sel.indexOf("#");
+      const dotIdx = sel.indexOf(".", hashIdx);
+      const hash = hashIdx > 0 ? hashIdx : sel.length;
+      const dot = dotIdx > 0 ? dotIdx : sel.length;
+      const tag = hashIdx !== -1 || dotIdx !== -1 ? sel.slice(0, Math.min(hash, dot)) : sel;
+      const elm = (vnode.elm =
+        isDef(data) && isDef((i = (data as VNodeData).ns))
+          ? api.createElementNS(i, tag)
+          : api.createElement(tag));
+      if (hash < dot) elm.setAttribute("id", sel.slice(hash + 1, dot));
+      if (dotIdx > 0) elm.setAttribute("class", sel.slice(dot + 1).replace(/\./g, " "));
      for (i = 0, iLen = cbs.create.length; i < iLen; ++i) cbs.create[i](emptyNode, vnode);
      if (array(children)) {
        for (i = 0, iLen = children.length; i < iLen; ++i) {
@@ -559,15 +565,13 @@ type ArrayOrElement<T> = T | T[];
 type VNodeChildren = ArrayOrElement<VNodeChildElement>;

 export function addNS(data: any, children: VNodes | undefined, sel: string | undefined): void {
-  if (sel === "dummy") {
-    // we do not need to add the namespace on dummy elements, they come from a
-    // subcomponent, which will handle the namespace itself
-    return;
-  }
  data.ns = "http://www.w3.org/2000/svg";
  if (sel !== "foreignObject" && children !== undefined) {
    for (let i = 0, iLen = children.length; i < iLen; ++i) {
      const child = children[i];
+      if (child === null) {
+        continue;
+      }
      let childData = child.data;
      if (childData !== undefined) {
        addNS(childData, (child as VNode).children as VNodes, child.sel);
@@ -1,152 +1,105 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP

 exports[`animations t-transition combined with component 1`] = `
-"function anonymous(context, extra
+"function anonymous(context,extra
 ) {
-    // Template name: \\"Parent\\"
    let utils = this.constructor.utils;
    let QWeb = this.constructor;
    let parent = context;
-    let scope = Object.create(context);
+    let owner = context;
    var h = this.h;
    let c1 = [], p1 = {key:1};
    var vn1 = h('div', p1, c1);
+    result = vn1;
    //COMPONENT
-    let k3 = \`__4__\`;
-    let w2 = k3 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[k3]] : false;
-    let props2 = {};
-    if (w2 && w2.__owl__.currentFiber && !w2.__owl__.vnode) {
-        w2.destroy();
-        w2 = false;
+    let def3;
+    let w4 = 4 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[4]] : false;
+    let _2_index = c1.length;
+    c1.push(null);
+    let props4 = {};
+    if (w4 && w4.__owl__.currentFiber && !w4.__owl__.vnode) {
+        if (utils.shallowEqual(props4, w4.__owl__.currentFiber.props)) {
+            def3 = w4.__owl__.currentFiber.promise;
+        } else {
+            w4.destroy();
+            w4 = false;
+        }
    }
-    if (w2) {
-        w2.__updateProps(props2, extra.fiber, undefined);
-        let pvnode = w2.__owl__.pvnode;
-        c1.push(pvnode);
-    } else {
-        let componentKey2 = \`Child\`;
-        let W2 = context.constructor.components[componentKey2] || QWeb.components[componentKey2]|| scope['Child'];
-        if (!W2) {throw new Error('Cannot find the definition of component \\"' + componentKey2 + '\\"')}
-        w2 = new W2(parent, props2);
-        const __patch2 = w2.__patch;
-        w2.__patch = fiber => {__patch2.call(w2, fiber); if(!w2.__owl__.transitionInserted){w2.__owl__.transitionInserted = true;utils.transitionInsert(w2.__owl__.vnode, 'chimay');}};
-        parent.__owl__.cmap[k3] = w2.__owl__.id;
-        let fiber = w2.__prepare(extra.fiber, undefined, () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
-        let pvnode = h('dummy', {key: k3, hook: {remove() {},destroy(vn) {let finalize = () => {
-          w2.destroy();
+    if (!w4) {
+        let componentKey4 = \`Child\`;
+        let W4 = context.constructor.components[componentKey4] || QWeb.components[componentKey4]|| context['Child'];
+        if (!W4) {throw new Error('Cannot find the definition of component \\"' + componentKey4 + '\\"')}
+        w4 = new W4(parent, props4);
+        parent.__owl__.cmap[4] = w4.__owl__.id;
+        def3 = w4.__prepare(extra.fiber, undefined, undefined);
+        def3 = def3.then(vnode=>{if (w4.__owl__.isDestroyed){return}let pvnode=h(vnode.sel, {key: 4, hook: {insert(vn) {let nvn=w4.__mount(vnode, pvnode.elm);pvnode.elm=nvn.elm;utils.transitionInsert(vn, 'chimay');},remove() {},destroy(vn) {let finalize = () => {
+          w4.destroy();
        };
-        delete w2.__owl__.transitionInserted;
-        utils.transitionRemove(vn, 'chimay', finalize);}}});
-        c1.push(pvnode);
-        w2.__owl__.pvnode = pvnode;
+        utils.transitionRemove(vn, 'chimay', finalize);}}});c1[_2_index]=pvnode;w4.__owl__.pvnode = pvnode;});
+    } else {
+        def3 = def3 || w4.__updateProps(props4, extra.fiber, undefined, undefined);
+        def3 = def3.then(()=>{if (w4.__owl__.isDestroyed) {return};let pvnode=w4.__owl__.pvnode;c1[_2_index]=pvnode;});
    }
-    w2.__owl__.parentLastFiberId = extra.fiber.id;
+    extra.promises.push(def3);
    return vn1;
 }"
 `;

 exports[`animations t-transition combined with t-component and t-if 1`] = `
-"function anonymous(context, extra
+"function anonymous(context,extra
 ) {
-    // Template name: \\"Parent\\"
    let utils = this.constructor.utils;
    let QWeb = this.constructor;
    let parent = context;
-    let scope = Object.create(context);
+    let owner = context;
    var h = this.h;
    let c1 = [], p1 = {key:1};
    var vn1 = h('div', p1, c1);
-    if (scope['state'].display) {
+    result = vn1;
+    if (context['state'].display) {
        //COMPONENT
-        let k3 = \`__4__\`;
-        let w2 = k3 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[k3]] : false;
-        let props2 = {};
-        if (w2 && w2.__owl__.currentFiber && !w2.__owl__.vnode) {
-            w2.destroy();
-            w2 = false;
+        let def3;
+        let w4 = 4 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[4]] : false;
+        let _2_index = c1.length;
+        c1.push(null);
+        let props4 = {};
+        if (w4 && w4.__owl__.currentFiber && !w4.__owl__.vnode) {
+            if (utils.shallowEqual(props4, w4.__owl__.currentFiber.props)) {
+                def3 = w4.__owl__.currentFiber.promise;
+            } else {
+                w4.destroy();
+                w4 = false;
+            }
        }
-        if (w2) {
-            w2.__updateProps(props2, extra.fiber, undefined);
-            let pvnode = w2.__owl__.pvnode;
-            c1.push(pvnode);
-        } else {
-            let componentKey2 = \`Child\`;
-            let W2 = context.constructor.components[componentKey2] || QWeb.components[componentKey2]|| scope['Child'];
-            if (!W2) {throw new Error('Cannot find the definition of component \\"' + componentKey2 + '\\"')}
-            w2 = new W2(parent, props2);
-            const __patch2 = w2.__patch;
-            w2.__patch = fiber => {__patch2.call(w2, fiber); if(!w2.__owl__.transitionInserted){w2.__owl__.transitionInserted = true;utils.transitionInsert(w2.__owl__.vnode, 'chimay');}};
-            parent.__owl__.cmap[k3] = w2.__owl__.id;
-            let fiber = w2.__prepare(extra.fiber, undefined, () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
-            let pvnode = h('dummy', {key: k3, hook: {remove() {},destroy(vn) {let finalize = () => {
-          w2.destroy();
+        if (!w4) {
+            let componentKey4 = \`Child\`;
+            let W4 = context.constructor.components[componentKey4] || QWeb.components[componentKey4]|| context['Child'];
+            if (!W4) {throw new Error('Cannot find the definition of component \\"' + componentKey4 + '\\"')}
+            w4 = new W4(parent, props4);
+            parent.__owl__.cmap[4] = w4.__owl__.id;
+            def3 = w4.__prepare(extra.fiber, undefined, undefined);
+            def3 = def3.then(vnode=>{if (w4.__owl__.isDestroyed){return}let pvnode=h(vnode.sel, {key: 4, hook: {insert(vn) {let nvn=w4.__mount(vnode, pvnode.elm);pvnode.elm=nvn.elm;utils.transitionInsert(vn, 'chimay');},remove() {},destroy(vn) {let finalize = () => {
+          w4.destroy();
        };
-        delete w2.__owl__.transitionInserted;
-        utils.transitionRemove(vn, 'chimay', finalize);}}});
-            c1.push(pvnode);
-            w2.__owl__.pvnode = pvnode;
-        }
-        w2.__owl__.parentLastFiberId = extra.fiber.id;
-    }
-    return vn1;
-}"
-`;
-
-exports[`animations t-transition combined with t-component, remove and re-add before transitionend 1`] = `
-"function anonymous(context, extra
-) {
-    // Template name: \\"__template__2\\"
-    let utils = this.constructor.utils;
-    let QWeb = this.constructor;
-    let parent = context;
-    let scope = Object.create(context);
-    var h = this.h;
-    let c1 = [], p1 = {key:1};
-    var vn1 = h('div', p1, c1);
-    if (scope['state'].flag) {
-        //COMPONENT
-        let k3 = \`__4__\`;
-        let w2 = k3 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[k3]] : false;
-        let props2 = {};
-        if (w2 && w2.__owl__.currentFiber && !w2.__owl__.vnode) {
-            w2.destroy();
-            w2 = false;
-        }
-        if (w2) {
-            w2.__updateProps(props2, extra.fiber, undefined);
-            let pvnode = w2.__owl__.pvnode;
-            c1.push(pvnode);
+        utils.transitionRemove(vn, 'chimay', finalize);}}});c1[_2_index]=pvnode;w4.__owl__.pvnode = pvnode;});
        } else {
-            let componentKey2 = \`Child\`;
-            let W2 = context.constructor.components[componentKey2] || QWeb.components[componentKey2]|| scope['Child'];
-            if (!W2) {throw new Error('Cannot find the definition of component \\"' + componentKey2 + '\\"')}
-            w2 = new W2(parent, props2);
-            const __patch2 = w2.__patch;
-            w2.__patch = fiber => {__patch2.call(w2, fiber); if(!w2.__owl__.transitionInserted){w2.__owl__.transitionInserted = true;utils.transitionInsert(w2.__owl__.vnode, 'chimay');}};
-            parent.__owl__.cmap[k3] = w2.__owl__.id;
-            let fiber = w2.__prepare(extra.fiber, undefined, () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
-            let pvnode = h('dummy', {key: k3, hook: {remove() {},destroy(vn) {let finalize = () => {
-          w2.destroy();
-        };
-        delete w2.__owl__.transitionInserted;
-        utils.transitionRemove(vn, 'chimay', finalize);}}});
-            c1.push(pvnode);
-            w2.__owl__.pvnode = pvnode;
+            def3 = def3 || w4.__updateProps(props4, extra.fiber, undefined, undefined);
+            def3 = def3.then(()=>{if (w4.__owl__.isDestroyed) {return};let pvnode=w4.__owl__.pvnode;c1[_2_index]=pvnode;});
        }
-        w2.__owl__.parentLastFiberId = extra.fiber.id;
+        extra.promises.push(def3);
    }
    return vn1;
 }"
 `;

 exports[`animations t-transition with no delay/duration 1`] = `
-"function anonymous(context, extra
+"function anonymous(context,extra
 ) {
-    // Template name: \\"test\\"
    let utils = this.constructor.utils;
    var h = this.h;
    let c1 = [], p1 = {key:1};
    var vn1 = h('span', p1, c1);
+    result = vn1;
    p1.hook = {
      insert: vn => {
        utils.transitionInsert(vn, 'jupiler');
@@ -161,13 +114,13 @@ exports[`animations t-transition with no delay/duration 1`] = `
 `;

 exports[`animations t-transition, on a simple node (insert) 1`] = `
-"function anonymous(context, extra
+"function anonymous(context,extra
 ) {
-    // Template name: \\"test\\"
    let utils = this.constructor.utils;
    var h = this.h;
    let c1 = [], p1 = {key:1};
    var vn1 = h('span', p1, c1);
+    result = vn1;
    p1.hook = {
      insert: vn => {
        utils.transitionInsert(vn, 'chimay');
@@ -1,5 +0,0 @@
-// Jest Snapshot v1, https://goo.gl/fbAQLP
-
-exports[`various scenarios scenarios with async store updates and some components events 1`] = `"<div><button>Do stuff</button><div><span>Attachment 100</span><span>Name: text.txt</span></div></div>"`;
-
-exports[`various scenarios scenarios with async store updates and some components events 2`] = `"<div><button>Do stuff</button></div>"`;
@@ -1,15 +1,13 @@
 import { Component, Env } from "../src/component/component";
 import { QWeb } from "../src/qweb/index";
 import { useState, useRef } from "../src/hooks";
-import { xml } from "../src/tags";
 import {
  makeDeferred,
  makeTestFixture,
  makeTestEnv,
  patchNextFrame,
  renderToDOM,
-  unpatchNextFrame,
-  nextTick
+  unpatchNextFrame
 } from "./helpers";

 //------------------------------------------------------------------------------
@@ -31,7 +29,6 @@ let cssEl: HTMLElement;
 beforeEach(() => {
  fixture = makeTestFixture();
  env = makeTestEnv();
-  Component.env = env;
  qweb = new QWeb();
 });

@@ -111,7 +108,7 @@ describe("animations", () => {
    class TestWidget extends Widget {
      state = useState({ hide: false });
    }
-    const widget = new TestWidget();
+    const widget = new TestWidget(env);

    // insert widget into the DOM
    let def = makeDeferred();
@@ -154,7 +151,7 @@ describe("animations", () => {
      state = useState({ hide: false });
      span = useRef("span");
    }
-    const widget = new TestWidget();
+    const widget = new TestWidget(env);

    // insert widget into the DOM
    let def = makeDeferred();
@@ -183,7 +180,7 @@ describe("animations", () => {
    class Parent extends Widget {
      static components = { Child: Child };
    }
-    const widget = new Parent();
+    const widget = new Parent(env);

    let def = makeDeferred();
    var spanNode;
@@ -223,7 +220,7 @@ describe("animations", () => {
      static components = { Child: Child };
      state = useState({ display: true });
    }
-    const widget = new Parent();
+    const widget = new Parent(env);

    let def = makeDeferred();
    var spanNode;
@@ -254,11 +251,11 @@ describe("animations", () => {
    widget.state.display = false;
    patchNextFrame(cb => {
      expect(fixture.innerHTML).toBe(
-        '<div><span class="chimay-leave chimay-leave-active" data-owl-key="__4__">blue</span></div>'
+        '<div><span class="chimay-leave chimay-leave-active" data-owl-key="4">blue</span></div>'
      );
      cb();
      expect(fixture.innerHTML).toBe(
-        '<div><span class="chimay-leave-active chimay-leave-to" data-owl-key="__4__">blue</span></div>'
+        '<div><span class="chimay-leave-active chimay-leave-to" data-owl-key="4">blue</span></div>'
      );
      def.resolve();
    });
@@ -286,7 +283,7 @@ describe("animations", () => {
      }
    }

-    const widget = new Parent();
+    const widget = new Parent(env);
    await widget.mount(fixture);
    let button = widget.el!.querySelector("button");

@@ -323,23 +320,30 @@ describe("animations", () => {
  });

  test("t-transition combined with t-component, remove and re-add before transitionend", async () => {
-    expect.assertions(12);
+    expect.assertions(11);

-    class Child extends Widget {
-      static template = xml`<span>blue</span>`;
-    }
-    class Parent extends Widget {
-      static template = xml`
+    env.qweb.addTemplates(
+      `<templates>
        <div t-name="Parent">
+          <button t-on-click="toggle">Toggle</button>
          <t t-if="state.flag" t-component="Child" t-transition="chimay"/>
-        </div>`;
+        </div>
+        <span t-name="Child">blue</span>
+      </templates>`
+    );
+    class Child extends Widget {}
+    class Parent extends Widget {
      static components = { Child };
      state = useState({ flag: false });
+
+      toggle() {
+        this.state.flag = !this.state.flag;
+      }
    }

-    const widget = new Parent();
+    const widget = new Parent(env);
    await widget.mount(fixture);
-    expect(env.qweb.templates[Parent.template].fn.toString()).toMatchSnapshot();
+    let button = widget.el!.querySelector("button");

    let def = makeDeferred();
    let phase = "enter";
@@ -352,78 +356,24 @@ describe("animations", () => {
      def.resolve();
    });

-    // display the span
-    widget.state.flag = true;
+    // click display the span
+    button!.click();
    await def; // wait for the mocked repaint to be done
    widget.el!.querySelector("span")!.dispatchEvent(new Event("transitionend")); // mock end of css transition
-    expect(fixture.innerHTML).toBe('<div><span class="">blue</span></div>');
+    expect(fixture.innerHTML).toBe('<div><button>Toggle</button><span class="">blue</span></div>');

    // click to remove the span, and click again to re-add it before transitionend
    def = makeDeferred();
    phase = "leave";
-
-    widget.state.flag = false;
+    button!.click();

    await def; // wait for the mocked repaint to be done
    def = makeDeferred();
    phase = "enter";
-    widget.state.flag = true;
+    button!.click();

    await def; // wait for the mocked repaint to be done
    widget.el!.querySelector("span")!.dispatchEvent(new Event("transitionend")); // mock end of css transition
-    expect(fixture.innerHTML).toBe('<div><span class="" data-owl-key="__4__">blue</span></div>');
-  });
-
-  test("transitionInsert is called the correct amount of times", async () => {
-    const oldTransitionInsert = QWeb.utils.transitionInsert;
-    QWeb.utils.transitionInsert = jest.fn(oldTransitionInsert);
-
-    class Child extends Widget {
-      static template = xml`<span>blue</span>`;
-    }
-    class Parent extends Widget {
-      static template = xml`
-        <div t-name="Parent">
-          <Child t-if="state.flag" t-transition="chimay"/>
-        </div>`;
-      static components = { Child };
-      state = useState({ flag: false });
-    }
-
-    patchNextFrame(cb => cb());
-
-    const widget = new Parent();
-    await widget.mount(fixture);
-
-    widget.state.flag = true;
-
-    await nextTick();
-    widget.el!.querySelector("span")!.dispatchEvent(new Event("transitionend"));
-    expect(fixture.innerHTML).toBe('<div><span class="">blue</span></div>');
-    expect(QWeb.utils.transitionInsert).toBeCalledTimes(1);
-
-    widget.state.flag = false;
-    await nextTick();
-    expect(fixture.innerHTML).toBe(
-      '<div><span class="chimay-leave-active chimay-leave-to" data-owl-key="__4__">blue</span></div>'
-    );
-    expect(QWeb.utils.transitionInsert).toBeCalledTimes(1);
-
-    widget.state.flag = true;
-    await nextTick();
-    expect(fixture.innerHTML).toBe(
-      '<div><span class="chimay-enter-active chimay-enter-to" data-owl-key="__4__">blue</span></div>'
-    );
-    expect(QWeb.utils.transitionInsert).toBeCalledTimes(2);
-
-    widget.state.flag = false;
-    await nextTick();
-    widget.state.flag = true;
-    await nextTick();
-
-    expect(QWeb.utils.transitionInsert).toBeCalledTimes(3);
-    widget.el!.querySelector("span")!.dispatchEvent(new Event("transitionend"));
-    expect(fixture.innerHTML).toBe('<div><span class="" data-owl-key="__4__">blue</span></div>');
-    QWeb.utils.transitionInsert = oldTransitionInsert;
+    expect(fixture.innerHTML).toBe('<div><button>Toggle</button><span class="">blue</span></div>');
  });
 });
@@ -1,40 +1,49 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP

+exports[`default props default values are also set whenever component is updated 1`] = `"<div>1</div>"`;
+
+exports[`default props default values are also set whenever component is updated 2`] = `"<div>4</div>"`;
+
 exports[`props validation props are validated in dev mode (code snapshot) 1`] = `
-"function anonymous(context, extra
+"function anonymous(context,extra
 ) {
-    // Template name: \\"App\\"
    let utils = this.constructor.utils;
    let QWeb = this.constructor;
    let parent = context;
-    let scope = Object.create(context);
+    let owner = context;
    var h = this.h;
    let c1 = [], p1 = {key:1};
    var vn1 = h('div', p1, c1);
+    result = vn1;
    //COMPONENT
-    let k3 = \`__4__\`;
-    let w2 = k3 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[k3]] : false;
-    let props2 = {message:1};
-    if (w2 && w2.__owl__.currentFiber && !w2.__owl__.vnode) {
-        w2.destroy();
-        w2 = false;
+    let def3;
+    let w4 = 4 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[4]] : false;
+    let _2_index = c1.length;
+    c1.push(null);
+    let props4 = {message:1};
+    if (w4 && w4.__owl__.currentFiber && !w4.__owl__.vnode) {
+        if (utils.shallowEqual(props4, w4.__owl__.currentFiber.props)) {
+            def3 = w4.__owl__.currentFiber.promise;
+        } else {
+            w4.destroy();
+            w4 = false;
+        }
    }
-    if (w2) {
-        w2.__updateProps(props2, extra.fiber, undefined);
-        let pvnode = w2.__owl__.pvnode;
-        c1.push(pvnode);
+    if (!w4) {
+        let componentKey4 = \`Child\`;
+        let W4 = context.constructor.components[componentKey4] || QWeb.components[componentKey4]|| context['Child'];
+        if (!W4) {throw new Error('Cannot find the definition of component \\"' + componentKey4 + '\\"')}
+        utils.validateProps(W4, props4)
+        w4 = new W4(parent, props4);
+        parent.__owl__.cmap[4] = w4.__owl__.id;
+        def3 = w4.__prepare(extra.fiber, undefined, undefined);
+        def3 = def3.then(vnode=>{if (w4.__owl__.isDestroyed){return}let pvnode=h(vnode.sel, {key: 4, hook: {insert(vn) {let nvn=w4.__mount(vnode, pvnode.elm);pvnode.elm=nvn.elm;},remove() {},destroy(vn) {w4.destroy();}}});c1[_2_index]=pvnode;w4.__owl__.pvnode = pvnode;});
    } else {
-        let componentKey2 = \`Child\`;
-        let W2 = context.constructor.components[componentKey2] || QWeb.components[componentKey2]|| scope['Child'];
-        if (!W2) {throw new Error('Cannot find the definition of component \\"' + componentKey2 + '\\"')}
-        w2 = new W2(parent, props2);
-        parent.__owl__.cmap[k3] = w2.__owl__.id;
-        let fiber = w2.__prepare(extra.fiber, undefined, () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
-        let pvnode = h('dummy', {key: k3, hook: {remove() {},destroy(vn) {w2.destroy();}}});
-        c1.push(pvnode);
-        w2.__owl__.pvnode = pvnode;
+        utils.validateProps(w4.constructor, props4)
+        def3 = def3 || w4.__updateProps(props4, extra.fiber, undefined, undefined);
+        def3 = def3.then(()=>{if (w4.__owl__.isDestroyed) {return};let pvnode=w4.__owl__.pvnode;c1[_2_index]=pvnode;});
    }
-    w2.__owl__.parentLastFiberId = extra.fiber.id;
+    extra.promises.push(def3);
    return vn1;
 }"
 `;
@@ -1,8 +1,6 @@
 import { Component, Env } from "../../src/component/component";
-import { makeTestFixture, makeTestEnv, nextTick } from "../helpers";
-import { useState } from "../../src/hooks";
+import { makeTestFixture, makeTestEnv } from "../helpers";
 import { QWeb } from "../../src/qweb";
-import { xml } from "../../src/tags";

 //------------------------------------------------------------------------------
 // Setup and helpers
@@ -15,7 +13,6 @@ let dev: boolean = false;
 beforeEach(() => {
  fixture = makeTestFixture();
  env = makeTestEnv();
-  Component.env = env;
  dev = QWeb.dev;
  QWeb.dev = true;
 });
@@ -34,55 +31,28 @@ describe("props validation", () => {
  test("validation is only done in dev mode", async () => {
    class TestWidget extends Widget {
      static props = ["message"];
-      static template = xml`<div>hey</div>`;
-    }
-    class Parent extends Widget {
-      static components = { TestWidget };
-      static template = xml`<div><TestWidget /></div>`;
    }

-    let error;
    QWeb.dev = true;
-    try {
-      const p = new Parent();
-      await p.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeDefined();
-    expect(error.message).toBe(`Missing props 'message' (component 'TestWidget')`);
-
-    error = undefined;
+    expect(() => {
+      new TestWidget(env);
+    }).toThrow();

    QWeb.dev = false;
-    try {
-      const p = new Parent();
-      await p.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeUndefined();
+
+    expect(() => {
+      new TestWidget(env);
+    }).not.toThrow();
  });

  test("props: list of strings", async () => {
    class TestWidget extends Widget {
      static props = ["message"];
-      static template = xml`<div>hey</div>`;
-    }
-    class Parent extends Widget {
-      static components = { TestWidget };
-      static template = xml`<div><TestWidget /></div>`;
    }

-    let error;
-    try {
-      const p = new Parent();
-      await p.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeDefined();
-    expect(error.message).toBe(`Missing props 'message' (component 'TestWidget')`);
+    expect(() => {
+      new TestWidget(env);
+    }).toThrow("Missing props 'message' (component 'TestWidget')");
  });

  test("validate simple types", async () => {
@@ -95,50 +65,22 @@ describe("props validation", () => {
      { type: Function, ok: () => {}, ko: "1" }
    ];

-    let props;
-    class Parent extends Component<any, any> {
-      static template = xml`<div><TestWidget p="p"/></div>`;
-      get p() {
-        return props.p;
-      }
-    }
    for (let test of Tests) {
      let TestWidget = class extends Widget {
-        static template = xml`<div>hey</div>`;
        static props = { p: test.type };
      };
-      Parent.components = { TestWidget };

-      let error;
-      props = {};
-      try {
-        const p = new Parent();
-        await p.mount(fixture);
-      } catch (e) {
-        error = e;
-      }
-      expect(error).toBeDefined();
-      expect(error.message).toBe(`Missing props 'p' (component '_a')`);
+      expect(() => {
+        new TestWidget(env);
+      }).toThrow("Missing props 'p'");

-      error = undefined;
-      props = { p: test.ok };
-      try {
-        const p = new Parent();
-        await p.mount(fixture);
-      } catch (e) {
-        error = e;
-      }
-      expect(error).toBeUndefined();
+      expect(() => {
+        new TestWidget(env, { p: test.ok });
+      }).not.toThrow();

-      props = { p: test.ko };
-      try {
-        const p = new Parent();
-        await p.mount(fixture);
-      } catch (e) {
-        error = e;
-      }
-      expect(error).toBeDefined();
-      expect(error.message).toBe("Invalid Prop 'p' in component '_a'");
+      expect(() => {
+        new TestWidget(env, { p: test.ko });
+      }).toThrow("Props 'p' of invalid type in component");
    }
  });

@@ -152,307 +94,113 @@ describe("props validation", () => {
      { type: Function, ok: () => {}, ko: "1" }
    ];

-    let props;
-    class Parent extends Component<any, any> {
-      static template = xml`<div><TestWidget p="p"/></div>`;
-      get p() {
-        return props.p;
-      }
-    }
    for (let test of Tests) {
-      let TestWidget = class extends Component<any, any> {
+      let TestWidget = class extends Widget {
        static props = { p: { type: test.type } };
-        static template = xml`<div>hey</div>`;
      };
-      Parent.components = { TestWidget };

-      let error;
-      props = {};
-      try {
-        const p = new Parent();
-        await p.mount(fixture);
-      } catch (e) {
-        error = e;
-      }
-      expect(error).toBeDefined();
-      expect(error.message).toBe(`Missing props 'p' (component '_a')`);
+      expect(() => {
+        new TestWidget(env);
+      }).toThrow("Missing props 'p'");

-      error = undefined;
-      props = { p: test.ok };
-      try {
-        const p = new Parent();
-        await p.mount(fixture);
-      } catch (e) {
-        error = e;
-      }
-      expect(error).toBeUndefined();
+      expect(() => {
+        new TestWidget(env, { p: test.ok });
+      }).not.toThrow();

-      props = { p: test.ko };
-      try {
-        const p = new Parent();
-        await p.mount(fixture);
-      } catch (e) {
-        error = e;
-      }
-      expect(error).toBeDefined();
-      expect(error.message).toBe("Invalid Prop 'p' in component '_a'");
+      expect(() => {
+        new TestWidget(env, { p: test.ko });
+      }).toThrow("Props 'p' of invalid type in component");
    }
  });

  test("can validate a prop with multiple types", async () => {
-    class TestWidget extends Component<any, any> {
-      static template = xml`<div>hey</div>`;
+    let TestWidget = class extends Widget {
      static props = { p: [String, Boolean] };
-    }
-    class Parent extends Component<any, any> {
-      static template = xml`<div><TestWidget p="p"/></div>`;
-      static components = { TestWidget };
-      get p() {
-        return props.p;
-      }
-    }
+    };

-    let error;
-    let props;
-    try {
-      props = { p: "string" };
-      const p = new Parent();
-      await p.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeUndefined();
+    expect(() => {
+      new TestWidget(env, { p: "string" });
+      new TestWidget(env, { p: true });
+    }).not.toThrow();

-    try {
-      props = { p: true };
-      const p = new Parent();
-      await p.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeUndefined();
-
-    try {
-      props = { p: 1 };
-      const p = new Parent();
-      await p.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeDefined();
-    expect(error.message).toBe("Invalid Prop 'p' in component 'TestWidget'");
+    expect(() => {
+      new TestWidget(env, { p: 1 });
+    }).toThrow("Props 'p' of invalid type in component");
  });

  test("can validate an optional props", async () => {
-    class TestWidget extends Component<any, any> {
-      static template = xml`<div>hey</div>`;
+    let TestWidget = class extends Widget {
      static props = { p: { type: String, optional: true } };
-    }
-    class Parent extends Component<any, any> {
-      static template = xml`<div><TestWidget p="p"/></div>`;
-      static components = { TestWidget };
-      get p() {
-        return props.p;
-      }
-    }
+    };

-    let error;
-    let props;
-    try {
-      props = { p: "key" };
-      const p = new Parent();
-      await p.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeUndefined();
+    expect(() => {
+      new TestWidget(env, { p: "hey" });
+      new TestWidget(env, {});
+    }).not.toThrow();

-    try {
-      props = {};
-      const p = new Parent();
-      await p.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeUndefined();
-
-    try {
-      props = { p: 1 };
-      const p = new Parent();
-      await p.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeDefined();
-    expect(error.message).toBe("Invalid Prop 'p' in component 'TestWidget'");
+    expect(() => {
+      new TestWidget(env, { p: 1 });
+    }).toThrow();
  });

  test("can validate an array with given primitive type", async () => {
-    class TestWidget extends Component<any, any> {
-      static template = xml`<div>hey</div>`;
+    let TestWidget = class extends Widget {
      static props = { p: { type: Array, element: String } };
-    }
-    class Parent extends Component<any, any> {
-      static template = xml`<div><TestWidget p="p"/></div>`;
-      static components = { TestWidget };
-      get p() {
-        return props.p;
-      }
-    }
+    };

-    let error;
-    let props;
-    try {
-      props = { p: [] };
-      const p = new Parent();
-      await p.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeUndefined();
+    expect(() => {
+      new TestWidget(env, { p: [] });
+      new TestWidget(env, { p: ["string"] });
+    }).not.toThrow();

-    try {
-      props = { p: ["string"] };
-      const p = new Parent();
-      await p.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeUndefined();
+    expect(() => {
+      new TestWidget(env, { p: [1] });
+    }).toThrow();

-    try {
-      props = { p: [1] };
-      const p = new Parent();
-      await p.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeDefined();
-
-    error = undefined;
-    try {
-      props = { p: ["string", 1] };
-      const p = new Parent();
-      await p.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
+    expect(() => {
+      new TestWidget(env, { p: ["string", 1] });
+    }).toThrow();
  });

  test("can validate an array with multiple sub element types", async () => {
-    class TestWidget extends Component<any, any> {
-      static template = xml`<div>hey</div>`;
+    let TestWidget = class extends Widget {
      static props = { p: { type: Array, element: [String, Boolean] } };
-    }
-    class Parent extends Component<any, any> {
-      static template = xml`<div><TestWidget p="p"/></div>`;
-      static components = { TestWidget };
-      get p() {
-        return props.p;
-      }
-    }
+    };

-    let error;
-    let props;
-    try {
-      props = { p: [] };
-      const p = new Parent();
-      await p.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeUndefined();
+    expect(() => {
+      new TestWidget(env, { p: [] });
+      new TestWidget(env, { p: ["string"] });
+      new TestWidget(env, { p: [false, true, "string"] });
+    }).not.toThrow();

-    try {
-      props = { p: ["string"] };
-      const p = new Parent();
-      await p.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeUndefined();
-
-    try {
-      props = { p: [false, true, "string"] };
-      const p = new Parent();
-      await p.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeUndefined();
-
-    try {
-      props = { p: [true, 1] };
-      const p = new Parent();
-      await p.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeDefined();
-    expect(error.message).toBe("Invalid Prop 'p' in component 'TestWidget'");
+    expect(() => {
+      new TestWidget(env, { p: [true, 1] });
+    }).toThrow();
  });

  test("can validate an object with simple shape", async () => {
-    class TestWidget extends Component<any, any> {
-      static template = xml`<div>hey</div>`;
+    let TestWidget = class extends Widget {
      static props = {
        p: { type: Object, shape: { id: Number, url: String } }
      };
-    }
-    class Parent extends Component<any, any> {
-      static template = xml`<div><TestWidget p="p"/></div>`;
-      static components = { TestWidget };
-      get p() {
-        return props.p;
-      }
-    }
+    };

-    let error;
-    let props;
-    try {
-      props = { p: { id: 1, url: "url" } };
-      const p = new Parent();
-      await p.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeUndefined();
+    expect(() => {
+      new TestWidget(env, { p: { id: 1, url: "url" } });
+      new TestWidget(env, { p: { id: 1, url: "url", extra: true } });
+    }).not.toThrow();

-    try {
-      props = { p: { id: 1, url: "url", extra: true } };
-      const p = new Parent();
-      await p.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeDefined();
-    expect(error.message).toBe("Invalid prop 'p' in component TestWidget (unknown prop 'extra')");
+    expect(() => {
+      new TestWidget(env, { p: { id: "1", url: "url" } });
+    }).toThrow();

-    try {
-      props = { p: { id: "1", url: "url" } };
-      const p = new Parent();
-      await p.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeDefined();
-    expect(error.message).toBe("Invalid Prop 'p' in component 'TestWidget'");
-
-    error = undefined;
-    try {
-      props = { p: { id: 1 } };
-      const p = new Parent();
-      await p.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeDefined();
-    expect(error.message).toBe("Invalid Prop 'p' in component 'TestWidget'");
+    expect(() => {
+      new TestWidget(env, { p: { id: 1 } });
+    }).toThrow();
  });

  test("can validate recursively complicated prop def", async () => {
-    class TestWidget extends Component<any, any> {
-      static template = xml`<div>hey</div>`;
+    let TestWidget = class extends Widget {
      static props = {
        p: {
          type: Object,
@@ -462,141 +210,16 @@ describe("props validation", () => {
          }
        }
      };
-    }
-    class Parent extends Component<any, any> {
-      static template = xml`<div><TestWidget p="p"/></div>`;
-      static components = { TestWidget };
-      get p() {
-        return props.p;
-      }
-    }
+    };

-    let error;
-    let props;
-    try {
-      props = { p: { id: 1, url: true } };
-      const p = new Parent();
-      await p.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeUndefined();
+    expect(() => {
+      new TestWidget(env, { p: { id: 1, url: true } });
+      new TestWidget(env, { p: { id: 1, url: [12] } });
+    }).not.toThrow();

-    try {
-      props = { p: { id: 1, url: [12] } };
-      const p = new Parent();
-      await p.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeUndefined();
-
-    try {
-      props = { p: { id: 1, url: [12, true] } };
-      const p = new Parent();
-      await p.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeDefined();
-    expect(error.message).toBe("Invalid Prop 'p' in component 'TestWidget'");
-  });
-
-  test("can validate optional attributes in nested sub props", () => {
-    class TestComponent extends Component<any, any> {
-      static props = {
-        myprop: {
-          type: Array,
-          element: {
-            type: Object,
-            shape: {
-              num: { type: Number, optional: true }
-            }
-          }
-        }
-      };
-    }
-    let error;
-    try {
-      QWeb.utils.validateProps(TestComponent, { myprop: [{}] });
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeUndefined();
-
-    try {
-      QWeb.utils.validateProps(TestComponent, { myprop: [{ a: 1 }] });
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeDefined();
-    expect(error.message).toBe(
-      "Invalid prop 'myprop' in component TestComponent (unknown prop 'a')"
-    );
-  });
-
-  test("can validate with a custom validator", () => {
-    class TestComponent extends Component<any, any> {
-      static props = {
-        size: {
-          validate: e => ["small", "medium", "large"].includes(e)
-        }
-      };
-    }
-    let error;
-    try {
-      QWeb.utils.validateProps(TestComponent, { size: "small" });
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeUndefined();
-
-    try {
-      QWeb.utils.validateProps(TestComponent, { size: "abcdef" });
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeDefined();
-    expect(error.message).toBe("Invalid Prop 'size' in component 'TestComponent'");
-  });
-
-  test("can validate with a custom validator, and a type", () => {
-    const validator = jest.fn(n => 0 <= n && n <= 10);
-    class TestComponent extends Component<any, any> {
-      static props = {
-        n: {
-          type: Number,
-          validate: validator
-        }
-      };
-    }
-    let error;
-    try {
-      QWeb.utils.validateProps(TestComponent, { n: 3 });
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeUndefined();
-    expect(validator).toBeCalledTimes(1);
-
-    try {
-      QWeb.utils.validateProps(TestComponent, { n: "str" });
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeDefined();
-    expect(error.message).toBe("Invalid Prop 'n' in component 'TestComponent'");
-    expect(validator).toBeCalledTimes(1);
-
-    error = null;
-    try {
-      QWeb.utils.validateProps(TestComponent, { n: 100 });
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeDefined();
-    expect(error.message).toBe("Invalid Prop 'n' in component 'TestComponent'");
-    expect(validator).toBeCalledTimes(2);
+    expect(() => {
+      new TestWidget(env, { p: { id: 1, url: [12, true] } });
+    }).toThrow();
  });

  test("props are validated in dev mode (code snapshot)", async () => {
@@ -614,7 +237,7 @@ describe("props validation", () => {
    class App extends Widget {
      static components = { Child };
    }
-    const app = new App();
+    const app = new App(env);
    await app.mount(fixture);
    expect(fixture.innerHTML).toBe("<div><div>1</div></div>");
    // need to make sure there are 2 call to update props. one at component
@@ -645,32 +268,6 @@ describe("props validation", () => {
    }).toThrow();
  });

-  test("props with type array, and no element", async () => {
-    class TestWidget extends Widget {
-      static props = { myprop: { type: Array } };
-    }
-
-    expect(() => {
-      QWeb.utils.validateProps(TestWidget, { myprop: [1] });
-    }).not.toThrow();
-    expect(() => {
-      QWeb.utils.validateProps(TestWidget, { myprop: 1 });
-    }).toThrow(`Invalid Prop 'myprop' in component 'TestWidget'`);
-  });
-
-  test("props with type object, and no shape", async () => {
-    class TestWidget extends Widget {
-      static props = { myprop: { type: Object } };
-    }
-
-    expect(() => {
-      QWeb.utils.validateProps(TestWidget, { myprop: { a: 3 } });
-    }).not.toThrow();
-    expect(() => {
-      QWeb.utils.validateProps(TestWidget, { myprop: false });
-    }).toThrow(`Invalid Prop 'myprop' in component 'TestWidget'`);
-  });
-
  test("props: extra props cause an error", async () => {
    class TestWidget extends Widget {
      static props = ["message"];
@@ -713,131 +310,34 @@ describe("props validation", () => {
      QWeb.utils.validateProps(TestWidget, { message: null });
    }).toThrow();
  });
-
-  test("missing required boolean prop causes an error", async () => {
-    class TestWidget extends Widget {
-      static props = ["p"];
-      static template = xml`<span><t t-if="props.p">hey</t></span>`;
-    }
-
-    class App extends Widget {
-      static template = xml`<div><TestWidget/></div>`;
-      static components = { TestWidget };
-    }
-
-    const w = new App(undefined, {});
-    let error;
-    try {
-      await w.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeDefined();
-    expect(error.message).toBe("Missing props 'p' (component 'TestWidget')");
-  });
-
-  test("props are validated whenever component is updated", async () => {
-    let error;
-    class TestWidget extends Component<any, any> {
-      static props = { p: { type: Number } };
-      static template = xml`<div><t t-esc="props.p"/></div>`;
-
-      async __updateProps() {
-        try {
-          await Component.prototype.__updateProps.apply(this, arguments);
-        } catch (e) {
-          error = e;
-        }
-      }
-    }
-    class Parent extends Component<any, any> {
-      static template = xml`<div><TestWidget p="state.p"/></div>`;
-      static components = { TestWidget };
-      state: any = useState({ p: 1 });
-    }
-
-    const w = new Parent();
-    await w.mount(fixture);
-    expect(fixture.innerHTML).toBe("<div><div>1</div></div>");
-
-    w.state.p = undefined;
-    await nextTick();
-    expect(error).toBeDefined();
-    expect(error.message).toBe("Missing props 'p' (component 'TestWidget')");
-  });
-
-  test("default values are applied before validating props at update", async () => {
-    class TestWidget extends Component<any, any> {
-      static props = { p: { type: Number } };
-      static template = xml`<div><t t-esc="props.p"/></div>`;
-      static defaultProps = { p: 4 };
-    }
-    class Parent extends Component<any, any> {
-      static template = xml`<div><TestWidget p="state.p"/></div>`;
-      static components = { TestWidget };
-      state: any = useState({ p: 1 });
-    }
-
-    const w = new Parent();
-    await w.mount(fixture);
-    expect(fixture.innerHTML).toBe("<div><div>1</div></div>");
-
-    w.state.p = undefined;
-    await nextTick();
-    expect(fixture.innerHTML).toBe("<div><div>4</div></div>");
-  });
 });

 describe("default props", () => {
  test("can set default values", async () => {
-    class TestWidget extends Component<any, any> {
+    class TestWidget extends Widget {
      static defaultProps = { p: 4 };
-      static template = xml`<div><t t-esc="props.p"/></div>`;
-    }
-    class Parent extends Component<any, any> {
-      static template = xml`<div><TestWidget /></div>`;
-      static components = { TestWidget };
    }

-    const w = new Parent();
-    await w.mount(fixture);
-    expect(fixture.innerHTML).toBe("<div><div>4</div></div>");
+    const w = new TestWidget(env, {});
+    expect(w.props.p).toBe(4);
  });

  test("default values are also set whenever component is updated", async () => {
    class TestWidget extends Widget {
-      static template = xml`<div><t t-esc="props.p"/></div>`;
      static defaultProps = { p: 4 };
    }
-    class Parent extends Widget {
-      static template = xml`<div><TestWidget p="state.p"/></div>`;
-      static components = { TestWidget };
-      state: any = useState({ p: 1 });
-    }
+    env.qweb.addTemplates(`
+        <templates>
+            <div t-name="TestWidget"><t t-esc="props.p"/></div>
+        </templates>`);

-    const w = new Parent();
+    const w = new TestWidget(env, { p: 1 });
    await w.mount(fixture);
-    expect(fixture.innerHTML).toBe("<div><div>1</div></div>");
-
-    w.state.p = undefined;
-    await nextTick();
-    expect(fixture.innerHTML).toBe("<div><div>4</div></div>");
-  });
-
-  test("can set default required boolean values", async () => {
-    class TestWidget extends Widget {
-      static props = ["p", "q"];
-      static defaultProps = { p: true, q: false };
-      static template = xml`<span><t t-if="props.p">hey</t><t t-if="!props.q">hey</t></span>`;
-    }
-
-    class App extends Widget {
-      static template = xml`<div><TestWidget/></div>`;
-      static components = { TestWidget };
-    }
-
-    const w = new App(undefined, {});
-    await w.mount(fixture);
-    expect(fixture.innerHTML).toBe("<div><span>heyhey</span></div>");
+    expect(fixture.innerHTML).toMatchSnapshot();
+    const fiber = w.__createFiber(false, undefined, undefined, undefined);
+    await w.__updateProps({}, fiber);
+    await w.render();
+    expect(w.props.p).toBe(4);
+    expect(fixture.innerHTML).toMatchSnapshot();
  });
 });
@@ -1,339 +0,0 @@
-import { makeDeferred, makeTestEnv, makeTestFixture, nextTick } from "./helpers";
-import { Component } from "../src/component/component";
-import { Context, useContext } from "../src/context";
-import { xml } from "../src/tags";
-import { useState } from "../src/hooks";
-
-//------------------------------------------------------------------------------
-// Setup and helpers
-//------------------------------------------------------------------------------
-
-// We create before each test:
-// - fixture: a div, appended to the DOM, intended to be the target of dom
-//   manipulations.  Note that it is removed after each test.
-// - a test env, necessary to create components, that is set as env
-
-let fixture: HTMLElement;
-
-beforeEach(() => {
-  fixture = makeTestFixture();
-  Component.env = makeTestEnv();
-});
-
-afterEach(() => {
-  fixture.remove();
-});
-
-//------------------------------------------------------------------------------
-// Tests
-//------------------------------------------------------------------------------
-
-describe("Context", () => {
-  test("very simple use, with initial value", async () => {
-    const testContext = new Context({ value: 123 });
-
-    class Test extends Component<any, any> {
-      static template = xml`<div><t t-esc="contextObj.value"/></div>`;
-      contextObj = useContext(testContext);
-    }
-    const test = new Test();
-    await test.mount(fixture);
-    expect(fixture.innerHTML).toBe("<div>123</div>");
-  });
-
-  test("useContext hook is reactive, for one component", async () => {
-    const testContext = new Context({ value: 123 });
-
-    class Test extends Component<any, any> {
-      static template = xml`<div><t t-esc="contextObj.value"/></div>`;
-      contextObj = useContext(testContext);
-    }
-    const test = new Test();
-    await test.mount(fixture);
-    expect(fixture.innerHTML).toBe("<div>123</div>");
-    test.contextObj.value = 321;
-    await nextTick();
-    expect(fixture.innerHTML).toBe("<div>321</div>");
-  });
-
-  test("two components can subscribe to same context", async () => {
-    const testContext = new Context({ value: 123 });
-
-    class Child extends Component<any, any> {
-      static template = xml`<span><t t-esc="contextObj.value"/></span>`;
-      contextObj = useContext(testContext);
-    }
-    class Parent extends Component<any, any> {
-      static template = xml`<div><Child /><Child /></div>`;
-      static components = { Child };
-    }
-    const parent = new Parent();
-    await parent.mount(fixture);
-    expect(fixture.innerHTML).toBe("<div><span>123</span><span>123</span></div>");
-    testContext.state.value = 321;
-    await nextTick();
-    expect(fixture.innerHTML).toBe("<div><span>321</span><span>321</span></div>");
-  });
-
-  test("two async components are updated in parallel", async () => {
-    const testContext = new Context({ value: 123 });
-    const def = makeDeferred();
-    const steps: string[] = [];
-
-    class Child extends Component<any, any> {
-      static template = xml`<span><t t-esc="contextObj.value"/></span>`;
-      contextObj = useContext(testContext);
-      async render() {
-        steps.push("render");
-        await def;
-        return super.render();
-      }
-    }
-
-    class Parent extends Component<any, any> {
-      static template = xml`<div><Child /><Child /></div>`;
-      static components = { Child };
-    }
-    const parent = new Parent();
-    await parent.mount(fixture);
-    expect(fixture.innerHTML).toBe("<div><span>123</span><span>123</span></div>");
-    testContext.state.value = 321;
-    await nextTick();
-    expect(steps).toEqual(["render", "render"]);
-    expect(fixture.innerHTML).toBe("<div><span>123</span><span>123</span></div>");
-    def.resolve();
-    await nextTick();
-    expect(fixture.innerHTML).toBe("<div><span>321</span><span>321</span></div>");
-  });
-
-  test("two async components on two levels are updated (mostly) in parallel", async () => {
-    const testContext = new Context({ value: 123 });
-    const def = makeDeferred();
-    const steps: string[] = [];
-
-    class SlowComp extends Component<any, any> {
-      static template = xml`<p><t t-esc="props.value"/></p>`;
-      willUpdateProps() {
-        return def;
-      }
-    }
-    class Child extends Component<any, any> {
-      static template = xml`<span><SlowComp value="contextObj.value"/></span>`;
-      static components = { SlowComp };
-      contextObj = useContext(testContext);
-
-      render() {
-        steps.push("render");
-        return super.render();
-      }
-    }
-
-    class Parent extends Component<any, any> {
-      static template = xml`<div><Child /><Child /></div>`;
-      static components = { Child };
-    }
-
-    class App extends Component<any, any> {
-      static template = xml`<div><Child /><Parent /></div>`;
-      static components = { Child, Parent };
-    }
-
-    const app = new App();
-    await app.mount(fixture);
-    expect(fixture.innerHTML).toBe(
-      "<div><span><p>123</p></span><div><span><p>123</p></span><span><p>123</p></span></div></div>"
-    );
-    testContext.state.value = 321;
-    await nextTick();
-    expect(steps).toEqual(["render"]);
-    expect(fixture.innerHTML).toBe(
-      "<div><span><p>123</p></span><div><span><p>123</p></span><span><p>123</p></span></div></div>"
-    );
-    def.resolve();
-    await nextTick();
-    // we need to wait for an extra tick because it could happen (even though it
-    // is rare) that the second batch of renderings is not done yet, because
-    // the initial promise has been given to the macrotask queue, so a small
-    // delay happens.
-    await nextTick();
-    expect(steps).toEqual(["render", "render", "render"]);
-    expect(fixture.innerHTML).toBe(
-      "<div><span><p>321</p></span><div><span><p>321</p></span><span><p>321</p></span></div></div>"
-    );
-  });
-
-  test("one components can subscribe twice to same context", async () => {
-    const testContext = new Context({ a: 1, b: 2 });
-    const steps: string[] = [];
-
-    class Child extends Component<any, any> {
-      static template = xml`<span><t t-esc="contextObj1.a"/><t t-esc="contextObj2.b"/></span>`;
-      contextObj1 = useContext(testContext);
-      contextObj2 = useContext(testContext);
-      __render(fiber) {
-        steps.push("child");
-        return super.__render(fiber);
-      }
-    }
-    class Parent extends Component<any, any> {
-      static template = xml`<div><Child /></div>`;
-      static components = { Child };
-    }
-    const parent = new Parent();
-    await parent.mount(fixture);
-    expect(fixture.innerHTML).toBe("<div><span>12</span></div>");
-    expect(steps).toEqual(["child"]);
-    testContext.state.a = 3;
-    await nextTick();
-    expect(fixture.innerHTML).toBe("<div><span>32</span></div>");
-    expect(steps).toEqual(["child", "child"]);
-  });
-
-  test("parent and children subscribed to same context", async () => {
-    const testContext = new Context({ a: 123, b: 321 });
-    const steps: string[] = [];
-
-    class Child extends Component<any, any> {
-      static template = xml`<span><t t-esc="contextObj.a"/></span>`;
-      contextObj = useContext(testContext);
-      __render(fiber) {
-        steps.push("child");
-        return super.__render(fiber);
-      }
-    }
-    class Parent extends Component<any, any> {
-      static template = xml`<div><Child /><t t-esc="contextObj.b"/></div>`;
-      static components = { Child };
-      contextObj = useContext(testContext);
-      __render(fiber) {
-        steps.push("parent");
-        return super.__render(fiber);
-      }
-    }
-    const parent = new Parent();
-    await parent.mount(fixture);
-    expect(fixture.innerHTML).toBe("<div><span>123</span>321</div>");
-    expect(steps).toEqual(["parent", "child"]);
-
-    parent.contextObj.a = 124;
-    await nextTick();
-    expect(fixture.innerHTML).toBe("<div><span>124</span>321</div>");
-
-    // we only  want one render from the child here, not two
-    expect(steps).toEqual(["parent", "child", "parent", "child"]);
-  });
-
-  test("destroyed component is inactive", async () => {
-    const testContext = new Context({ a: 123 });
-    const steps: string[] = [];
-
-    class Child extends Component<any, any> {
-      static template = xml`<span><t t-esc="contextObj.a"/></span>`;
-      contextObj = useContext(testContext);
-      __render(fiber) {
-        steps.push("child");
-        return super.__render(fiber);
-      }
-    }
-    class Parent extends Component<any, any> {
-      static template = xml`<div><Child t-if="state.flag"/></div>`;
-      static components = { Child };
-      state = useState({ flag: true });
-      __render(fiber) {
-        steps.push("parent");
-        return super.__render(fiber);
-      }
-    }
-    const parent = new Parent();
-    await parent.mount(fixture);
-    expect(fixture.innerHTML).toBe("<div><span>123</span></div>");
-    expect(steps).toEqual(["parent", "child"]);
-    expect(testContext.subscriptions.update.length).toBe(1);
-
-    parent.state.flag = false;
-    await nextTick();
-    expect(fixture.innerHTML).toBe("<div></div>");
-    expect(steps).toEqual(["parent", "child", "parent"]);
-    // kind of whitebox...
-    // we make sure we do not have any pending subscriptions to the 'update'
-    // event
-    expect(testContext.subscriptions.update.length).toBe(0);
-  });
-
-  test("destroyed component before being mounted is inactive", async () => {
-    const testContext = new Context({ a: 123 });
-
-    class Child extends Component<any, any> {
-      static template = xml`<span><t t-esc="contextObj.a"/></span>`;
-      contextObj = useContext(testContext);
-      willStart() {
-        return makeDeferred();
-      }
-    }
-    class Parent extends Component<any, any> {
-      static template = xml`<div><Child t-if="state.flag"/></div>`;
-      static components = { Child };
-      state = useState({ flag: true });
-    }
-
-    const parent = new Parent();
-    const prom = parent.mount(fixture);
-    await nextTick(); // wait for Child to be instantiated
-    expect(testContext.subscriptions.update.length).toBe(1);
-    parent.state.flag = false;
-    await prom;
-    expect(fixture.innerHTML).toBe("<div></div>");
-    // kind of whitebox...
-    // we make sure we do not have any pending subscriptions to the 'update'
-    // event
-    expect(testContext.subscriptions.update.length).toBe(0);
-  });
-
-  test("concurrent renderings", async () => {
-    const testContext = new Context({ x: { n: 1 }, key: "x" });
-    const def = makeDeferred();
-    let stateC;
-    class ComponentC extends Component<any, any> {
-      static template = xml`<span><t t-esc="context[props.key].n"/><t t-esc="state.x"/></span>`;
-      context = useContext(testContext);
-      state = useState({ x: "a" });
-
-      constructor(parent, props) {
-        super(parent, props);
-        stateC = this.state;
-      }
-    }
-    class ComponentB extends Component<any, any> {
-      static components = { ComponentC };
-      static template = xml`<p><ComponentC key="props.key"/></p>`;
-
-      willUpdateProps() {
-        return def;
-      }
-    }
-    class ComponentA extends Component<any, any> {
-      static components = { ComponentB };
-      static template = xml`<div><ComponentB key="context.key"/></div>`;
-      context = useContext(testContext);
-    }
-
-    const component = new ComponentA();
-    await component.mount(fixture);
-
-    expect(fixture.innerHTML).toBe("<div><p><span>1a</span></p></div>");
-    testContext.state.key = "y";
-    testContext.state.y = { n: 2 };
-    delete testContext.state.x;
-    await nextTick();
-
-    expect(fixture.innerHTML).toBe("<div><p><span>1a</span></p></div>");
-    stateC.x = "b";
-    await nextTick();
-
-    expect(fixture.innerHTML).toBe("<div><p><span>1a</span></p></div>");
-    def.resolve();
-    await nextTick();
-
-    expect(fixture.innerHTML).toBe("<div><p><span>2b</span></p></div>");
-  });
-});
@@ -8,11 +8,13 @@ describe("observer", () => {

    expect(typeof obj).toBe("object");
    expect(observer.revNumber(obj)).toBe(1);
+    expect(observer.deepRevNumber(obj)).toBe(1);
    expect(observer.rev).toBe(1);

    const obj2: any = observer.observe({ a: 1 });
    expect(observer.revNumber(obj2)).toBe(1);
    expect(observer.revNumber(obj)).toBe(1);
+    expect(observer.deepRevNumber(obj)).toBe(1);
    expect(observer.rev).toBe(1);

    obj2.a = 2;
@@ -31,19 +33,23 @@ describe("observer", () => {
    const obj: any = observer.observe({ a: null, b: undefined });

    expect(observer.revNumber(obj)).toBe(1);
+    expect(observer.deepRevNumber(obj)).toBe(1);
    expect(observer.rev).toBe(1);

    obj.a = 3;
    expect(observer.revNumber(obj)).toBe(2);
+    expect(observer.deepRevNumber(obj)).toBe(2);
    expect(observer.rev).toBe(2);

    obj.b = 5;
    expect(observer.revNumber(obj)).toBe(3);
+    expect(observer.deepRevNumber(obj)).toBe(3);
    expect(observer.rev).toBe(3);

    obj.a = null;
    obj.b = undefined;
    expect(observer.revNumber(obj)).toBe(5);
+    expect(observer.deepRevNumber(obj)).toBe(5);
    expect(observer.rev).toBe(5);
    expect(obj).toEqual({
      a: null,
@@ -57,6 +63,7 @@ describe("observer", () => {
    const obj: any = observer.observe({ date });

    expect(observer.revNumber(obj)).toBe(1);
+    expect(observer.deepRevNumber(obj)).toBe(1);
    expect(observer.rev).toBe(1);
    expect(typeof obj.date.getFullYear()).toBe("number");
    expect(obj.date).toBe(date);
@@ -64,6 +71,7 @@ describe("observer", () => {
    obj.date = new Date();

    expect(observer.revNumber(obj)).toBe(2);
+    expect(observer.deepRevNumber(obj)).toBe(2);
    expect(observer.rev).toBe(2);
    expect(obj.date).not.toBe(date);
  });
@@ -74,11 +82,14 @@ describe("observer", () => {

    expect(Array.isArray(obj.arr)).toBe(true);
    expect(observer.revNumber(obj.arr)).toBe(1);
+    expect(observer.deepRevNumber(obj.arr)).toBe(1);
    expect(observer.rev).toBe(1);

    obj.arr[0] = "nope";
    expect(observer.revNumber(obj.arr)).toBe(2);
-    expect(observer.revNumber(obj)).toBe(2);
+    expect(observer.deepRevNumber(obj.arr)).toBe(2);
+    expect(observer.revNumber(obj)).toBe(1);
+    expect(observer.deepRevNumber(obj)).toBe(2);
    expect(observer.rev).toBe(2);
  });

@@ -87,20 +98,24 @@ describe("observer", () => {
    const obj: any = observer.observe({ a: 1 });

    expect(observer.revNumber(obj)).toBe(1);
+    expect(observer.deepRevNumber(obj)).toBe(1);
    expect(observer.rev).toBe(1);

    obj.a = 2;

    expect(observer.revNumber(obj)).toBe(2);
+    expect(observer.deepRevNumber(obj)).toBe(2);
    expect(observer.rev).toBe(2);

    // same value again
    obj.a = 2;
    expect(observer.revNumber(obj)).toBe(2);
+    expect(observer.deepRevNumber(obj)).toBe(2);
    expect(observer.rev).toBe(2);

    obj.a = 3;
    expect(observer.revNumber(obj)).toBe(3);
+    expect(observer.deepRevNumber(obj)).toBe(3);
    expect(observer.rev).toBe(3);
  });

@@ -111,16 +126,19 @@ describe("observer", () => {
    expect(Array.isArray(arr)).toBe(true);
    expect(arr.length).toBe(0);
    expect(observer.revNumber(arr)).toBe(1);
+    expect(observer.deepRevNumber(arr)).toBe(1);
    expect(observer.rev).toBe(1);

    arr.push(1);
    expect(observer.revNumber(arr)).toBe(2);
+    expect(observer.deepRevNumber(arr)).toBe(2);
    expect(observer.rev).toBe(2);
    expect(arr.length).toBe(1);
    expect(arr).toEqual([1]);

    arr.splice(1, 0, "hey");
    expect(observer.revNumber(arr)).toBe(3);
+    expect(observer.deepRevNumber(arr)).toBe(3);
    expect(observer.rev).toBe(3);
    expect(arr).toEqual([1, "hey"]);
    expect(arr.length).toBe(2);
@@ -128,6 +146,7 @@ describe("observer", () => {
    arr.unshift("lindemans");
    //it generates 3 primitive operations
    expect(observer.revNumber(arr)).toBe(6);
+    expect(observer.deepRevNumber(arr)).toBe(6);
    expect(observer.rev).toBe(6);
    expect(arr).toEqual(["lindemans", 1, "hey"]);
    expect(arr.length).toBe(3);
@@ -135,18 +154,21 @@ describe("observer", () => {
    arr.reverse();
    //it generates 2 primitive operations
    expect(observer.revNumber(arr)).toBe(8);
+    expect(observer.deepRevNumber(arr)).toBe(8);
    expect(observer.rev).toBe(8);
    expect(arr).toEqual(["hey", 1, "lindemans"]);
    expect(arr.length).toBe(3);

    arr.pop(); // one set, one delete
    expect(observer.revNumber(arr)).toBe(10);
+    expect(observer.deepRevNumber(arr)).toBe(10);
    expect(observer.rev).toBe(10);
    expect(arr).toEqual(["hey", 1]);
    expect(arr.length).toBe(2);

    arr.shift(); // 2 sets, 1 delete
    expect(observer.revNumber(arr)).toBe(13);
+    expect(observer.deepRevNumber(arr)).toBe(13);
    expect(observer.rev).toBe(13);
    expect(arr).toEqual([1]);
    expect(arr.length).toBe(1);
@@ -165,7 +187,8 @@ describe("observer", () => {
    arr[0].kriek = 6;

    expect(observer.rev).toBe(3);
-    expect(observer.revNumber(arr)).toBe(3);
+    expect(observer.revNumber(arr)).toBe(2);
+    expect(observer.deepRevNumber(arr)).toBe(3);
    expect(observer.revNumber(arr[0])).toBe(3);
  });

@@ -215,6 +238,7 @@ describe("observer", () => {

    expect(observer.rev).toBe(1);
    expect(observer.revNumber(state)).toBe(1);
+    expect(observer.deepRevNumber(state)).toBe(1);
    expect(observer.notifyCB).toBeCalledTimes(0);

    state[1] = "b";
@@ -223,6 +247,7 @@ describe("observer", () => {

    expect(observer.rev).toBe(2);
    expect(observer.revNumber(state)).toBe(2);
+    expect(observer.deepRevNumber(state)).toBe(2);
    expect(observer.notifyCB).toBeCalledTimes(1);

    expect(state).toEqual(["a", "b"]);
@@ -234,11 +259,13 @@ describe("observer", () => {

    expect(observer.rev).toBe(1);
    expect(observer.revNumber(state.arr)).toBe(1);
+    expect(observer.deepRevNumber(state.arr)).toBe(1);
    expect(state.arr.length).toBe(0);

    state.arr.push(1);
    expect(observer.rev).toBe(2);
    expect(observer.revNumber(state.arr)).toBe(2);
+    expect(observer.deepRevNumber(state.arr)).toBe(2);
    expect(state.arr.length).toBe(1);
  });

@@ -253,7 +280,7 @@ describe("observer", () => {

    state.arr[0].something = 2;
    expect(observer.rev).toBe(2);
-    expect(observer.revNumber(state.arr)).toBe(2);
+    expect(observer.revNumber(state.arr)).toBe(1);
    expect(observer.revNumber(state.arr[0])).toBe(2);
  });

@@ -267,7 +294,7 @@ describe("observer", () => {

    state.a.b = 2;
    expect(observer.rev).toBe(2);
-    expect(observer.revNumber(state)).toBe(2);
+    expect(observer.revNumber(state)).toBe(1);
    expect(observer.revNumber(state.a)).toBe(2);
  });

@@ -285,7 +312,7 @@ describe("observer", () => {
    expect(observer.revNumber(obj.a)).toBe(2);
    obj.a.b = 3;
    expect(observer.rev).toBe(3);
-    expect(observer.revNumber(obj)).toBe(3);
+    expect(observer.revNumber(obj)).toBe(2);
    expect(observer.revNumber(obj.a)).toBe(3);
  });

@@ -293,18 +320,22 @@ describe("observer", () => {
    const observer = new Observer();
    const state: any = observer.observe({ o: { a: 1 }, arr: [1], n: 13 });
    expect(observer.revNumber(state)).toBe(1);
+    expect(observer.deepRevNumber(state)).toBe(1);

    state.o.a = 2;
    expect(observer.rev).toBe(2);
-    expect(observer.revNumber(state)).toBe(2);
+    expect(observer.revNumber(state)).toBe(1);
+    expect(observer.deepRevNumber(state)).toBe(2);

    state.arr.push(2);
    expect(observer.rev).toBe(3);
-    expect(observer.revNumber(state)).toBe(3);
+    expect(observer.revNumber(state)).toBe(1);
+    expect(observer.deepRevNumber(state)).toBe(3);

    state.n = 155;
    expect(observer.rev).toBe(4);
-    expect(observer.revNumber(state)).toBe(4);
+    expect(observer.revNumber(state)).toBe(2);
+    expect(observer.deepRevNumber(state)).toBe(4);
  });

  test("properly handle already observed state", () => {
@@ -330,15 +361,18 @@ describe("observer", () => {
    const obj: any = observer.observe({});

    expect(observer.revNumber(obj)).toBe(1);
+    expect(observer.deepRevNumber(obj)).toBe(1);
    expect(observer.rev).toBe(1);

    obj.aku = "always finds annoying problems";
    expect(observer.revNumber(obj)).toBe(2);
+    expect(observer.deepRevNumber(obj)).toBe(2);
    expect(observer.rev).toBe(2);

    obj.aku = "always finds good problems";

    expect(observer.revNumber(obj)).toBe(3);
+    expect(observer.deepRevNumber(obj)).toBe(3);
    expect(observer.rev).toBe(3);
  });

@@ -382,7 +416,7 @@ describe("observer", () => {
    expect(observer.revNumber(obj2)).toBe(1);

    obj2.key = 3;
-    expect(observer.revNumber(obj1)).toBe(2);
+    expect(observer.revNumber(obj1)).toBe(1);
    expect(observer.revNumber(obj2)).toBe(2);
  });

@@ -408,7 +442,7 @@ describe("observer", () => {
    obj.a = 111;
    obj.f = 222;
    await nextMicroTick();
-    expect(observer.notifyCB).toBeCalledTimes(5);
+    expect(observer.notifyCB).toBeCalledTimes(4);
  });

  test("throw error when state is mutated in object if allowMutation=false", async () => {
@@ -0,0 +1,126 @@
+/**
+ * Doc Link Checker
+ *
+ * We define here a test to make sure that there are no dead link in the Owl
+ * documentation.
+ */
+import * as fs from "fs";
+
+const LINK_REGEXP = /\[([^\[]+)\]\(([^\)]+)\)/g;
+const HEADING_REGEXP = /\n(#+\s*)(.*)/g;
+
+// files to be checked
+function getFiles(): string[] {
+  const DOCFILES = fs.readdirSync("doc").map(f => `doc/${f}`);
+  const MAINREADME = "README.md";
+  return DOCFILES.concat(MAINREADME);
+}
+
+test("All markdown links work", () => {
+  let linkNumber = 0;
+  let invalidLinkNumber = 0;
+  const files = getFiles();
+  const data = readDocData(files);
+  for (let file of data) {
+    for (let link of file.links) {
+      // DEBUG: uncomment next line
+      // console.warn(`Checking "${link.name}" in "${file.name}"`);
+      linkNumber++;
+      if (!isLinkValid(link, file, data)) {
+        console.warn(`Invalid Link: "${link.name}" in "${file.name}"`);
+        invalidLinkNumber++;
+      }
+    }
+  }
+  expect(invalidLinkNumber).toBe(0);
+  expect(linkNumber).toBeGreaterThan(10);
+});
+
+interface MarkDownLink {
+  name: string;
+  link: string;
+}
+
+interface MarkDownSection {
+  name: string;
+  slug: string;
+}
+
+interface FileData {
+  name: string;
+  links: MarkDownLink[];
+  sections: MarkDownSection[];
+}
+
+function isLinkValid(link: MarkDownLink, current: FileData, files: FileData[]): boolean {
+  const parts = link.link.split("#");
+  const currentParts = current.name.split("/");
+  const path = currentParts.length > 1 ? currentParts[0] + "/" : "";
+  const fullName = path + parts[0];
+  if (parts.length === 1) {
+    // no # in url
+    if (parts[0].endsWith(".md")) {
+      // it is a local md file
+      if (!files.find(f => f.name === fullName)) {
+        return false;
+      }
+    }
+  } else {
+    const file = parts[0] === "" ? current : files.find(f => f.name === fullName);
+    if (!file) {
+      return false;
+    }
+    if (!file.sections.find(s => s.slug === parts[1])) {
+      return false;
+    }
+  }
+  return true;
+}
+// adapted from https://medium.com/@mhagemann/the-ultimate-way-to-slugify-a-url-string-in-javascript-b8e4a0d849e1
+function slugify(str) {
+  const a = "àáäâãåăæçèéëêǵḧìíïîḿńǹñòóöôœøṕŕßśșțùúüûǘẃẍÿź·_,:;";
+  const b = "aaaaaaaaceeeeghiiiimnnnooooooprssstuuuuuwxyz-----";
+  const p = new RegExp(a.split("").join("|"), "g");
+  return str
+    .toString()
+    .toLowerCase()
+    .replace(/\//g, "") // remove /
+    .replace(/\s+/g, "-") // Replace spaces with -
+    .replace(p, c => b.charAt(a.indexOf(c))) // Replace special characters
+    .replace(/&/g, "-and-") // Replace & with ‘and’
+    .replace(/[^\w\-]+/g, "") // Remove all non-word characters
+    .replace(/\-\-+/g, "-") // Replace multiple - with single -
+    .replace(/^-+/, "") // Trim - from start of text
+    .replace(/-+$/, ""); // Trim - from end of text
+}
+
+function readDocData(files: string[]): FileData[] {
+  const result: FileData[] = [];
+
+  for (let file of files) {
+    const fileData: FileData = {
+      name: file,
+      links: [],
+      sections: []
+    };
+    const content = fs.readFileSync(file, { encoding: "utf8" });
+    let m;
+    // get links info
+    do {
+      m = LINK_REGEXP.exec(content);
+      if (m) {
+        fileData.links.push({ name: m[0], link: m[2] });
+      }
+    } while (m);
+    // get sections info
+    do {
+      m = HEADING_REGEXP.exec(content);
+      if (m) {
+        fileData.sections.push({ name: m[0], slug: slugify(m[2]) });
+      }
+    } while (m);
+
+    result.push(fileData);
+  }
+  return result;
+}
@@ -1,18 +1,10 @@
 import { Env } from "../src/component/component";
-import { scheduler } from "../src/component/scheduler";
 import { EvalContext, QWeb } from "../src/qweb/qweb";
-import { CompilationContext } from "../src/qweb/compilation_context";
 import { patch } from "../src/vdom";
 import "../src/qweb/base_directives";
 import "../src/qweb/extensions";
 import "../src/component/directive";

-// modifies scheduler to make it faster to test components
-scheduler.requestAnimationFrame = function(callback: FrameRequestCallback) {
-  setTimeout(callback, 1);
-  return 1;
-};
-
 // Some static cleanup
 let nextSlotId;
 let slots;
@@ -21,7 +13,6 @@ let TEMPLATES;

 beforeEach(() => {
  nextSlotId = QWeb.nextSlotId;
-  CompilationContext.nextID = 1;
  slots = Object.assign({}, QWeb.slots);
  nextId = QWeb.nextId;
  TEMPLATES = Object.assign({}, QWeb.TEMPLATES);
@@ -39,10 +30,8 @@ export function nextMicroTick(): Promise<void> {
  return Promise.resolve();
 }

-export async function nextTick(): Promise<void> {
-  return new Promise(function(resolve) {
-    setTimeout(() => scheduler.requestAnimationFrame(() => resolve()));
-  });
+export function nextTick(): Promise<void> {
+  return new Promise(resolve => setTimeout(resolve));
 }

 export function makeTestFixture() {
@@ -87,11 +76,6 @@ export function renderToDOM(
  context: EvalContext = {},
  extra?: any
 ): HTMLElement | Text {
-  if (!context.__owl__) {
-    // we add `__owl__` to better simulate a component as context.  This is
-    // particularly important for event handlers added with the `t-on` directive.
-    context.__owl__ = { isMounted: true };
-  }
  const vnode = qweb.render(template, context, extra);

  // we snapshot here the compiled code. This is useful to prevent unwanted code
@@ -7,8 +7,6 @@ import {
  useRef,
  onPatched,
  onWillPatch,
-  onWillStart,
-  onWillUpdateProps,
  useSubEnv
 } from "../src/hooks";
 import { xml } from "../src/tags";
@@ -28,7 +26,6 @@ let env: Env;
 beforeEach(() => {
  fixture = makeTestFixture();
  env = makeTestEnv();
-  Component.env = env;
 });

 afterEach(() => {
@@ -45,7 +42,7 @@ describe("hooks", () => {
      static template = xml`<div><t t-esc="counter.value"/></div>`;
      counter = useState({ value: 42 });
    }
-    const counter = new Counter();
+    const counter = new Counter(env);
    await counter.mount(fixture);
    expect(fixture.innerHTML).toBe("<div>42</div>");
    counter.counter.value = 3;
@@ -65,12 +62,12 @@ describe("hooks", () => {
    }
    class MyComponent extends Component<any, any> {
      static template = xml`<div>hey</div>`;
-      constructor() {
-        super();
+      constructor(env) {
+        super(env);
        useMyHook();
      }
    }
-    const component = new MyComponent();
+    const component = new MyComponent(env);
    await component.mount(fixture);
    expect(component).not.toHaveProperty("mounted");
    expect(component).not.toHaveProperty("willUnmount");
@@ -81,40 +78,6 @@ describe("hooks", () => {
    expect(steps).toEqual(["mounted", "willunmount"]);
  });

-  test("can use onMounted, onWillUnmount, part 2", async () => {
-    const steps: string[] = [];
-    function useMyHook() {
-      onMounted(() => {
-        steps.push("mounted");
-      });
-      onWillUnmount(() => {
-        steps.push("willunmount");
-      });
-    }
-    class MyComponent extends Component<any, any> {
-      static template = xml`<div>hey</div>`;
-      constructor(parent, props) {
-        super(parent, props);
-        useMyHook();
-      }
-    }
-
-    class Parent extends Component<any, any> {
-      static template = xml`<div><MyComponent t-if="state.flag"/></div>`;
-      static components = { MyComponent };
-      state = useState({ flag: true });
-    }
-    const parent = new Parent();
-    await parent.mount(fixture);
-    expect(fixture.innerHTML).toBe("<div><div>hey</div></div>");
-    expect(steps).toEqual(["mounted"]);
-
-    parent.state.flag = false;
-    await nextTick();
-    expect(fixture.innerHTML).toBe("<div></div>");
-    expect(steps).toEqual(["mounted", "willunmount"]);
-  });
-
  test("mounted, willUnmount, onMounted, onWillUnmount order", async () => {
    const steps: string[] = [];
    function useMyHook() {
@@ -127,8 +90,8 @@ describe("hooks", () => {
    }
    class MyComponent extends Component<any, any> {
      static template = xml`<div>hey</div>`;
-      constructor() {
-        super();
+      constructor(env) {
+        super(env);
        useMyHook();
      }
      mounted() {
@@ -138,7 +101,7 @@ describe("hooks", () => {
        steps.push("comp:willunmount");
      }
    }
-    const component = new MyComponent();
+    const component = new MyComponent(env);
    await component.mount(fixture);
    expect(fixture.innerHTML).toBe("<div>hey</div>");
    component.unmount();
@@ -146,46 +109,6 @@ describe("hooks", () => {
    expect(steps).toEqual(["comp:mounted", "hook:mounted", "hook:willunmount", "comp:willunmount"]);
  });

-  test("mounted, willUnmount, onMounted, onWillUnmount order, part 2", async () => {
-    const steps: string[] = [];
-    function useMyHook() {
-      onMounted(() => {
-        steps.push("hook:mounted");
-      });
-      onWillUnmount(() => {
-        steps.push("hook:willunmount");
-      });
-    }
-    class MyComponent extends Component<any, any> {
-      static template = xml`<div>hey</div>`;
-      constructor(parent, props) {
-        super(parent, props);
-        useMyHook();
-      }
-      mounted() {
-        steps.push("comp:mounted");
-      }
-      willUnmount() {
-        steps.push("comp:willunmount");
-      }
-    }
-
-    class Parent extends Component<any, any> {
-      static template = xml`<div><MyComponent t-if="state.flag"/></div>`;
-      static components = { MyComponent };
-      state = useState({ flag: true });
-    }
-
-    const parent = new Parent();
-    await parent.mount(fixture);
-    expect(fixture.innerHTML).toBe("<div><div>hey</div></div>");
-    parent.state.flag = false;
-    await nextTick();
-    expect(fixture.innerHTML).toBe("<div></div>");
-
-    expect(steps).toEqual(["comp:mounted", "hook:mounted", "hook:willunmount", "comp:willunmount"]);
-  });
-
  test("two different call to mounted/willunmount should work", async () => {
    const steps: string[] = [];
    function useMyHook(i) {
@@ -198,13 +121,13 @@ describe("hooks", () => {
    }
    class MyComponent extends Component<any, any> {
      static template = xml`<div>hey</div>`;
-      constructor() {
-        super();
+      constructor(env) {
+        super(env);
        useMyHook(1);
        useMyHook(2);
      }
    }
-    const component = new MyComponent();
+    const component = new MyComponent(env);
    await component.mount(fixture);
    expect(fixture.innerHTML).toBe("<div>hey</div>");
    component.unmount();
@@ -227,136 +150,14 @@ describe("hooks", () => {
        (this.button.el as HTMLButtonElement).innerHTML = String(this.value);
      }
    }
-    const counter = new Counter();
-    expect(counter.button.el).toBe(null);
+    const counter = new Counter(env);
    await counter.mount(fixture);
    expect(fixture.innerHTML).toBe("<div><button>0</button></div>");
-    expect(counter.button.el).not.toBe(null);
-    expect(counter.button.el).toBe(fixture.querySelector("button"));
    counter.increment();
    await nextTick();
    expect(fixture.innerHTML).toBe("<div><button>1</button></div>");
  });

-  test("useRef hook is null if ref is removed ", async () => {
-    expect.assertions(4);
-    class TestRef extends Component<any, any> {
-      static template = xml`<div><span t-if="state.flag" t-ref="span">owl</span></div>`;
-      spanRef = useRef("span");
-      state = useState({ flag: true });
-      willPatch() {
-        expect(this.spanRef.el).not.toBeNull();
-      }
-      patched() {
-        expect(this.spanRef.el).toBeNull();
-      }
-    }
-    const component = new TestRef();
-    await component.mount(fixture);
-    expect(fixture.innerHTML).toBe("<div><span>owl</span></div>");
-    component.state.flag = false;
-    await nextTick();
-    expect(fixture.innerHTML).toBe("<div></div>");
-  });
-
-  test("t-refs on widget are components", async () => {
-    class WidgetB extends Component<any, any> {
-      static template = xml`<div>b</div>`;
-    }
-    class WidgetC extends Component<any, any> {
-      static template = xml`<div class="outer-div">Hello<WidgetB t-ref="mywidgetb" /></div>`;
-      static components = { WidgetB };
-      ref = useRef("mywidgetb");
-    }
-
-    const widget = new WidgetC();
-    expect(widget.ref.comp).toBe(null);
-    expect(widget.ref.el).toBe(null);
-    await widget.mount(fixture);
-    expect(widget.ref.comp).toBeInstanceOf(WidgetB);
-    expect(widget.ref.el).toEqual(fixture.querySelector(".outer-div > div"));
-  });
-
-  test("t-refs are bound at proper timing", async () => {
-    expect.assertions(2);
-    class Widget extends Component<any, any> {
-      static template = xml`<div>widget</div>`;
-    }
-
-    class ParentWidget extends Component<any, any> {
-      static template = xml`
-        <div>
-          <t t-foreach="state.list" t-as="elem" t-ref="child" t-key="elem" t-component="Widget"/>
-        </div>
-      `;
-      static components = { Widget };
-      state = useState({ list: <any>[] });
-      child = useRef("child");
-      willPatch() {
-        expect(this.child.comp).toBeNull();
-      }
-      patched() {
-        expect(this.child.comp).not.toBeNull();
-      }
-    }
-
-    const parent = new ParentWidget();
-    await parent.mount(fixture);
-    parent.state.list.push(1);
-    await nextTick();
-  });
-
-  test("t-refs are bound at proper timing (2)", async () => {
-    expect.assertions(10);
-    class Widget extends Component<any, any> {
-      static template = xml`<div>widget</div>`;
-    }
-    class ParentWidget extends Component<any, any> {
-      static template = xml`
-        <div>
-          <t t-if="state.child1" t-ref="child1" t-component="Widget"/>
-          <t t-if="state.child2" t-ref="child2" t-component="Widget"/>
-        </div>`;
-      static components = { Widget };
-      state = useState({ child1: true, child2: false });
-      child1 = useRef("child1");
-      child2 = useRef("child2");
-      count = 0;
-      mounted() {
-        expect(this.child1.comp).toBeDefined();
-        expect(this.child2.comp).toBeNull();
-      }
-      willPatch() {
-        if (this.count === 0) {
-          expect(this.child1.comp).toBeDefined();
-          expect(this.child2.comp).toBeNull();
-        }
-        if (this.count === 1) {
-          expect(this.child1.comp).toBeDefined();
-          expect(this.child2.comp).toBeDefined();
-        }
-      }
-      patched() {
-        if (this.count === 0) {
-          expect(this.child1.comp).toBeDefined();
-          expect(this.child2.comp).toBeDefined();
-        }
-        if (this.count === 1) {
-          expect(this.child1.comp).toBeNull();
-          expect(this.child2.comp).toBeDefined();
-        }
-        this.count++;
-      }
-    }
-
-    const parent = new ParentWidget();
-    await parent.mount(fixture);
-    parent.state.child2 = true;
-    await nextTick();
-    parent.state.child1 = false;
-    await nextTick();
-  });
-
  test("can use onPatched, onWillPatch", async () => {
    const steps: string[] = [];
    function useMyHook() {
@@ -372,13 +173,13 @@ describe("hooks", () => {
      static template = xml`<div><t t-if="state.flag">hey</t></div>`;
      state = useState({ flag: true });

-      constructor() {
-        super();
+      constructor(env) {
+        super(env);
        useMyHook();
      }
    }

-    const component = new MyComponent();
+    const component = new MyComponent(env);
    await component.mount(fixture);
    expect(component).not.toHaveProperty("patched");
    expect(component).not.toHaveProperty("willPatch");
@@ -406,8 +207,8 @@ describe("hooks", () => {
      static template = xml`<div><t t-if="state.flag">hey</t></div>`;
      state = useState({ flag: true });

-      constructor() {
-        super();
+      constructor(env) {
+        super(env);
        useMyHook();
      }
      willPatch() {
@@ -417,7 +218,7 @@ describe("hooks", () => {
        steps.push("comp:patched");
      }
    }
-    const component = new MyComponent();
+    const component = new MyComponent(env);
    await component.mount(fixture);
    expect(fixture.innerHTML).toBe("<div>hey</div>");
    component.state.flag = false;
@@ -439,13 +240,13 @@ describe("hooks", () => {
    class MyComponent extends Component<any, any> {
      static template = xml`<div>hey<t t-esc="state.value"/></div>`;
      state = useState({ value: 1 });
-      constructor() {
-        super();
+      constructor(env) {
+        super(env);
        useMyHook(1);
        useMyHook(2);
      }
    }
-    const component = new MyComponent();
+    const component = new MyComponent(env);
    await component.mount(fixture);
    expect(fixture.innerHTML).toBe("<div>hey1</div>");
    component.state.value++;
@@ -479,13 +280,13 @@ describe("hooks", () => {
                <input t-ref="input2"/>
            </div>`;

-        constructor() {
-          super();
+        constructor(env) {
+          super(env);
          useAutofocus("input2");
        }
      }

-      const component = new SomeComponent();
+      const component = new SomeComponent(env);
      await component.mount(fixture);
      expect(fixture.innerHTML).toBe("<div><input><input></div>");
      const input2 = fixture.querySelectorAll("input")[1];
@@ -501,13 +302,13 @@ describe("hooks", () => {
            </div>`;

        state = useState({ flag: false });
-        constructor() {
-          super();
+        constructor(env) {
+          super(env);
          useAutofocus("input2");
        }
      }

-      const component = new SomeComponent();
+      const component = new SomeComponent(env);
      await component.mount(fixture);
      expect(fixture.innerHTML).toBe("<div><input></div>");
      expect(document.activeElement).toBe(document.body);
@@ -522,12 +323,12 @@ describe("hooks", () => {
  test("can use sub env", async () => {
    class TestComponent extends Component<any, any> {
      static template = xml`<div><t t-esc="env.val"/></div>`;
-      constructor() {
-        super();
+      constructor(env) {
+        super(env);
        useSubEnv({ val: 3 });
      }
    }
-    const component = new TestComponent();
+    const component = new TestComponent(env);
    await component.mount(fixture);
    expect(fixture.innerHTML).toBe("<div>3</div>");
    expect(env).not.toHaveProperty("val");
@@ -537,59 +338,22 @@ describe("hooks", () => {
  test("parent and child env", async () => {
    class Child extends Component<any, any> {
      static template = xml`<div><t t-esc="env.val"/></div>`;
-      constructor(parent, props) {
-        super(parent, props);
+      constructor(env) {
+        super(env);
        useSubEnv({ val: 5 });
      }
    }

    class Parent extends Component<any, any> {
      static template = xml`<div><t t-esc="env.val"/><Child/></div>`;
-      static components = { Child };
-      constructor() {
-        super();
+      static components = { Child}
+      constructor(env) {
+        super(env);
        useSubEnv({ val: 3 });
      }
    }
-    const component = new Parent();
+    const component = new Parent(env);
    await component.mount(fixture);
-    expect(fixture.innerHTML).toBe("<div>3<div>5</div></div>");
-  });
-
-  test("can use onWillStart, onWillUpdateProps", async () => {
-    const steps: string[] = [];
-    function useMyHook() {
-      onWillStart(() => {
-        steps.push("onWillStart");
-      });
-      onWillUpdateProps(nextProps => {
-        expect(nextProps).toEqual({ value: 2 });
-        steps.push("onWillUpdateProps");
-      });
-    }
-    class MyComponent extends Component<any, any> {
-      static template = xml`<span><t t-esc="props.value"/></span>`;
-      constructor(parent, props) {
-        super(parent, props);
-        useMyHook();
-      }
-    }
-    class App extends Component<any, any> {
-      static template = xml`<div><MyComponent value="state.value"/></div>`;
-      static components = { MyComponent };
-      state = useState({ value: 1 });
-    }
-
-    const app = new App();
-    await app.mount(fixture);
-    expect(app).not.toHaveProperty("willStart");
-    expect(app).not.toHaveProperty("willUpdateProps");
-    expect(fixture.innerHTML).toBe("<div><span>1</span></div>");
-    expect(steps).toEqual(["onWillStart"]);
-
-    app.state.value = 2;
-    await nextTick();
-    expect(fixture.innerHTML).toBe("<div><span>2</span></div>");
-    expect(steps).toEqual(["onWillStart", "onWillUpdateProps"]);
+    expect(fixture.innerHTML).toBe( "<div>3<div>5</div></div>");
  });
 });
@@ -1,188 +0,0 @@
-import { AsyncRoot } from "../../src/misc/async_root";
-import { useState } from "../../src/hooks";
-import { xml } from "../../src/tags";
-import { makeDeferred, makeTestFixture, makeTestEnv, nextTick } from "../helpers";
-import { Component } from "../../src/component/component";
-
-//------------------------------------------------------------------------------
-// Setup and helpers
-//------------------------------------------------------------------------------
-
-// We create before each test:
-// - fixture: a div, appended to the DOM, intended to be the target of dom
-//   manipulations.  Note that it is removed after each test.
-// - a test env, necessary to create components, that is set as env
-
-let fixture: HTMLElement;
-
-beforeEach(() => {
-  fixture = makeTestFixture();
-  Component.env = makeTestEnv();
-});
-
-afterEach(() => {
-  fixture.remove();
-});
-
-describe("Asyncroot", () => {
-  test("delayed component with AsyncRoot component", async () => {
-    let def;
-    class Child extends Component<any, any> {
-      static template = xml`<span><t t-esc="props.val"/></span>`;
-    }
-    class AsyncChild extends Child {
-      willUpdateProps() {
-        return def;
-      }
-    }
-    class Parent extends Component<any, any> {
-      static template = xml`
-          <div>
-            <button t-on-click="updateApp">Update App State</button>
-            <div class="children">
-              <Child val="state.val"/>
-              <AsyncRoot>
-                  <AsyncChild val="state.val"/>
-              </AsyncRoot>
-            </div>
-          </div>`;
-      static components = { Child, AsyncChild, AsyncRoot };
-      state = useState({ val: 0 });
-
-      updateApp() {
-        this.state.val++;
-      }
-    }
-
-    const parent = new Parent();
-    await parent.mount(fixture);
-
-    expect(fixture.querySelector(".children")!.innerHTML).toBe("<span>0</span><span>0</span>");
-
-    // click on button to increment Parent counter
-    def = makeDeferred();
-    fixture.querySelector("button")!.click();
-    await nextTick();
-
-    expect(fixture.querySelector(".children")!.innerHTML).toBe("<span>1</span><span>0</span>");
-
-    def.resolve();
-    await nextTick();
-
-    expect(fixture.querySelector(".children")!.innerHTML).toBe("<span>1</span><span>1</span>");
-  });
-
-  test("fast component with AsyncRoot", async () => {
-    let def;
-    class Child extends Component<any, any> {
-      static template = xml`<span><t t-esc="props.val"/></span>`;
-    }
-    class AsyncChild extends Child {
-      willUpdateProps() {
-        return def;
-      }
-    }
-
-    class Parent extends Component<any, any> {
-      static template = xml`
-          <div>
-            <button t-on-click="updateApp">Update App State</button>
-            <div class="children">
-              <AsyncRoot>
-                <Child val="state.val"/>
-              </AsyncRoot>
-              <AsyncChild val="state.val"/>
-            </div>
-          </div>`;
-      static components = { Child, AsyncChild, AsyncRoot };
-      state = useState({ val: 0 });
-
-      updateApp() {
-        this.state.val++;
-      }
-    }
-
-    const parent = new Parent();
-    await parent.mount(fixture);
-
-    expect(fixture.querySelector(".children")!.innerHTML).toBe("<span>0</span><span>0</span>");
-
-    // click on button to increment Parent counter
-    def = makeDeferred();
-    fixture.querySelector("button")!.click();
-    await nextTick();
-
-    expect(fixture.querySelector(".children")!.innerHTML).toBe("<span>1</span><span>0</span>");
-
-    def.resolve();
-    await nextTick();
-
-    expect(fixture.querySelector(".children")!.innerHTML).toBe("<span>1</span><span>1</span>");
-  });
-
-  test("asyncroot component: mixed re-renderings", async () => {
-    let def;
-    class Child extends Component<any, any> {
-      static template = xml`
-        <span t-on-click="increment">
-          <t t-esc="state.val"/>/<t t-esc="props.val"/>
-        </span>`;
-      state = useState({ val: 0 });
-
-      increment() {
-        this.state.val++;
-      }
-    }
-    class AsyncChild extends Child {
-      willUpdateProps() {
-        return def;
-      }
-    }
-    class Parent extends Component<any, any> {
-      static template = xml`
-        <div>
-          <button t-on-click="updateApp">Update App State</button>
-          <div class="children">
-            <Child val="state.val"/>
-            <AsyncRoot>
-              <AsyncChild val="state.val"/>
-            </AsyncRoot>
-          </div>
-        </div>`;
-      static components = { Child, AsyncChild, AsyncRoot };
-      state = useState({ val: 0 });
-
-      updateApp() {
-        this.state.val++;
-      }
-    }
-
-    const parent = new Parent();
-    await parent.mount(fixture);
-
-    expect(fixture.querySelector(".children")!.innerHTML).toBe("<span>0/0</span><span>0/0</span>");
-
-    // click on button to increment Parent counter
-    def = makeDeferred();
-    fixture.querySelector("button")!.click();
-    await nextTick();
-
-    expect(fixture.querySelector(".children")!.innerHTML).toBe("<span>0/1</span><span>0/0</span>");
-
-    // click on each Child to increment their local counter
-    const children = parent.el!.querySelectorAll("span");
-    children[0]!.click();
-    await nextTick();
-    expect(fixture.querySelector(".children")!.innerHTML).toBe("<span>1/1</span><span>0/0</span>");
-
-    children[1]!.click();
-    await nextTick();
-    expect(fixture.querySelector(".children")!.innerHTML).toBe("<span>1/1</span><span>0/0</span>");
-
-    // finalize first re-rendering (coming from the props update)
-    def.resolve();
-    await nextTick();
-
-    expect(fixture.querySelector(".children")!.innerHTML).toBe("<span>1/1</span><span>1/1</span>");
-  });
-});
@@ -1,890 +0,0 @@
-import { Portal } from "../../src/misc/portal";
-import { xml } from "../../src/tags";
-import { makeTestFixture, makeTestEnv, nextTick } from "../helpers";
-import { Component } from "../../src/component/component";
-import { useState } from "../../src/hooks";
-import { QWeb } from "../../src/qweb";
-
-//------------------------------------------------------------------------------
-// Setup and helpers
-//------------------------------------------------------------------------------
-
-// We create before each test:
-// - fixture: a div, appended to the DOM, intended to be the target of dom
-//   manipulations.  Note that it is removed after each test.
-// - outside: a div with id #outside appended into fixture, meant to be used as
-//   target by Portal component
-// - a test env, necessary to create components, that is set on Component
-
-let fixture: HTMLElement;
-let outside: HTMLElement;
-
-beforeEach(() => {
-  fixture = makeTestFixture();
-  outside = document.createElement("div");
-  outside.setAttribute("id", "outside");
-  fixture.appendChild(outside);
-
-  Component.env = makeTestEnv();
-});
-
-afterEach(() => {
-  fixture.remove();
-});
-
-describe("Portal: Props validation", () => {
-  test("target is mandatory", async () => {
-    const dev = QWeb.dev;
-    QWeb.dev = true;
-    class Parent extends Component<any, any> {
-      static components = { Portal };
-      static template = xml`
-        <div>
-          <Portal>
-            <div>2</div>
-          </Portal>
-        </div>`;
-    }
-    let error;
-    try {
-      const parent = new Parent();
-      await parent.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeDefined();
-    expect(error.message).toBe(`Missing props 'target' (component 'Portal')`);
-
-    QWeb.dev = dev;
-  });
-
-  test("target is not list", async () => {
-    const dev = QWeb.dev;
-    QWeb.dev = true;
-    class Parent extends Component<any, any> {
-      static components = { Portal };
-      static template = xml`
-        <div>
-          <Portal target="['body']">
-            <div>2</div>
-          </Portal>
-        </div>`;
-    }
-    let error;
-    try {
-      const parent = new Parent();
-      await parent.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeDefined();
-    expect(error.message).toBe(`Invalid Prop 'target' in component 'Portal'`);
-
-    QWeb.dev = dev;
-  });
-});
-
-describe("Portal: Basic use and DOM placement", () => {
-  test("basic use of portal", async () => {
-    const dev = QWeb.dev;
-    QWeb.dev = true;
-    class Parent extends Component<any, any> {
-      static components = { Portal };
-      static template = xml`
-        <div>
-          <span>1</span>
-          <Portal target="'#outside'">
-            <div>2</div>
-          </Portal>
-        </div>`;
-    }
-    let error;
-    let parent;
-    try {
-      parent = new Parent();
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeUndefined();
-    await parent.mount(fixture);
-    expect(outside.innerHTML).toBe("<div>2</div>");
-    expect(parent.el!.outerHTML).toBe("<div><span>1</span><portal></portal></div>");
-    QWeb.dev = dev;
-  });
-
-  test("conditional use of Portal", async () => {
-    class Parent extends Component<any, any> {
-      static components = { Portal };
-      static template = xml`
-        <div>
-          <span>1</span>
-          <Portal target="'#outside'" t-if="state.hasPortal">
-            <div>2</div>
-          </Portal>
-        </div>`;
-
-      state = useState({ hasPortal: false });
-    }
-
-    const parent = new Parent();
-    await parent.mount(fixture);
-    expect(outside.innerHTML).toBe("");
-    expect(parent.el!.outerHTML).toBe("<div><span>1</span></div>");
-
-    parent.state.hasPortal = true;
-    await nextTick();
-    expect(outside.innerHTML).toBe("<div>2</div>");
-    expect(parent.el!.outerHTML).toBe("<div><span>1</span><portal></portal></div>");
-
-    parent.state.hasPortal = false;
-    await nextTick();
-    expect(outside.innerHTML).toBe("");
-    expect(parent.el!.outerHTML).toBe("<div><span>1</span></div>");
-
-    parent.state.hasPortal = true;
-    await nextTick();
-    expect(outside.innerHTML).toBe("<div>2</div>");
-    expect(parent.el!.outerHTML).toBe("<div><span>1</span><portal></portal></div>");
-  });
-
-  test("conditional use of Portal (with sub Component)", async () => {
-    class Child extends Component<any, any> {
-      static template = xml`<div><t t-esc="props.val"/></div>`;
-    }
-    class Parent extends Component<any, any> {
-      static components = { Portal, Child };
-      static template = xml`
-        <div>
-          <span>1</span>
-          <Portal t-if="state.hasPortal" target="'#outside'">
-            <Child val="state.val"/>
-          </Portal>
-        </div>`;
-      state = useState({ hasPortal: false, val: 1 });
-    }
-
-    const parent = new Parent();
-    await parent.mount(fixture);
-    expect(outside.innerHTML).toBe("");
-    expect(parent.el!.outerHTML).toBe("<div><span>1</span></div>");
-
-    parent.state.hasPortal = true;
-    await nextTick();
-    expect(outside.innerHTML).toBe("<div>1</div>");
-    expect(parent.el!.outerHTML).toBe("<div><span>1</span><portal></portal></div>");
-
-    parent.state.hasPortal = false;
-    await nextTick();
-    expect(outside.innerHTML).toBe("");
-    expect(parent.el!.outerHTML).toBe("<div><span>1</span></div>");
-
-    parent.state.val = 2;
-    await nextTick();
-    expect(outside.innerHTML).toBe("");
-    expect(parent.el!.outerHTML).toBe("<div><span>1</span></div>");
-
-    parent.state.hasPortal = true;
-    await nextTick();
-    expect(outside.innerHTML).toBe("<div>2</div>");
-    expect(parent.el!.outerHTML).toBe("<div><span>1</span><portal></portal></div>");
-  });
-
-  test("with target in template (before portal)", async () => {
-    class Parent extends Component<any, any> {
-      static components = { Portal };
-      static template = xml`
-        <div>
-          <div id="local-target"></div>
-          <span>1</span>
-          <Portal target="'#local-target'">
-            <p>2</p>
-          </Portal>
-        </div>`;
-    }
-
-    const parent = new Parent();
-    await parent.mount(fixture);
-    expect(parent.el!.innerHTML).toBe(
-      '<div id="local-target"><p>2</p></div><span>1</span><portal></portal>'
-    );
-  });
-
-  test("with target in template (after portal)", async () => {
-    class Parent extends Component<any, any> {
-      static components = { Portal };
-      static template = xml`
-        <div>
-          <span>1</span>
-          <Portal target="'#local-target'">
-            <p>2</p>
-          </Portal>
-          <div id="local-target"></div>
-        </div>`;
-    }
-
-    const parent = new Parent();
-    await parent.mount(fixture);
-    expect(parent.el!.innerHTML).toBe(
-      '<span>1</span><portal></portal><div id="local-target"><p>2</p></div>'
-    );
-  });
-
-  test("portal with target not in dom", async () => {
-    const consoleError = console.error;
-    console.error = jest.fn(() => {});
-
-    class Parent extends Component<any, any> {
-      static components = { Portal };
-      static template = xml`
-        <div>
-          <Portal target="'#does-not-exist'">
-            <div>2</div>
-          </Portal>
-        </div>`;
-    }
-
-    const parent = new Parent();
-    let error;
-    try {
-      await parent.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
-
-    expect(error).toBeDefined();
-    expect(error.message).toBe('Could not find any match for "#does-not-exist"');
-    expect(console.error).toBeCalledTimes(0);
-    expect(fixture.innerHTML).toBe(`<div id="outside"></div>`);
-    console.error = consoleError;
-  });
-
-  test("portal with child and props", async () => {
-    const steps: string[] = [];
-    class Child extends Component<any, any> {
-      static template = xml`<span><t t-esc="props.val"/></span>`;
-      mounted() {
-        steps.push("mounted");
-        expect(outside.innerHTML).toBe("<span>1</span>");
-      }
-      patched() {
-        steps.push("patched");
-        expect(outside.innerHTML).toBe("<span>2</span>");
-      }
-    }
-    class Parent extends Component<any, any> {
-      static components = { Portal, Child };
-      static template = xml`
-        <div>
-          <Portal target="'#outside'">
-            <Child val="state.val"/>
-          </Portal>
-        </div>`;
-      state = useState({ val: 1 });
-    }
-
-    const parent = new Parent();
-    await parent.mount(fixture);
-    expect(outside.innerHTML).toBe("<span>1</span>");
-    expect(parent.el!.innerHTML).toBe("<portal></portal>");
-
-    parent.state.val = 2;
-    await nextTick();
-    expect(outside.innerHTML).toBe("<span>2</span>");
-    expect(parent.el!.innerHTML).toBe("<portal></portal>");
-    expect(steps).toEqual(["mounted", "patched"]);
-  });
-
-  test("portal with only text as content", async () => {
-    const consoleError = console.error;
-    console.error = jest.fn(() => {});
-
-    class Parent extends Component<any, any> {
-      static components = { Portal };
-      static template = xml`
-        <div>
-          <Portal target="'#outside'">
-            <t t-esc="'only text'"/>
-          </Portal>
-        </div>`;
-    }
-
-    const parent = new Parent();
-    let error;
-    try {
-      await parent.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeDefined();
-    expect(error.message).toBe("Portal must have exactly one non-text child (has 0)");
-    expect(console.error).toBeCalledTimes(0);
-    expect(fixture.innerHTML).toBe(`<div id="outside"></div>`);
-    console.error = consoleError;
-  });
-
-  test("portal with no content", async () => {
-    const consoleError = console.error;
-    console.error = jest.fn(() => {});
-
-    class Parent extends Component<any, any> {
-      static components = { Portal };
-      static template = xml`
-        <div>
-          <Portal target="'#outside'">
-            <t t-if="false" t-esc="'ABC'"/>
-          </Portal>
-        </div>`;
-    }
-
-    const parent = new Parent();
-    let error;
-    try {
-      await parent.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeDefined();
-    expect(error.message).toBe("Portal must have exactly one non-text child (has 0)");
-    expect(console.error).toBeCalledTimes(0);
-    expect(fixture.innerHTML).toBe(`<div id="outside"></div>`);
-    console.error = consoleError;
-  });
-
-  test("portal with many children", async () => {
-    const consoleError = console.error;
-    console.error = jest.fn(() => {});
-
-    class Parent extends Component<any, any> {
-      static components = { Portal };
-      static template = xml`
-        <div>
-          <Portal target="'#outside'">
-            <div>1</div>
-            <p>2</p>
-          </Portal>
-        </div>`;
-    }
-    const parent = new Parent();
-    let error;
-    try {
-      await parent.mount(fixture);
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeDefined();
-    expect(error.message).toBe("Portal must have exactly one non-text child (has 2)");
-    expect(console.error).toBeCalledTimes(0);
-    expect(fixture.innerHTML).toBe(`<div id="outside"></div>`);
-    console.error = consoleError;
-  });
-
-  test("portal with dynamic body", async () => {
-    class Parent extends Component<any, any> {
-      static components = { Portal };
-      static template = xml`
-        <div>
-          <Portal target="'#outside'">
-            <span t-if="state.val" t-esc="state.val"/>
-            <div t-else=""/>
-          </Portal>
-        </div>`;
-      state = useState({ val: "ab" });
-    }
-
-    const parent = new Parent();
-    await parent.mount(fixture);
-
-    expect(outside.innerHTML).toBe(`<span>ab</span>`);
-
-    parent.state.val = "";
-    await nextTick();
-    expect(outside.innerHTML).toBe(`<div></div>`);
-  });
-
-  test("portal could have dynamically no content", async () => {
-    const consoleError = console.error;
-    console.error = jest.fn(() => {});
-
-    class Parent extends Component<any, any> {
-      static components = { Portal };
-      static template = xml`
-        <div>
-          <Portal target="'#outside'">
-            <span t-if="state.val" t-esc="state.val"/>
-          </Portal>
-        </div>`;
-      state = { val: "ab" };
-    }
-    const parent = new Parent();
-    await parent.mount(fixture);
-
-    expect(outside.innerHTML).toBe(`<span>ab</span>`);
-
-    let error;
-    try {
-      parent.state.val = "";
-      await parent.render();
-    } catch (e) {
-      error = e;
-    }
-    expect(outside.innerHTML).toBe(``);
-
-    expect(error).toBeDefined();
-    expect(error.message).toBe("Portal must have exactly one non-text child (has 0)");
-
-    expect(console.error).toBeCalledTimes(0);
-    console.error = consoleError;
-  });
-
-  test("lifecycle hooks of portal sub component are properly called", async () => {
-    const steps: any[] = [];
-
-    class Child extends Component<any, any> {
-      static template = xml`<span t-esc="props.val"/>`;
-      mounted() {
-        steps.push("child:mounted");
-      }
-      willPatch() {
-        steps.push("child:willPatch");
-      }
-      patched() {
-        steps.push("child:patched");
-      }
-      willUnmount() {
-        steps.push("child:willUnmount");
-      }
-    }
-    class Parent extends Component<any, any> {
-      static components = { Portal, Child };
-      static template = xml`
-        <div>
-          <Portal t-if="state.hasChild" target="'#outside'">
-            <Child val="state.val"/>
-          </Portal>
-        </div>`;
-      state = useState({ hasChild: false, val: 1 });
-      mounted() {
-        steps.push("parent:mounted");
-      }
-      willPatch() {
-        steps.push("parent:willPatch");
-      }
-      patched() {
-        steps.push("parent:patched");
-      }
-      willUnmount() {
-        steps.push("parent:willUnmount");
-      }
-    }
-    const parent = new Parent();
-    await parent.mount(fixture);
-    expect(steps).toEqual(["parent:mounted"]);
-
-    parent.state.hasChild = true;
-    await nextTick();
-    expect(steps).toEqual([
-      "parent:mounted",
-      "parent:willPatch",
-      "child:mounted",
-      "parent:patched"
-    ]);
-
-    parent.state.val = 2;
-    await nextTick();
-    expect(steps).toEqual([
-      "parent:mounted",
-      "parent:willPatch",
-      "child:mounted",
-      "parent:patched",
-      "parent:willPatch",
-      "child:willPatch",
-      "child:patched",
-      "parent:patched"
-    ]);
-
-    parent.state.hasChild = false;
-    await nextTick();
-    expect(steps).toEqual([
-      "parent:mounted",
-      "parent:willPatch",
-      "child:mounted",
-      "parent:patched",
-      "parent:willPatch",
-      "child:willPatch",
-      "child:patched",
-      "parent:patched",
-      "parent:willPatch",
-      "child:willUnmount",
-      "parent:patched"
-    ]);
-  });
-
-  test("portal destroys on crash", async () => {
-    class Child extends Component<any, any> {
-      static template = xml`<span t-esc="props.error and this.will.crash" />`;
-      state = {};
-    }
-    class Parent extends Component<any, any> {
-      static components = { Portal, Child };
-      static template = xml`
-        <div>
-          <Portal target="'#outside'" >
-            <Child error="state.error"/>
-          </Portal>
-        </div>`;
-      state = { error: false };
-    }
-
-    const parent = new Parent();
-    await parent.mount(fixture);
-    parent.state.error = true;
-
-    let error;
-    try {
-      await parent.render();
-    } catch (e) {
-      error = e;
-    }
-    expect(error).toBeDefined();
-    expect(error.message).toBe("Cannot read property 'crash' of undefined");
-  });
-
-  test("portal manual unmount", async () => {
-    class Parent extends Component<any, any> {
-      static components = { Portal };
-      static template = xml`
-        <div>
-          <Portal target="'#outside'">
-            <span>gloria</span>
-          </Portal>
-        </div>`;
-    }
-
-    const parent = new Parent();
-    await parent.mount(fixture);
-
-    expect(outside.innerHTML).toBe("<span>gloria</span>");
-    expect(parent.el!.innerHTML).toBe("<portal></portal>");
-
-    parent.unmount();
-    expect(outside.innerHTML).toBe("");
-    expect(parent.el!.innerHTML).toBe("<portal><span>gloria</span></portal>");
-
-    await parent.mount(fixture);
-    expect(outside.innerHTML).toBe("<span>gloria</span>");
-    expect(parent.el!.innerHTML).toBe("<portal></portal>");
-  });
-
-  test("portal manual unmount with subcomponent", async () => {
-    expect.assertions(9);
-    class Child extends Component<any, any> {
-      static template = xml`<span>gloria</span>`;
-      mounted() {
-        expect(outside.contains(this.el)).toBeTruthy();
-      }
-      willUnmount() {
-        expect(outside.contains(this.el)).toBeTruthy();
-      }
-    }
-    class Parent extends Component<any, any> {
-      static components = { Portal, Child };
-      static template = xml`
-        <div>
-          <Portal target="'#outside'">
-            <Child />
-          </Portal>
-        </div>`;
-    }
-
-    const parent = new Parent();
-    await parent.mount(fixture);
-
-    expect(outside.innerHTML).toBe("<span>gloria</span>");
-    expect(parent.el!.innerHTML).toBe("<portal></portal>");
-
-    parent.unmount();
-    expect(outside.innerHTML).toBe("");
-    expect(parent.el!.innerHTML).toBe("<portal><span>gloria</span></portal>");
-
-    await parent.mount(fixture);
-    expect(outside.innerHTML).toBe("<span>gloria</span>");
-    expect(parent.el!.innerHTML).toBe("<portal></portal>");
-  });
-});
-
-describe("Portal: Events handling", () => {
-  test("events triggered on movable pure node are handled", async () => {
-    class Parent extends Component<any, any> {
-      static components = { Portal };
-      static template = xml`
-        <div>
-          <Portal target="'#outside'">
-            <span id="trigger-me" t-on-custom="_onCustom" t-esc="state.val"/>
-          </Portal>
-        </div>`;
-      state = useState({ val: "ab" });
-
-      _onCustom() {
-        this.state.val = "triggered";
-      }
-    }
-    const parent = new Parent();
-    await parent.mount(fixture);
-
-    expect(outside.innerHTML).toBe(`<span id="trigger-me">ab</span>`);
-    outside.querySelector("#trigger-me")!.dispatchEvent(new Event("custom"));
-    await nextTick();
-    expect(outside.innerHTML).toBe(`<span id="trigger-me">triggered</span>`);
-  });
-
-  test("events triggered on movable owl components are redirected", async () => {
-    let childInst: Component<any, any> | null = null;
-    class Child extends Component<any, any> {
-      static template = xml`
-         <span t-on-custom="_onCustom" t-esc="props.val"/>`;
-
-      constructor(parent, props) {
-        super(parent, props);
-        childInst = this;
-      }
-
-      _onCustom() {
-        this.trigger("custom-portal");
-      }
-    }
-    class Parent extends Component<any, any> {
-      static components = { Portal, Child };
-      static template = xml`
-        <div t-on-custom-portal="_onCustomPortal">
-          <Portal target="'#outside'">
-            <Child val="state.val"/>
-          </Portal>
-        </div>`;
-      state = useState({ val: "ab" });
-
-      _onCustomPortal() {
-        this.state.val = "triggered";
-      }
-    }
-    const parent = new Parent();
-    await parent.mount(fixture);
-
-    expect(outside.innerHTML).toBe(`<span>ab</span>`);
-    childInst!.trigger("custom");
-    await nextTick();
-    expect(outside.innerHTML).toBe(`<span>triggered</span>`);
-  });
-
-  test("events triggered on contained movable owl components are redirected", async () => {
-    const steps: string[] = [];
-    let childInst: Component<any, any> | null = null;
-    class Child extends Component<any, any> {
-      static template = xml`
-         <span t-on-custom="_onCustom"/>`;
-
-      constructor(parent, props) {
-        super(parent, props);
-        childInst = this;
-      }
-
-      _onCustom() {
-        this.trigger("custom-portal");
-      }
-    }
-    class Parent extends Component<any, any> {
-      static components = { Portal, Child };
-      static template = xml`
-        <div t-on-custom="_handled" t-on-custom-portal="_handled">
-          <Portal target="'#outside'">
-            <div>
-              <Child/>
-            </div>
-          </Portal>
-        </div>`;
-
-      _handled(ev) {
-        steps.push(ev.type);
-      }
-    }
-    const parent = new Parent();
-    await parent.mount(fixture);
-
-    childInst!.trigger("custom");
-    await nextTick();
-
-    // This is expected because trigger is synchronous
-    expect(steps).toMatchObject(["custom-portal", "custom"]);
-  });
-
-  test("Dom events are not mapped", async () => {
-    let childInst: Component<any, any> | null = null;
-    const steps: string[] = [];
-    class Child extends Component<any, any> {
-      static template = xml`
-        <button>child</button>`;
-
-      constructor(parent, props) {
-        super(parent, props);
-        childInst = this;
-      }
-    }
-    class Parent extends Component<any, any> {
-      static components = { Portal, Child };
-      static template = xml`
-        <div t-on-click="_handled">
-          <Portal target="'#outside'">
-            <Child />
-          </Portal>
-        </div>`;
-
-      _handled(ev) {
-        steps.push(ev.type as string);
-      }
-    }
-    const bodyListener = ev => {
-      steps.push(`body: ${ev.type}`);
-    };
-    document.body.addEventListener("click", bodyListener);
-
-    const parent = new Parent();
-    await parent.mount(fixture);
-    childInst!.el!.click();
-
-    expect(steps).toEqual(["body: click"]);
-    document.body.removeEventListener("click", bodyListener);
-  });
-
-  test("Nested portals event propagation", async () => {
-    const outside2 = document.createElement("div");
-    outside2.setAttribute("id", "outside2");
-    fixture.appendChild(outside2);
-
-    const steps: Array<string> = [];
-    let childInst: Component<any, any> | null = null;
-    class Child2 extends Component<any, any> {
-      static template = xml`<div>child2</div>`;
-      constructor(parent, props) {
-        super(parent, props);
-        childInst = this;
-      }
-    }
-    class Child extends Component<any, any> {
-      static components = { Portal, Child2 };
-      static template = xml`
-        <Portal target="'#outside2'">
-          <Child2 />
-        </Portal>`;
-    }
-    class Parent extends Component<any, any> {
-      static components = { Portal, Child };
-      static template = xml`
-        <div t-on-custom='_handled'>
-          <Portal target="'#outside'">
-            <Child/>
-          </Portal>
-        </div>`;
-
-      _handled(ev) {
-        steps.push(`${ev.type} from ${ev.originalComponent.constructor.name}`);
-      }
-    }
-
-    const parent = new Parent();
-    await parent.mount(fixture);
-
-    childInst!.trigger("custom");
-    expect(steps).toEqual(["custom from Child2"]);
-  });
-
-  test("portal's parent's env is not polluted", async () => {
-    class Child extends Component<any, any> {
-      static template = xml`
-        <button>child</button>`;
-    }
-    class Parent extends Component<any, any> {
-      static components = { Portal, Child };
-      static template = xml`
-        <div>
-          <Portal target="'#outside'">
-            <Child />
-          </Portal>
-        </div>`;
-    }
-    const parent = new Parent();
-    const parentEnv = Object.assign({}, parent.env);
-    await parent.mount(fixture);
-    expect(parentEnv).toStrictEqual(parent.env);
-  });
-
-  test("Portal composed with t-slot", async () => {
-    const steps: Array<string> = [];
-    let childInst: Component<any, any> | null = null;
-    class Child2 extends Component<any, any> {
-      static template = xml`<div>child2</div>`;
-      constructor(parent, props) {
-        super(parent, props);
-        childInst = this;
-      }
-    }
-    class Child extends Component<any, any> {
-      static components = { Portal, Child2 };
-      static template = xml`
-        <Portal target="'#outside'">
-          <t t-slot="default"/>
-        </Portal>`;
-    }
-    class Parent extends Component<any, any> {
-      static components = { Child, Child2 };
-      static template = xml`
-        <div t-on-custom='_handled'>
-          <Child>
-            <Child2/>
-          </Child>
-        </div>`;
-
-      _handled(ev) {
-        steps.push(ev.type as string);
-      }
-    }
-
-    const parent = new Parent();
-    await parent.mount(fixture);
-
-    childInst!.trigger("custom");
-    expect(steps).toEqual(["custom"]);
-  });
-});
-
-describe("Portal: UI/UX", () => {
-  test("focus is kept across re-renders", async () => {
-    class Child extends Component<any, any> {
-      static template = xml`
-        <input id="target-me" t-att-placeholder="props.val"/>`;
-    }
-    class Parent extends Component<any, any> {
-      static components = { Portal, Child };
-      static template = xml`
-        <div>
-          <Portal target="'#outside'">
-            <Child val="state.val"/>
-          </Portal>
-        </div>`;
-      state = useState({ val: "ab" });
-    }
-    const parent = new Parent();
-    await parent.mount(fixture);
-    const input = document.querySelector("#target-me");
-    expect(input!.nodeName).toBe("INPUT");
-    expect((input as HTMLInputElement).placeholder).toBe("ab");
-
-    (input as HTMLInputElement).focus();
-    expect(document.activeElement === input).toBeTruthy();
-
-    parent.state.val = "bc";
-    await nextTick();
-    const inputReRendered = document.querySelector("#target-me");
-    expect(inputReRendered!.nodeName).toBe("INPUT");
-    expect((inputReRendered as HTMLInputElement).placeholder).toBe("bc");
-    expect(document.activeElement === inputReRendered).toBeTruthy();
-  });
-});
@@ -1,6 +1,5 @@
 import { QWeb } from "../../src/qweb/index";
-import { nextTick, normalize, renderToDOM, renderToString, trim } from "../helpers";
-import { patch } from "../../src/vdom";
+import { normalize, renderToDOM, renderToString, trim, nextTick } from "../helpers";

 //------------------------------------------------------------------------------
 // Setup and helpers
@@ -46,24 +45,14 @@ describe("static templates", () => {
    expect(renderToString(qweb, "test")).toBe("<div>word</div>");
  });

-  test("div with a class attribute", () => {
-    qweb.addTemplate("test", `<div class="abc">word</div>`);
-    expect(renderToString(qweb, "test")).toBe(`<div class="abc">word</div>`);
-  });
-
-  test("div with a empty class attribute", () => {
-    qweb.addTemplate("test", `<div class="">word</div>`);
-    expect(renderToString(qweb, "test")).toBe(`<div>word</div>`);
-  });
-
  test("div with a span child node", () => {
    qweb.addTemplate("test", "<div><span>word</span></div>");
    expect(renderToString(qweb, "test")).toBe("<div><span>word</span></div>");
  });

-  test("properly handle comments", () => {
+  test("ignore comments", () => {
    qweb.addTemplate("test", "<div>hello <!-- comment-->owl</div>");
-    expect(renderToString(qweb, "test")).toBe("<div>hello <!-- comment-->owl</div>");
+    expect(renderToString(qweb, "test")).toBe("<div>hello owl</div>");
  });
 });

@@ -90,12 +79,19 @@ describe("error handling", () => {
    expect(() => qweb.addTemplate("test", "<div/>")).toThrow("already defined");
  });

-  test("addTemplates throw if parser error", () => {
+  test("loadTemplates throw if parser error", () => {
    expect(() => {
      qweb.addTemplates("<templates><abc>></templates>");
    }).toThrow("Invalid XML in template");
  });

+  test("nice error when t-on-directive is evaluated with a missing handler", () => {
+    qweb.addTemplate("templatename", `<div t-on-click="somemethod"></div>`);
+    expect(() => qweb.render("templatename", {}, { handlers: [] })).toThrow(
+      "Missing handler 'somemethod' when evaluating template 'templatename'"
+    );
+  });
+
  test("nice error when t-on is evaluated with a missing event", () => {
    qweb.addTemplate("templatename", `<div t-on="somemethod"></div>`);
    expect(() => qweb.render("templatename", { someMethod() {} }, { handlers: [] })).toThrow(
@@ -139,17 +135,6 @@ describe("t-esc", () => {
    qweb.addTemplate("test", `<span t-esc="var">nope</span>`);
    expect(renderToString(qweb, "test")).toBe("<span>nope</span>");
  });
-  test("t-esc is escaped", () => {
-    qweb.addTemplate("test", `<div><t t-set="var"><p>escaped</p></t><t t-esc="var"/></div>`);
-    const domRendered = renderToDOM(qweb, "test");
-    expect(domRendered.textContent).toBe("<p>escaped</p>");
-  });
-  test("t-esc=0 is escaped", () => {
-    qweb.addTemplate("test", `<span><t t-esc="0"/></span>`);
-    qweb.addTemplate("testCaller", `<div><t t-call="test"><p>escaped</p></t></div>`);
-    const domRendered = renderToDOM(qweb, "testCaller") as HTMLElement;
-    expect(domRendered.querySelector("span")!.textContent).toBe("<p>escaped</p>");
-  });
 });

 describe("t-raw", () => {
@@ -263,82 +248,6 @@ describe("t-set", () => {
    );
    expect(renderToString(qweb, "test", { somevariable: 43 })).toBe("<div>45</div>");
  });
-
-  test("t-set, t-if, and mix of expression/body lookup, 1", () => {
-    qweb.addTemplate(
-      "test",
-      `<div>
-        <t t-if="flag" t-set="ourvar">1</t>
-        <t t-else="" t-set="ourvar" t-value="0"></t>
-        <t t-esc="ourvar"/>
-      </div>`
-    );
-    expect(renderToString(qweb, "test", { flag: true })).toBe("<div>1</div>");
-    expect(renderToString(qweb, "test", { flag: false })).toBe("<div>0</div>");
-  });
-
-  test("t-set, t-if, and mix of expression/body lookup, 2", () => {
-    qweb.addTemplate(
-      "test",
-      `<div>
-        <t t-if="flag" t-set="ourvar" t-value="1"></t>
-        <t t-else="" t-set="ourvar">0</t>
-        <t t-esc="ourvar"/>
-      </div>`
-    );
-    expect(renderToString(qweb, "test", { flag: true })).toBe("<div>1</div>");
-    expect(renderToString(qweb, "test", { flag: false })).toBe("<div>0</div>");
-  });
-
-  test("t-set body is evaluated immediately", () => {
-    qweb.addTemplate(
-      "test",
-      `<div>
-        <t t-set="v1" t-value="'before'"/>
-        <t t-set="v2">
-          <span><t t-esc="v1"/></span>
-        </t>
-        <t t-set="v1" t-value="'after'"/>
-        <t t-raw="v2"/>
-      </div>`
-    );
-
-    expect(renderToString(qweb, "test")).toBe("<div><span>before</span></div>");
-  });
-
-  test("t-set with t-value (falsy) and body", () => {
-    qweb.addTemplate(
-      "test",
-      `<div>
-        <t t-set="v3" t-value="false"/>
-        <t t-set="v1" t-value="'before'"/>
-        <t t-set="v2" t-value="v3">
-          <span><t t-esc="v1"/></span>
-        </t>
-        <t t-set="v1" t-value="'after'"/>
-        <t t-set="v3" t-value="true"/>
-        <t t-raw="v2"/>
-      </div>`);
-
-      expect(renderToString(qweb, "test")).toBe("<div><span>before</span></div>");
-    });
-
-    test("t-set with t-value (truthy) and body", () => {
-    qweb.addTemplate(
-      "test",
-      `<div>
-        <t t-set="v3" t-value="'Truthy'"/>
-        <t t-set="v1" t-value="'before'"/>
-        <t t-set="v2" t-value="v3">
-          <span><t t-esc="v1"/></span>
-        </t>
-        <t t-set="v1" t-value="'after'"/>
-        <t t-set="v3" t-value="false"/>
-        <t t-raw="v2"/>
-      </div>`);
-
-      expect(renderToString(qweb, "test")).toBe("<div>Truthy</div>");
-    });
 });

 describe("t-if", () => {
@@ -419,61 +328,6 @@ describe("t-if", () => {
    };
    expect(normalize(renderToString(qweb, "test", context))).toBe("<div>andormgtnlt</div>");
  });
-
-  test("t-esc with t-if", () => {
-    qweb.addTemplate("test", `<div><t t-if="true" t-esc="'x'"/></div>`);
-    expect(renderToString(qweb, "test")).toBe("<div>x</div>");
-  });
-
-  test("t-esc with t-elif", () => {
-    qweb.addTemplate("test", `<div><t t-if="false">abc</t><t t-else="1" t-esc="'x'"/></div>`);
-    expect(renderToString(qweb, "test")).toBe("<div>x</div>");
-  });
-
-  test("t-set, then t-if", () => {
-    qweb.addTemplate(
-      "test",
-      `
-      <div>
-        <t t-set="title" t-value="'test'"/>
-        <t t-if="title"><t t-esc="title"/></t>
-      </div>`
-    );
-    const result = renderToString(qweb, "test");
-    const expected = `<div>test</div>`;
-    expect(result).toBe(expected);
-  });
-
-  test("t-set, then t-if, part 2", () => {
-    qweb.addTemplate(
-      "test",
-      `
-        <div>
-            <t t-set="y" t-value="true"/>
-            <t t-set="x" t-value="y"/>
-            <span t-if="x">COUCOU</span>
-        </div>`
-    );
-    const result = renderToString(qweb, "test");
-    const expected = `<div><span>COUCOU</span></div>`;
-    expect(result).toBe(expected);
-  });
-
-  test("t-set, then t-elif, part 3", () => {
-    qweb.addTemplate(
-      "test",
-      `
-        <div>
-            <t t-set="y" t-value="false"/>
-            <t t-set="x" t-value="y"/>
-            <span t-if="x">AAA</span>
-            <span t-elif="!x">BBB</span>
-        </div>`
-    );
-    const result = renderToString(qweb, "test");
-    const expected = `<div><span>BBB</span></div>`;
-    expect(result).toBe(expected);
-  });
 });

 describe("attributes", () => {
@@ -503,18 +357,6 @@ describe("attributes", () => {
    expect(result).toBe(`<div foo="bar"></div>`);
  });

-  test("dynamic class attribute", () => {
-    qweb.addTemplate("test", `<div t-att-class="c"/>`);
-    const result = renderToString(qweb, "test", { c: "abc" });
-    expect(result).toBe(`<div class="abc"></div>`);
-  });
-
-  test("dynamic empty class attribute", () => {
-    qweb.addTemplate("test", `<div t-att-class="c"/>`);
-    const result = renderToString(qweb, "test", { c: "" });
-    expect(result).toBe(`<div></div>`);
-  });
-
  test("dynamic attribute with a dash", () => {
    qweb.addTemplate("test", `<div t-att-data-action-id="id"/>`);
    const result = renderToString(qweb, "test", { id: 32 });
@@ -659,19 +501,10 @@ describe("attributes", () => {

 describe("t-call (template calling", () => {
  test("basic caller", () => {
-    qweb.addTemplate("_basic-callee", "<span>ok</span>");
-    qweb.addTemplate("caller", '<div><t t-call="_basic-callee"/></div>');
-    const expected = "<div><span>ok</span></div>";
-    expect(renderToString(qweb, "caller")).toBe(expected);
-    expect(qweb.subTemplates["_basic-callee"].toString()).toMatchSnapshot();
-  });
-
-  test("basic caller, no parent node", () => {
    qweb.addTemplate("_basic-callee", "<div>ok</div>");
    qweb.addTemplate("caller", '<t t-call="_basic-callee"/>');
    const expected = "<div>ok</div>";
    expect(renderToString(qweb, "caller")).toBe(expected);
-    expect(qweb.subTemplates["_basic-callee"].toString()).toMatchSnapshot();
  });

  test("t-call with t-if", () => {
@@ -679,7 +512,6 @@ describe("t-call (template calling", () => {
    qweb.addTemplate("caller", '<div><t t-if="flag" t-call="sub"/></div>');
    const expected = "<div><span>ok</span></div>";
    expect(renderToString(qweb, "caller", { flag: true })).toBe(expected);
-    expect(qweb.subTemplates["sub"].toString()).toMatchSnapshot();
  });

  test("t-call not allowed on a non t node", () => {
@@ -764,41 +596,6 @@ describe("t-call (template calling", () => {
    `);
    const expected = "<div><div><span>hey</span> <span>yay</span></div></div>";
    expect(renderToString(qweb, "main")).toBe(expected);
-    expect(qweb.subTemplates["SubTemplate"].toString()).toMatchSnapshot();
-  });
-
-  test("cascading t-call t-raw='0'", () => {
-    qweb.addTemplates(`
-        <templates>
-            <div t-name="finalTemplate">
-              <span>cascade 2</span>
-              <t t-raw="0"/>
-            </div>
-
-            <div t-name="subSubTemplate">
-              <t t-call="finalTemplate">
-                <span>cascade 1</span>
-                <t t-raw="0"/>
-              </t>
-            </div>
-
-            <div t-name="SubTemplate">
-              <t t-call="subSubTemplate">
-                <span>cascade 0</span>
-                <t t-raw="0"/>
-              </t>
-            </div>
-
-            <div t-name="main">
-              <t t-call="SubTemplate">
-                <span>hey</span> <span>yay</span>
-              </t>
-            </div>
-        </templates>
-    `);
-    const expected =
-      "<div><div><div><div><span>cascade 2</span><span>cascade 1</span><span>cascade 0</span><span>hey</span> <span>yay</span></div></div></div></div>";
-    expect(renderToString(qweb, "main")).toBe(expected);
  });

  test("recursive template, part 1", () => {
@@ -814,7 +611,7 @@ describe("t-call (template calling", () => {
    `);
    const expected = "<div><span>hey</span></div>";
    expect(renderToString(qweb, "recursive")).toBe(expected);
-    const recursiveFn = Object.values(qweb.subTemplates)[0] as any;
+    const recursiveFn = Object.values(qweb.recursiveFns)[0];
    expect(recursiveFn.toString()).toMatchSnapshot();
  });

@@ -842,7 +639,7 @@ describe("t-call (template calling", () => {
    expect(renderToString(qweb, "Parent", { root }, { fiber: { vars: {}, scope: {} } })).toBe(
      expected
    );
-    const recursiveFn = Object.values(qweb.subTemplates)[0] as any;
+    const recursiveFn = Object.values(qweb.recursiveFns)[0];
    expect(recursiveFn.toString()).toMatchSnapshot();
  });

@@ -869,7 +666,7 @@ describe("t-call (template calling", () => {
    const expected =
      "<div><div><p>a</p><div><p>b</p><div><p>d</p></div></div><div><p>c</p></div></div></div>";
    expect(renderToString(qweb, "Parent", { root }, { fiber: {} })).toBe(expected);
-    const recursiveFn = Object.values(qweb.subTemplates)[0] as any;
+    const recursiveFn = Object.values(qweb.recursiveFns)[0];
    expect(recursiveFn.toString()).toMatchSnapshot();
  });

@@ -879,51 +676,6 @@ describe("t-call (template calling", () => {
    const expected = "<div><span>desk</span></div>";
    expect(trim(renderToString(qweb, "abcd"))).toBe(expected);
  });
-
-  test("t-call with t-set inside and outside", () => {
-    qweb.addTemplates(`
-      <templates>
-        <div t-name="main">
-          <t t-foreach="list" t-as="v">
-            <t t-set="val" t-value="v.val"/>
-            <t t-call="sub">
-              <t t-set="val3" t-value="val*3"/>
-            </t>
-          </t>
-        </div>
-        <t t-name="sub">
-          <span t-esc="val3"/>
-        </t>
-      </templates>
-    `);
-    const expected = "<div><span>3</span><span>6</span><span>9</span></div>";
-    const context = { list: [{ val: 1 }, { val: 2 }, { val: 3 }] };
-    expect(trim(renderToString(qweb, "main", context))).toBe(expected);
-  });
-
-  test("t-call with t-set inside and outside. 2", () => {
-    qweb.addTemplates(`
-      <templates>
-        <div t-name="main">
-          <t t-foreach="list" t-as="v">
-            <t t-set="val" t-value="v.val"/>
-            <t t-call="sub">
-              <t t-set="val3" t-value="val*3"/>
-            </t>
-          </t>
-        </div>
-        <t t-name="sub">
-          <span t-esc="val3"/>
-          <t t-esc="w"/>
-        </t>
-        <p t-name="wrapper"><t t-set="w" t-value="'fromwrapper'"/><t t-call="main"/></p>
-      </templates>
-    `);
-    const expected =
-      "<p><div><span>3</span>fromwrapper<span>6</span>fromwrapper<span>9</span>fromwrapper</div></p>";
-    const context = { list: [{ val: 1 }, { val: 2 }, { val: 3 }] };
-    expect(trim(renderToString(qweb, "wrapper", context))).toBe(expected);
-  });
 });

 describe("foreach", () => {
@@ -992,26 +744,9 @@ describe("foreach", () => {
        <t t-foreach="[1]" t-as="item"><t t-esc="item"/></t>
      </div>`
    );
-    const context = { __owl__: {} };
+    const context = {};
    renderToString(qweb, "test", context);
-    expect(Object.keys(context)).toEqual(["__owl__"]);
-  });
-
-  test("t-foreach in t-forach", () => {
-    qweb.addTemplate(
-      "test",
-      `<div>
-        <t t-foreach="numbers" t-as="number">
-          <t t-foreach="letters" t-as="letter">
-            [<t t-esc="number"/><t t-esc="letter"/>]
-          </t>
-        </t>
-      </div>`
-    );
-    const context = { numbers: [1, 2, 3], letters: ["a", "b"] };
-    expect(renderToString(qweb, "test", context)).toBe(
-      "<div> [1a]  [1b]  [2a]  [2b]  [3a]  [3b] </div>"
-    );
+    expect(Object.keys(context).length).toBe(0);
  });

  test("throws error if invalid loop expression", () => {
@@ -1037,16 +772,13 @@ describe("foreach", () => {
    );
    renderToString(qweb, "test");
    expect(console.warn).toHaveBeenCalledTimes(1);
-    expect(console.warn).toHaveBeenCalledWith(
-      "Directive t-foreach should always be used with a t-key! (in template: 'test')"
-    );
    console.warn = consoleWarn;
  });
 });

 describe("misc", () => {
  test("global", () => {
-    qweb.addTemplate("_callee-asc", `<año t-att-falló="'agüero'" t-raw="0"/>`);
+    qweb.addTemplate("_callee-asc", `<Año t-att-falló="'agüero'" t-raw="0"/>`);
    qweb.addTemplate("_callee-uses-foo", `<span t-esc="foo">foo default</span>`);
    qweb.addTemplate("_callee-asc-toto", `<div t-raw="toto">toto default</div>`);
    qweb.addTemplate(
@@ -1243,35 +975,6 @@ describe("t-on", () => {
    (<HTMLElement>node).click();
  });

-  test("t-on with inline statement", () => {
-    qweb.addTemplate("test", `<button t-on-click="state.counter++">Click</button>`);
-    let owner = {
-      state: {
-        counter: 0
-      }
-    };
-    const node = renderToDOM(qweb, "test", owner, { handlers: [] });
-    expect(owner.state.counter).toBe(0);
-    (<HTMLElement>node).click();
-    expect(owner.state.counter).toBe(1);
-  });
-
-  test("t-on with inline statement (function call)", () => {
-    qweb.addTemplate("test", `<button t-on-click="state.incrementCounter(2)">Click</button>`);
-    let owner = {
-      state: {
-        counter: 0,
-        incrementCounter: inc => {
-          owner.state.counter += inc;
-        }
-      }
-    };
-    const node = renderToDOM(qweb, "test", owner, { handlers: [] });
-    expect(owner.state.counter).toBe(0);
-    (<HTMLElement>node).click();
-    expect(owner.state.counter).toBe(2);
-  });
-
  test("t-on with prevent and/or stop modifiers", async () => {
    expect.assertions(7);
    qweb.addTemplate(
@@ -1383,99 +1086,6 @@ describe("t-on", () => {

    expect(steps).toEqual([true, true]);
  });
-
-  test("t-on with prevent modifier in t-foreach", async () => {
-    expect.assertions(5);
-    qweb.addTemplate(
-      "test",
-      `<div>
-        <t t-foreach="projects" t-as="project">
-          <a href="#" t-key="project" t-on-click.prevent="onEdit(project.id)">
-            Edit <t t-esc="project.name"/>
-          </a>
-        </t>
-      </div>`
-    );
-    const steps: string[] = [];
-    const owner = {
-      projects: [
-        { id: 1, name: "Project 1" },
-        { id: 2, name: "Project 2" }
-      ],
-
-      onEdit(projectId, ev) {
-        expect(ev.defaultPrevented).toBe(true);
-        steps.push(projectId);
-      }
-    };
-
-    const node = <HTMLElement>renderToDOM(qweb, "test", owner, { handlers: [] });
-    expect(node.outerHTML).toBe(
-      `<div><a href="#"> Edit Project 1</a><a href="#"> Edit Project 2</a></div>`
-    );
-
-    const links = node.querySelectorAll("a")!;
-    links[0].click();
-    links[1].click();
-
-    expect(steps).toEqual([1, 2]);
-  });
-
-  test("t-on with empty handler (only modifiers)", () => {
-    expect.assertions(2);
-    qweb.addTemplate(
-      "test",
-      `<div>
-        <button t-on-click.prevent="">Button</button>
-      </div>`
-    );
-    const node = renderToDOM(qweb, "test", {}, { handlers: [] });
-
-    node.addEventListener("click", e => {
-      expect(e.defaultPrevented).toBe(true);
-    });
-
-    const button = (<HTMLElement>node).getElementsByTagName("button")[0];
-    button.click();
-  });
-
-  test("t-on combined with t-esc", async () => {
-    expect.assertions(3);
-    qweb.addTemplate("test", `<div><button t-on-click="onClick" t-esc="text"/></div>`);
-    const steps: string[] = [];
-    const owner = {
-      text: "Click here",
-      onClick() {
-        steps.push("onClick");
-      }
-    };
-
-    const node = <HTMLElement>renderToDOM(qweb, "test", owner, { handlers: [] });
-    expect(node.outerHTML).toBe(`<div><button>Click here</button></div>`);
-
-    node.querySelector("button")!.click();
-
-    expect(steps).toEqual(["onClick"]);
-  });
-
-  test("t-on combined with t-raw", async () => {
-    expect.assertions(3);
-    qweb.addTemplate("test", `<div><button t-on-click="onClick" t-raw="html"/></div>`);
-    const steps: string[] = [];
-    const owner = {
-      html: "Click <b>here</b>",
-      onClick() {
-        steps.push("onClick");
-      }
-    };
-
-    const node = <HTMLElement>renderToDOM(qweb, "test", owner, { handlers: [] });
-    expect(node.outerHTML).toBe(`<div><button>Click <b>here</b></button></div>`);
-
-    node.querySelector("button")!.click();
-
-    expect(steps).toEqual(["onClick"]);
-  });
 });

 describe("t-ref", () => {
@@ -1511,12 +1121,12 @@ describe("t-ref", () => {

 describe("loading templates", () => {
  test("can initialize qweb with a string", () => {
-    const templates = `
+    const data = `
      <?xml version="1.0" encoding="UTF-8"?>
      <templates id="template" xml:space="preserve">
        <div t-name="hey">jupiler</div>
      </templates>`;
-    const qweb = new QWeb({ templates });
+    const qweb = new QWeb(data);
    expect(renderToString(qweb, "hey")).toBe("<div>jupiler</div>");
  });

@@ -1653,22 +1263,6 @@ describe("debugging", () => {
    console.log = consoleLog;
  });

-  test("t-debug on sub template", () => {
-    const consoleLog = console.log;
-    console.log = jest.fn();
-    qweb.addTemplates(`
-      <templates>
-      <p t-name="sub" t-debug="1">coucou</p>
-      <div t-name="test">
-        <t t-call="sub"/>
-      </div>
-      </templates>`);
-    qweb.render("test");
-
-    expect(console.log).toHaveBeenCalledTimes(1);
-    console.log = consoleLog;
-  });
-
  test("t-log", () => {
    const consoleLog = console.log;
    console.log = jest.fn();
@@ -1741,84 +1335,3 @@ describe("properly support svg", () => {
    );
  });
 });
-
-describe("translation support", () => {
-  test("can translate node content", () => {
-    const translations = {
-      word: "mot"
-    };
-    const translateFn = expr => translations[expr] || expr;
-    const qweb = new QWeb({ translateFn });
-    qweb.addTemplate("test", "<div>word</div>");
-    expect(renderToString(qweb, "test")).toBe("<div>mot</div>");
-  });
-
-  test("does not translate node content if disabled", () => {
-    const translations = {
-      word: "mot"
-    };
-    const translateFn = expr => translations[expr] || expr;
-    const qweb = new QWeb({ translateFn });
-    qweb.addTemplate(
-      "test",
-      `
-      <div>
-        <span>word</span>
-        <span t-translation="off">word</span>
-      </div>`
-    );
-    expect(renderToString(qweb, "test")).toBe("<div><span>mot</span><span>word</span></div>");
-  });
-
-  test("some attributes are translated", () => {
-    const translations = {
-      word: "mot"
-    };
-    const translateFn = expr => translations[expr] || expr;
-    const qweb = new QWeb({ translateFn });
-    qweb.addTemplate(
-      "test",
-      `
-      <div>
-        <p label="word">word</p>
-        <p title="word">word</p>
-        <p placeholder="word">word</p>
-        <p alt="word">word</p>
-        <p something="word">word</p>
-      </div>`
-    );
-    expect(renderToString(qweb, "test")).toBe(
-      '<div><p label="mot">mot</p><p title="mot">mot</p><p placeholder="mot">mot</p><p alt="mot">mot</p><p something="word">mot</p></div>'
-    );
-  });
-});
-
-describe("t-key tests", () => {
-  test("t-key on t-foreach", async () => {
-    qweb.addTemplate(
-      "test",
-      `
-        <div>
-          <t t-foreach="things" t-as="thing" t-key="thing">
-            <span/>
-          </t>
-        </div>`
-    );
-
-    let vnode = qweb.render("test", { things: [1, 2] });
-    vnode = patch(document.createElement("div"), vnode);
-    let elm = vnode.elm as HTMLElement;
-
-    expect(elm.outerHTML).toBe("<div><span></span><span></span></div>");
-
-    const first = elm.querySelectorAll("span")[0];
-    const second = elm.querySelectorAll("span")[1];
-
-    patch(vnode, qweb.render("test", { things: [2, 1] }));
-
-    expect(elm.outerHTML).toBe("<div><span></span><span></span></div>");
-
-    expect(first).toBe(elm.querySelectorAll("span")[1]);
-    expect(second).toBe(elm.querySelectorAll("span")[0]);
-  });
-});
@@ -27,10 +27,7 @@ describe("tokenizer", () => {
      { type: "VALUE", value: "2" },
      { type: "RIGHT_BRACE", value: "}" }
    ]);
-    expect(tokenize("a,")).toEqual([
-      { type: "SYMBOL", value: "a" },
-      { type: "COMMA", value: "," }
-    ]);
+    expect(tokenize("a,")).toEqual([{ type: "SYMBOL", value: "a" }, { type: "COMMA", value: "," }]);
    expect(tokenize("][")).toEqual([
      { type: "RIGHT_BRACKET", value: "]" },
      { type: "LEFT_BRACKET", value: "[" }
@@ -46,10 +43,6 @@ describe("tokenizer", () => {
      { type: "OPERATOR", value: "!==" },
      { type: "OPERATOR", value: "!=" }
    ]);
-    expect(tokenize("typeof a")).toEqual([
-      { type: "OPERATOR", value: "typeof " },
-      { type: "SYMBOL", value: "a" }
-    ]);
  });

  test("strings", () => {
@@ -92,7 +85,7 @@ describe("expression evaluation", () => {

  test("parenthesis", () => {
    expect(compileExpr("(1)", {})).toBe("(1)");
-    expect(compileExpr("a*(1 +3)", {})).toBe("scope['a']*(1+3)");
+    expect(compileExpr("a*(1 +3)", {})).toBe("context['a']*(1+3)");
  });

  test("objects and sub objects", () => {
@@ -100,8 +93,8 @@ describe("expression evaluation", () => {
  });

  test("replacing variables", () => {
-    expect(compileExpr("a", {})).toBe("scope['a']");
-    expect(compileExpr("a", { a: { id: "_3", expr: "scope._3" } })).toBe("scope._3");
+    expect(compileExpr("a", {})).toBe("context['a']");
+    expect(compileExpr("a", { a: { id: "_3", expr: "" } })).toBe("_3");
  });

  test("arrays and objects", () => {
@@ -111,63 +104,55 @@ describe("expression evaluation", () => {
  });

  test("dot operator", () => {
-    expect(compileExpr("a.b", {})).toBe("scope['a'].b");
-    expect(compileExpr("a.b.c", {})).toBe("scope['a'].b.c");
+    expect(compileExpr("a.b", {})).toBe("context['a'].b");
+    expect(compileExpr("a.b.c", {})).toBe("context['a'].b.c");
  });

  test("various unary operators", () => {
-    expect(compileExpr("!flag", {})).toBe("!scope['flag']");
+    expect(compileExpr("!flag", {})).toBe("!context['flag']");
    expect(compileExpr("-3", {})).toBe("-3");
-    expect(compileExpr("-a", {})).toBe("-scope['a']");
-    expect(compileExpr("typeof a", {})).toBe("typeof scope['a']");
+    expect(compileExpr("-a", {})).toBe("-context['a']");
  });

  test("various binary operators", () => {
-    expect(compileExpr("color == 'black'", {})).toBe("scope['color']=='black'");
-    expect(compileExpr("a || b", {})).toBe("scope['a']||scope['b']");
-    expect(compileExpr("color === 'black'", {})).toBe("scope['color']==='black'");
-    expect(compileExpr("'li_'+item", {})).toBe("'li_'+scope['item']");
-    expect(compileExpr("state.val > 1", {})).toBe("scope['state'].val>1");
+    expect(compileExpr("color == 'black'", {})).toBe("context['color']=='black'");
+    expect(compileExpr("a || b", {})).toBe("context['a']||context['b']");
+    expect(compileExpr("color === 'black'", {})).toBe("context['color']==='black'");
+    expect(compileExpr("'li_'+item", {})).toBe("'li_'+context['item']");
+    expect(compileExpr("state.val > 1", {})).toBe("context['state'].val>1");
  });

  test("boolean operations", () => {
-    expect(compileExpr("a && b", {})).toBe("scope['a']&&scope['b']");
+    expect(compileExpr("a && b", {})).toBe("context['a']&&context['b']");
  });

  test("ternary operators", () => {
-    expect(compileExpr("a ? b: '2'", {})).toBe("scope['a']?scope['b']:'2'");
-    expect(compileExpr("a ? b: (c or '2') ", {})).toBe("scope['a']?scope['b']:(scope['c']||'2')");
+    expect(compileExpr("a ? b: '2'", {})).toBe("context['a']?context['b']:'2'");
+    expect(compileExpr("a ? b: (c or '2') ", {})).toBe(
+      "context['a']?context['b']:(context['c']||'2')"
+    );
    expect(compileExpr("a ? {test:c}: [1,u]", {})).toBe(
-      "scope['a']?{test:scope['c']}:[1,scope['u']]"
+      "context['a']?{test:context['c']}:[1,context['u']]"
    );
  });

  test("word replacement", () => {
-    expect(compileExpr("a or b", {})).toBe("scope['a']||scope['b']");
-    expect(compileExpr("a and b", {})).toBe("scope['a']&&scope['b']");
+    expect(compileExpr("a or b", {})).toBe("context['a']||context['b']");
+    expect(compileExpr("a and b", {})).toBe("context['a']&&context['b']");
  });

  test("function calls", () => {
-    expect(compileExpr("a()", {})).toBe("scope['a']()");
-    expect(compileExpr("a(1)", {})).toBe("scope['a'](1)");
-    expect(compileExpr("a(1,2)", {})).toBe("scope['a'](1,2)");
-    expect(compileExpr("a(1,2,{a:[a]})", {})).toBe("scope['a'](1,2,{a:[scope['a']]})");
+    expect(compileExpr("a()", {})).toBe("context['a']()");
+    expect(compileExpr("a(1)", {})).toBe("context['a'](1)");
+    expect(compileExpr("a(1,2)", {})).toBe("context['a'](1,2)");
+    expect(compileExpr("a(1,2,{a:[a]})", {})).toBe("context['a'](1,2,{a:[context['a']]})");
    expect(compileExpr("'x'.toUpperCase()", {})).toBe("'x'.toUpperCase()");
    expect(compileExpr("'x'.toUpperCase({a: 3})", {})).toBe("'x'.toUpperCase({a:3})");
-    expect(compileExpr("'x'.toUpperCase(a)", { a: { id: "_v5", expr: "scope._v5" } })).toBe(
-      "'x'.toUpperCase(scope._v5)"
+    expect(compileExpr("'x'.toUpperCase(a)", { a: { id: "_v5", expr: "" } })).toBe(
+      "'x'.toUpperCase(_v5)"
    );
-    expect(compileExpr("'x'.toUpperCase({b: a})", { a: { id: "_v5", expr: "scope._v5" } })).toBe(
-      "'x'.toUpperCase({b:scope._v5})"
-    );
-  });
-
-  test("arrow functions", () => {
-    expect(compileExpr("list.map(e => e.val)", {})).toBe("scope['list'].map(e=>e.val)");
-    expect(compileExpr("list.map(e => a + e)", {})).toBe("scope['list'].map(e=>scope['a']+e)");
-    expect(compileExpr("list.map((e) => e)", {})).toBe("scope['list'].map((e)=>e)");
-    expect(compileExpr("list.map((elem, index) => elem + index)", {})).toBe(
-      "scope['list'].map((elem,index)=>elem+index)"
+    expect(compileExpr("'x'.toUpperCase({b: a})", { a: { id: "_v5", expr: "" } })).toBe(
+      "'x'.toUpperCase({b:_v5})"
    );
  });
 });
@@ -1,8 +1,8 @@
 import { Component } from "../../src/component/component";
-import { Link } from "../../src/router/link";
-import { RouterEnv } from "../../src/router/router";
+import { Link } from "../../src/router/Link";
+import { RouterEnv } from "../../src/router/Router";
 import { makeTestEnv, makeTestFixture, nextTick } from "../helpers";
-import { TestRouter } from "./test_router";
+import { TestRouter } from "./TestRouter";

 describe("Link component", () => {
  let fixture: HTMLElement;
@@ -12,7 +12,6 @@ describe("Link component", () => {
  beforeEach(() => {
    fixture = makeTestFixture();
    env = <RouterEnv>makeTestEnv();
-    Component.env = env;
  });

  afterEach(() => {
@@ -35,14 +34,11 @@ describe("Link component", () => {
      static components = { Link: Link };
    }

-    const routes = [
-      { name: "about", path: "/about" },
-      { name: "users", path: "/users" }
-    ];
+    const routes = [{ name: "about", path: "/about" }, { name: "users", path: "/users" }];

    router = new TestRouter(env, routes, { mode: "history" });
    router.navigate({ to: "users" });
-    const app = new App();
+    const app = new App(env);
    await app.mount(fixture);
    expect(fixture.innerHTML).toBe('<div><a href="/about">About</a></div>');

@@ -69,14 +65,11 @@ describe("Link component", () => {
      static components = { Link: Link };
    }

-    const routes = [
-      { name: "about", path: "/about" },
-      { name: "users", path: "/users" }
-    ];
+    const routes = [{ name: "about", path: "/about" }, { name: "users", path: "/users" }];

    router = new TestRouter(env, routes, { mode: "history" });
    router.navigate({ to: "users" });
-    const app = new App();
+    const app = new App(env);
    await app.mount(fixture);

    expect(window.location.pathname).toBe("/users");
@@ -1,8 +1,8 @@
 import { Component } from "../../src/component/component";
-import { RouterEnv } from "../../src/router/router";
-import { RouteComponent } from "../../src/router/route_component";
+import { RouterEnv } from "../../src/router/Router";
+import { RouteComponent } from "../../src/router/RouteComponent";
 import { makeTestEnv, makeTestFixture, nextTick } from "../helpers";
-import { TestRouter } from "./test_router";
+import { TestRouter } from "./TestRouter";

 describe("RouteComponent", () => {
  let fixture: HTMLElement;
@@ -12,7 +12,6 @@ describe("RouteComponent", () => {
  beforeEach(() => {
    fixture = makeTestFixture();
    env = <RouterEnv>makeTestEnv();
-    Component.env = env;
  });

  afterEach(() => {
@@ -46,7 +45,7 @@ describe("RouteComponent", () => {

    router = new TestRouter(env, routes, { mode: "history" });
    await router.navigate({ to: "about" });
-    const app = new App();
+    const app = new App(env);
    await app.mount(fixture);
    expect(fixture.innerHTML).toBe("<div><span>About</span></div>");

@@ -73,7 +72,7 @@ describe("RouteComponent", () => {
    const routes = [{ name: "book", path: "/book/{{title}}", component: Book }];
    router = new TestRouter(env, routes, { mode: "history" });
    await router.navigate({ to: "book", params: { title: "1984" } });
-    const app = new App();
+    const app = new App(env);
    await app.mount(fixture);
    expect(fixture.innerHTML).toBe("<div><span>Book 1984</span></div>");
  });
@@ -99,7 +98,7 @@ describe("RouteComponent", () => {
    const routes = [{ name: "book", path: "/book/{{title}}/{{val.number}}", component: Book }];
    router = new TestRouter(env, routes, { mode: "history" });
    await router.navigate({ to: "book", params: { title: "1984", val: "123" } });
-    const app = new App();
+    const app = new App(env);
    await app.mount(fixture);
    expect(fixture.innerHTML).toBe("<div><span>Book 1984|124</span></div>");
  });
@@ -1,4 +1,4 @@
-import { Router } from "../../src/router/router";
+import { Router } from "../../src/router/Router";
 import { QWeb } from "../../src/qweb/index";

 export class TestRouter extends Router {
@@ -0,0 +1,25 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`Link component can render simple cases 1`] = `
+"function anonymous(context,extra
+) {
+    let utils = this.constructor.utils;
+    let owner = context;
+    var h = this.h;
+    let _1 = utils.toObj({'router-link-active':context['isActive']});
+    var _2 = context['href'];
+    let c3 = [], p3 = {key:3,attrs:{href: _2},class:_1,on:{}};
+    var vn3 = h('a', p3, c3);
+    result = vn3;
+    if (!context['navigate']) {
+        throw new Error('Missing handler \\\\'' + 'navigate' + \`\\\\' when evaluating template '__template__1'\`)
+    }
+    extra.handlers['click' + 3] = extra.handlers['click' + 3] || context['navigate'].bind(owner);
+    p3.on['click'] = extra.handlers['click' + 3];
+    const slot4 = this.constructor.slots[context.__owl__.slotId + '_' + 'default'];
+    if (slot4) {
+        slot4.call(this, context.__owl__.parent, Object.assign({}, extra, {parentNode: c3, vars: extra.vars, parent: owner}));
+    }
+    return vn3;
+}"
+`;
@@ -0,0 +1,45 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`RouteComponent can render simple cases 1`] = `
+"function anonymous(context,extra
+) {
+    let utils = this.constructor.utils;
+    let QWeb = this.constructor;
+    let parent = context;
+    let owner = context;
+    let result;
+    var h = this.h;
+    if (context['routeComponent']) {
+        //COMPONENT
+        let key4 = 'key' + context['env'].router.currentRouteName;
+        let def2;
+        let templateId5 = key4;
+        let w3 = templateId5 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[templateId5]] : false;
+        let vn6 = {};
+        result = vn6;
+        let props3 = Object.assign({}, context['env'].router.currentParams);
+        if (w3 && w3.__owl__.currentFiber && !w3.__owl__.vnode) {
+            if (utils.shallowEqual(props3, w3.__owl__.currentFiber.props)) {
+                def2 = w3.__owl__.currentFiber.promise;
+            } else {
+                w3.destroy();
+                w3 = false;
+            }
+        }
+        if (!w3) {
+            let componentKey3 = \`routeComponent\`;
+            let W3 = context.constructor.components[componentKey3] || QWeb.components[componentKey3]|| context['routeComponent'];
+            if (!W3) {throw new Error('Cannot find the definition of component \\"' + componentKey3 + '\\"')}
+            w3 = new W3(parent, props3);
+            parent.__owl__.cmap[templateId5] = w3.__owl__.id;
+            def2 = w3.__prepare(extra.fiber, undefined, undefined);
+            def2 = def2.then(vnode=>{if (w3.__owl__.isDestroyed){return}let pvnode=h(vnode.sel, {key: templateId5, hook: {insert(vn) {let nvn=w3.__mount(vnode, pvnode.elm);pvnode.elm=nvn.elm;},remove() {},destroy(vn) {w3.destroy();}}});utils.defineProxy(vn6, pvnode);w3.__owl__.pvnode = pvnode;});
+        } else {
+            def2 = def2 || w3.__updateProps(props3, extra.fiber, undefined, undefined);
+            def2 = def2.then(()=>{if (w3.__owl__.isDestroyed) {return};let pvnode=w3.__owl__.pvnode;utils.defineProxy(vn6, pvnode);});
+        }
+        extra.promises.push(def2);
+    }
+    return result;
+}"
+`;
@@ -1,22 +0,0 @@
-// Jest Snapshot v1, https://goo.gl/fbAQLP
-
-exports[`Link component can render simple cases 1`] = `
-"function anonymous(context, extra
-) {
-    // Template name: \\"__template__1\\"
-    let utils = this.constructor.utils;
-    let scope = Object.create(context);
-    var h = this.h;
-    let _5 = utils.toObj({'router-link-active':scope['isActive']});
-    var _6 = scope['href'];
-    let c7 = [], p7 = {key:7,attrs:{href: _6},class:_5,on:{}};
-    var vn7 = h('a', p7, c7);
-    extra.handlers['click' + 7] = extra.handlers['click' + 7] || function (e) {if (!context.__owl__.isMounted){return}const fn = context['navigate'];if (fn) { fn.call(context, e); } else { context.navigate; }};
-    p7.on['click'] = extra.handlers['click' + 7];
-    const slot8 = this.constructor.slots[context.__owl__.slotId + '_' + 'default'];
-    if (slot8) {
-        slot8.call(this, context.__owl__.scope, Object.assign({}, extra, {parentNode: c7, parent: extra.parent || context}));
-    }
-    return vn7;
-}"
-`;
@@ -1,44 +0,0 @@
-// Jest Snapshot v1, https://goo.gl/fbAQLP
-
-exports[`RouteComponent can render simple cases 1`] = `
-"function anonymous(context, extra
-) {
-    // Template name: \\"__template__1\\"
-    let utils = this.constructor.utils;
-    let QWeb = this.constructor;
-    let parent = context;
-    let scope = Object.create(context);
-    let result;
-    var h = this.h;
-    if (scope['routeComponent']) {
-        const nodeKey5 = scope['env'].router.currentRouteName;
-        //COMPONENT
-        let k7 = \`__8__\` + nodeKey5;
-        let w6 = k7 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[k7]] : false;
-        let vn9 = {};
-        result = vn9;
-        let props6 = Object.assign({}, scope['env'].router.currentParams);
-        if (w6 && w6.__owl__.currentFiber && !w6.__owl__.vnode) {
-            w6.destroy();
-            w6 = false;
-        }
-        if (w6) {
-            w6.__updateProps(props6, extra.fiber, undefined);
-            let pvnode = w6.__owl__.pvnode;
-            utils.defineProxy(vn9, pvnode);
-        } else {
-            let componentKey6 = \`routeComponent\`;
-            let W6 = context.constructor.components[componentKey6] || QWeb.components[componentKey6]|| scope['routeComponent'];
-            if (!W6) {throw new Error('Cannot find the definition of component \\"' + componentKey6 + '\\"')}
-            w6 = new W6(parent, props6);
-            parent.__owl__.cmap[k7] = w6.__owl__.id;
-            let fiber = w6.__prepare(extra.fiber, undefined, () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
-            let pvnode = h('dummy', {key: k7, hook: {remove() {},destroy(vn) {w6.destroy();}}});
-            utils.defineProxy(vn9, pvnode);
-            w6.__owl__.pvnode = pvnode;
-        }
-        w6.__owl__.parentLastFiberId = extra.fiber.id;
-    }
-    return result;
-}"
-`;
@@ -1,6 +1,6 @@
-import { Destination, RouterEnv, Route } from "../../src/router/router";
+import { Destination, RouterEnv, Route } from "../../src/router/Router";
 import { makeTestEnv, nextTick } from "../helpers";
-import { TestRouter } from "./test_router";
+import { TestRouter } from "./TestRouter";

 let env: RouterEnv;
 let router: TestRouter | null = null;
@@ -52,14 +52,6 @@ describe("router miscellaneous", () => {
    expect(window.location.hash).toBe("#/users/5");
    expect(env.qweb.forceUpdate).toHaveBeenCalledTimes(2);
  });
-
-  test("navigate in hash mode preserve location", async () => {
-    router = new TestRouter(env, [{ name: "users", path: "/users/{{id}}" }], { mode: "hash" });
-    window.history.pushState({}, "title", window.location.origin + "/test.html");
-    expect(window.location.href).toBe("http://localhost/test.html");
-    await router.navigate({ to: "users", params: { id: 3 } });
-    expect(window.location.href).toBe("http://localhost/test.html#/users/3");
-  });
 });

 describe("routeToPath", () => {
@@ -0,0 +1,21 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`connecting a component to store connecting a component to a local store 1`] = `"<div></div>"`;
+
+exports[`connecting a component to store connecting a component to a local store 2`] = `"<div><span>hello</span></div>"`;
+
+exports[`connecting a component to store connecting a component works 1`] = `"<div></div>"`;
+
+exports[`connecting a component to store connecting a component works 2`] = `"<div><span>hello</span></div>"`;
+
+exports[`connecting a component to store deep and shallow connecting a component 1`] = `"<div><span>Kasteel</span></div>"`;
+
+exports[`connecting a component to store deep and shallow connecting a component 2`] = `"<div><span>Kasteel</span></div>"`;
+
+exports[`connecting a component to store deep and shallow connecting a component 3`] = `"<div><span>Bertinchamps</span></div>"`;
+
+exports[`connecting a component to store deep and shallow connecting a component 4`] = `"<div><span>Kasteel</span></div>"`;
+
+exports[`various scenarios scenarios with async store updates and some components events 1`] = `"<div><button>Do stuff</button><div><span>Attachment 100</span><span>Name: text.txt</span></div></div>"`;
+
+exports[`various scenarios scenarios with async store updates and some components events 2`] = `"<div><button>Do stuff</button></div>"`;
@@ -1,6 +1,6 @@
-import { Env } from "../src/component/component";
-import { Store, Getter } from "../src/store";
-import { nextTick, nextMicroTick } from "./helpers";
+import { Env } from "../../src/component/component";
+import { Store, Getter } from "../../src/store/store";
+import { nextTick, nextMicroTick } from "../helpers";

 describe("basic use", () => {
  test("dispatch an action", () => {
@@ -1,57 +0,0 @@
-/**
- * We can only make one test per file, since the debug tool modify in place
- * the owl object in a way that is difficult to undo.
- */
-
-import { debugOwl } from "../../tools/debug";
-import * as owl from "../../src/index";
-
-import { Component, Env } from "../../src/component/component";
-import { xml } from "../../src/tags";
-import { useState } from "../../src/hooks";
-import { makeTestFixture, makeTestEnv, nextTick } from "../helpers";
-
-let fixture: HTMLElement = makeTestFixture();
-let env: Env = makeTestEnv();
-Component.env = env;
-
-debugOwl(owl, {});
-
-test("can log full lifecycle", async () => {
-  const steps: string[] = [];
-  const log = console.log;
-  console.log = arg => steps.push(arg);
-
-  class Child extends Component<any, any> {
-    static template = xml`<div>child</div>`;
-  }
-
-  class Parent extends Component<any, any> {
-    static template = xml`<div><Child t-if="state.flag"/></div>`;
-    static components = { Child };
-    state = useState({ flag: false });
-  }
-
-  const parent = new Parent(null, {});
-  await parent.mount(fixture);
-
-  parent.state.flag = true;
-  await nextTick();
-
-  expect(steps).toEqual([
-    "[OWL_DEBUG] Parent<id=1> constructor, props={}",
-    "[OWL_DEBUG] Parent<id=1> mount",
-    "[OWL_DEBUG] Parent<id=1> willStart",
-    "[OWL_DEBUG] Parent<id=1> rendering template",
-    "[OWL_DEBUG] Parent<id=1> mounted",
-    "[OWL_DEBUG] Parent<id=1> render",
-    "[OWL_DEBUG] Parent<id=1> rendering template",
-    "[OWL_DEBUG] Child<id=2> constructor, props={}",
-    "[OWL_DEBUG] Child<id=2> willStart",
-    "[OWL_DEBUG] Child<id=2> rendering template",
-    "[OWL_DEBUG] Parent<id=1> willPatch",
-    "[OWL_DEBUG] Child<id=2> mounted",
-    "[OWL_DEBUG] Parent<id=1> patched"
-  ]);
-  console.log = log;
-});
@@ -1,50 +0,0 @@
-/**
- * We can only make one test per file, since the debug tool modify in place
- * the owl object in a way that is difficult to undo.
- */
-
-import { debugOwl } from "../../tools/debug";
-import * as owl from "../../src/index";
-
-import { Component, Env } from "../../src/component/component";
-import { xml } from "../../src/tags";
-import { makeTestFixture, makeTestEnv } from "../helpers";
-
-let fixture: HTMLElement = makeTestFixture();
-let env: Env = makeTestEnv();
-Component.env = env;
-
-debugOwl(owl, { logScheduler: true });
-
-test("can log scheduler start and stop", async () => {
-  const steps: string[] = [];
-  const log = console.log;
-  console.log = arg => steps.push(arg);
-
-  class Child extends Component<any, any> {
-    static template = xml`<div>child</div>`;
-  }
-
-  class Parent extends Component<any, any> {
-    static template = xml`<div><Child /></div>`;
-    static components = { Child };
-  }
-
-  const parent = new Parent(null, {});
-  await parent.mount(fixture);
-
-  expect(steps).toEqual([
-    "[OWL_DEBUG] Parent<id=1> constructor, props={}",
-    "[OWL_DEBUG] Parent<id=1> mount",
-    "[OWL_DEBUG] Parent<id=1> willStart",
-    "[OWL_DEBUG] scheduler: start running tasks queue",
-    "[OWL_DEBUG] Parent<id=1> rendering template",
-    "[OWL_DEBUG] Child<id=2> constructor, props={}",
-    "[OWL_DEBUG] Child<id=2> willStart",
-    "[OWL_DEBUG] Child<id=2> rendering template",
-    "[OWL_DEBUG] Child<id=2> mounted",
-    "[OWL_DEBUG] Parent<id=1> mounted",
-    "[OWL_DEBUG] scheduler: stop running tasks queue"
-  ]);
-  console.log = log;
-});
@@ -1,46 +0,0 @@
-/**
- * We can only make one test per file, since the debug tool modify in place
- * the owl object in a way that is difficult to undo.
- */
-
-import { debugOwl } from "../../tools/debug";
-import * as owl from "../../src/index";
-
-import { Component, Env } from "../../src/component/component";
-import { xml } from "../../src/tags";
-import { makeTestFixture, makeTestEnv } from "../helpers";
-
-let fixture: HTMLElement = makeTestFixture();
-let env: Env = makeTestEnv();
-Component.env = env;
-
-debugOwl(owl, { logScheduler: true });
-
-test("log a specific message for render method calls if component is not mounted", async () => {
-  const steps: string[] = [];
-  const log = console.log;
-  console.log = arg => steps.push(arg);
-
-  class Parent extends Component<any, any> {
-    static template = xml`<div><t t-esc="state.value"/></div>`;
-    state = owl.hooks.useState({ value: 1 });
-  }
-
-  const parent = new Parent(null, {});
-  await parent.mount(fixture);
-  parent.unmount();
-  parent.state.value = 2;
-
-  expect(steps).toEqual([
-    "[OWL_DEBUG] Parent<id=1> constructor, props={}",
-    "[OWL_DEBUG] Parent<id=1> mount",
-    "[OWL_DEBUG] Parent<id=1> willStart",
-    "[OWL_DEBUG] scheduler: start running tasks queue",
-    "[OWL_DEBUG] Parent<id=1> rendering template",
-    "[OWL_DEBUG] Parent<id=1> mounted",
-    "[OWL_DEBUG] scheduler: stop running tasks queue",
-    "[OWL_DEBUG] Parent<id=1> willUnmount",
-    "[OWL_DEBUG] Parent<id=1> render (warning: component is not mounted, this render has no effect)"
-  ]);
-  console.log = log;
-});
@@ -1,183 +0,0 @@
-/**
- * Doc Link Checker
- *
- * We define here a test to make sure that there are no dead link in the Owl
- * documentation.
- */
-import * as fs from "fs";
-
-//--------------------------------------------------------------------------
-// Helpers
-//--------------------------------------------------------------------------
-
-interface MarkDownLink {
-  name: string;
-  link: string;
-}
-
-interface MarkDownSection {
-  name: string;
-  slug: string;
-}
-
-interface FileData {
-  name: string;
-  path: string[];
-  fullName: string;
-  links: MarkDownLink[];
-  sections: MarkDownSection[];
-}
-
-const LINK_REGEXP = /\[([^\[]+)\]\(([^\)]+)\)/g;
-const HEADING_REGEXP = /\n(#+\s*)(.*)/g;
-
-export function addMardownData(fileData): void {
-  const sep = fileData.path.length > 0 ? "/" : "";
-  const fullName = fileData.path.join("/") + sep + fileData.name;
-  const content = fs.readFileSync(fullName, { encoding: "utf8" });
-  let m;
-  // get links info
-  do {
-    m = LINK_REGEXP.exec(content);
-    if (m) {
-      fileData.links.push({ name: m[0], link: m[2] });
-    }
-  } while (m);
-  // get sections info
-  do {
-    m = HEADING_REGEXP.exec(content);
-    if (m) {
-      fileData.sections.push({ name: m[0], slug: slugify(m[2]) });
-    }
-  } while (m);
-}
-
-/**
- * Returns a list of FileData corresponding to all files that need to be
- * validated.
- */
-function getFiles(path: string[] = []): FileData[] {
-  if (path.length === 0) {
-    const baseFiles: FileData[] = [
-      { name: "README.md", path: [], links: [], sections: [], fullName: "README.md" },
-      { name: "roadmap.md", path: [], links: [], sections: [], fullName: "roadmap.md" }
-    ];
-    const rest = getFiles(["doc"]);
-    const result = baseFiles.concat(rest);
-    result.forEach(addMardownData);
-    return result;
-  }
-  const files = fs.readdirSync(path.join("/"), { withFileTypes: true }).map(f => {
-    if (f.isDirectory()) {
-      return getFiles(path.concat(f.name));
-    }
-    const fullName = path.join("/") + (path.length > 0 ? "/" : "") + f.name;
-    return [
-      {
-        name: f.name,
-        path,
-        links: [],
-        sections: [],
-        fullName
-      }
-    ];
-  });
-  return Array.prototype.concat(...files);
-}
-
-const LOCAL_FILES = ["LICENSE", "tools/debug.js"];
-export function isLinkValid(link: MarkDownLink, current: FileData, files: FileData[]): boolean {
-  if (link.link.startsWith("http")) {
-    // no check on external links
-    return true;
-  }
-  // Step 1: extract path, name, hash
-  //      path = ['doc', 'architecture]
-  //      name = 'rendering.md'
-  //      hash = 'blabla' (or '' if no hash)
-
-  const parts = link.link.split("#");
-  const hash = parts[1] || "";
-  let name;
-  let path;
-  if (parts[0]) {
-    let temp = parts[0].split("/");
-    name = temp[temp.length - 1];
-    temp.splice(-1);
-    path = current.path.slice();
-    for (let elem of temp) {
-      if (elem === "..") {
-        path.splice(-1);
-      } else if (elem !== ".") {
-        path.push(elem);
-      }
-    }
-  } else {
-    // there are no file name, so this is a relative link to the current file
-    name = current.name;
-    path = current.path;
-  }
-
-  // Step 2: build normalized link file name
-  const linkFullName = path.join("/") + (path.length > 0 ? "/" : "") + name;
-
-  // Step 3: check link name against white list of local files
-  if (LOCAL_FILES.includes(linkFullName)) {
-    return true;
-  }
-
-  // Step 4: check if there is a matching file
-  let target: FileData | undefined = files.find(f => f.fullName === linkFullName);
-  if (!target) {
-    return false;
-  }
-
-  // Step 5: if necessary, check if there is a corresponding link inside the target
-  // link name
-  if (hash) {
-    if (!target.sections.find(s => s.slug === hash)) {
-      return false;
-    }
-  }
-
-  return true;
-}
-
-// adapted from https://medium.com/@mhagemann/the-ultimate-way-to-slugify-a-url-string-in-javascript-b8e4a0d849e1
-function slugify(str) {
-  const a = "àáäâãåăæçèéëêǵḧìíïîḿńǹñòóöôœøṕŕßśșțùúüûǘẃẍÿź·_,:;";
-  const b = "aaaaaaaaceeeeghiiiimnnnooooooprssstuuuuuwxyz-----";
-  const p = new RegExp(a.split("").join("|"), "g");
-  return str
-    .toString()
-    .toLowerCase()
-    .replace(/\//g, "") // remove /
-    .replace(/\s+/g, "-") // Replace spaces with -
-    .replace(p, c => b.charAt(a.indexOf(c))) // Replace special characters
-    .replace(/&/g, "-and-") // Replace & with ‘and’
-    .replace(/[^\w\-]+/g, "") // Remove all non-word characters
-    .replace(/\-\-+/g, "-") // Replace multiple - with single -
-    .replace(/^-+/, "") // Trim - from start of text
-    .replace(/-+$/, ""); // Trim - from end of text
-}
-
-//--------------------------------------------------------------------------
-// Test
-//--------------------------------------------------------------------------
-
-test("All markdown links work", () => {
-  let linkNumber = 0;
-  let invalidLinkNumber = 0;
-  const data = getFiles();
-  for (let file of data) {
-    for (let link of file.links) {
-      linkNumber++;
-      if (!isLinkValid(link, file, data)) {
-        console.warn(`Invalid Link: "${link.name}" in "${file.name}"`);
-        invalidLinkNumber++;
-      }
-    }
-  }
-  expect(invalidLinkNumber).toBe(0);
-  expect(linkNumber).toBeGreaterThan(10);
-});
@@ -1,5 +1,4 @@
 import { h, patch } from "../src/vdom";
-import { htmlToVDOM } from "../src/vdom/html_to_vdom";
 import { init, addNS } from "../src/vdom/vdom";

 function map(list, fn) {
@@ -185,6 +184,20 @@ describe("snabbdom", function() {
      expect(elm.tagName).toBe("DIV");
    });

+    test("has different tag and id", function() {
+      let elm: any = document.createElement("div");
+      vnode0.appendChild(elm);
+      const vnode1 = h("span#id");
+      elm = patch(elm, vnode1).elm;
+      expect(elm.tagName).toBe("SPAN");
+      expect(elm.id).toBe("id");
+    });
+
+    test("has id", function() {
+      elm = patch(vnode0, h("div", [h("div#unique")])).elm;
+      expect(elm.firstChild.id).toBe("unique");
+    });
+
    test("has correct namespace", function() {
      const SVGNamespace = "http://www.w3.org/2000/svg";
      const XHTMLNamespace = "http://www.w3.org/1999/xhtml";
@@ -204,6 +217,20 @@ describe("snabbdom", function() {
      expect(elm.firstChild.firstChild.namespaceURI).toBe(XHTMLNamespace);
    });

+    test("receives classes in selector", function() {
+      elm = patch(vnode0, h("div", [h("i.am.a.class")])).elm;
+      expect(elm.firstChild.classList.contains("am")).toBeTruthy();
+      expect(elm.firstChild.classList.contains("a")).toBeTruthy();
+      expect(elm.firstChild.classList.contains("class")).toBeTruthy();
+    });
+
+    test("receives classes in selector when namespaced", function() {
+      elm = patch(vnode0, h("svg", [h("g.am.a.class.too")])).elm;
+      expect(elm.firstChild.classList.contains("am")).toBeTruthy();
+      expect(elm.firstChild.classList.contains("a")).toBeTruthy();
+      expect(elm.firstChild.classList.contains("class")).toBeTruthy();
+    });
+
    test("can create elements with text content", function() {
      elm = patch(vnode0, h("div", ["I am a string"])).elm;
      expect(elm.innerHTML).toBe("I am a string");
@@ -240,6 +267,26 @@ describe("snabbdom", function() {
  });

  describe("patching an element", function() {
+    test("changes the elements classes", function() {
+      const vnode1 = h("i.i.am.horse");
+      const vnode2 = h("i.i.am");
+      patch(vnode0, vnode1);
+      elm = patch(vnode1, vnode2).elm;
+      expect(elm.classList.contains("i")).toBeTruthy();
+      expect(elm.classList.contains("am")).toBeTruthy();
+      expect(!elm.classList.contains("horse")).toBeTruthy();
+    });
+
+    test("removes missing classes", function() {
+      const vnode1 = h("i.i.am.horse");
+      const vnode2 = h("i.i.am");
+      patch(vnode0, vnode1);
+      elm = patch(vnode1, vnode2).elm;
+      expect(elm.classList.contains("i")).toBeTruthy();
+      expect(elm.classList.contains("am")).toBeTruthy();
+      expect(!elm.classList.contains("horse")).toBeTruthy();
+    });
+
    test("changes an elements props", function() {
      const vnode1 = h("a", { props: { src: "http://other/" } });
      const vnode2 = h("a", { props: { src: "http://localhost/" } });
@@ -1057,52 +1104,3 @@ describe("snabbdom", function() {
    });
  });
 });
-
-//------------------------------------------------------------------------------
-// Html to vdom
-//------------------------------------------------------------------------------
-describe("html to vdom", function() {
-  let elm, vnode0;
-  beforeEach(function() {
-    elm = document.createElement("div");
-    vnode0 = elm;
-  });
-
-  test("empty strings return empty list", function() {
-    expect(htmlToVDOM("")).toEqual([]);
-  });
-
-  test("just text", function() {
-    const nodeList = htmlToVDOM("simple text");
-    expect(nodeList).toHaveLength(1);
-    expect(nodeList[0]).toEqual({ text: "simple text" });
-  });
-
-  test("empty tag", function() {
-    const nodeList = htmlToVDOM("<span></span>");
-    expect(nodeList).toHaveLength(1);
-    elm = patch(vnode0, nodeList[0]).elm;
-    expect(elm.outerHTML).toEqual("<span></span>");
-  });
-
-  test("tag with text", function() {
-    const nodeList = htmlToVDOM("<span>abc</span>");
-    expect(nodeList).toHaveLength(1);
-    elm = patch(vnode0, nodeList[0]).elm;
-    expect(elm.outerHTML).toEqual("<span>abc</span>");
-  });
-
-  test("tag with attribute", function() {
-    const nodeList = htmlToVDOM(`<span a="1" b="2">abc</span>`);
-    expect(nodeList).toHaveLength(1);
-    elm = patch(vnode0, nodeList[0]).elm;
-    expect(elm.outerHTML).toEqual(`<span a="1" b="2">abc</span>`);
-  });
-
-  test("misc", function() {
-    const nodeList = htmlToVDOM(`<span a="1" b="2">abc<div>1</div></span>`);
-    expect(nodeList).toHaveLength(1);
-    elm = patch(vnode0, nodeList[0]).elm;
-    expect(elm.outerHTML).toEqual(`<span a="1" b="2">abc<div>1</div></span>`);
-  });
-});
@@ -0,0 +1,173 @@
+import {
+  buildData,
+  startMeasure,
+  stopMeasure,
+  formatNumber
+} from "../shared/utils.js";
+
+//------------------------------------------------------------------------------
+// Likes Counter Widget
+//------------------------------------------------------------------------------
+class Counter extends owl.Component {
+  state = { counter: 0 };
+  template = "Counter";
+
+  increment() {
+    this.state.counter++;
+  }
+}
+
+//------------------------------------------------------------------------------
+// Message Widget
+//------------------------------------------------------------------------------
+class Message extends owl.Component {
+  widgets = { Counter };
+  template = "Message";
+
+  shouldUpdate(nextProps) {
+    return nextProps !== this.props;
+  }
+  removeMessage() {
+    this.trigger("remove_message", {
+      id: this.props.id
+    });
+  }
+}
+
+//------------------------------------------------------------------------------
+// Root Widget
+//------------------------------------------------------------------------------
+class App extends owl.Component {
+  widgets = { Message };
+  state = { messages: [], multipleFlag: false, clearAfterFlag: false };
+  template = "App";
+
+  mounted() {
+    this.log(
+      `Benchmarking Owl v${owl._version} (build date: ${
+        owl._date
+      })`
+    );
+  }
+
+  benchmark(message, fn, callback) {
+    if (this.state.multipleFlag) {
+      const N = 20;
+      let n = N;
+      let total = 0;
+      let cb = info => {
+        let finalize = () => {
+          n--;
+          total += info.delta;
+          if (n === 0) {
+            const avg = total / N;
+            this.log(`Average: ${formatNumber(avg)}ms`, true);
+            if (callback) {
+              callback();
+            }
+          } else {
+            this._benchmark(message, fn, cb);
+          }
+        };
+
+        if (this.state.clearAfterFlag) {
+          this._benchmark(
+            "clear",
+            () => {
+              this.state.messages = [];
+            },
+            finalize,
+            false
+          );
+        } else {
+          finalize();
+        }
+      };
+      this._benchmark(message, fn, cb);
+    } else {
+      this._benchmark(message, fn, callback);
+    }
+  }
+
+  _benchmark(message, fn, cb, log = true) {
+    setTimeout(() => {
+      startMeasure(message);
+      fn();
+      stopMeasure(info => {
+        if (log) {
+          this.log(info.msg);
+        }
+        if (cb) {
+          cb(info);
+        }
+      });
+    }, 10);
+  }
+
+  addMessages(n) {
+    this.benchmark("add " + n, () => {
+      const newMessages = buildData(n);
+      this.state.messages.push.apply(this.state.messages, newMessages);
+    });
+  }
+
+  clear() {
+    this._benchmark("clear", () => {
+      this.state.messages = [];
+    });
+  }
+
+  updateSomeMessages() {
+    this.benchmark("update every 10th", () => {
+      const messages = this.state.messages;
+      for (let i = 0; i < this.state.messages.length; i += 10) {
+        const msg = Object.assign({}, messages[i]);
+        msg.author += "!!!";
+        this.set(messages, i, msg);
+      }
+    });
+  }
+
+  removeMessage(data) {
+    this.benchmark("remove message", () => {
+      const index = this.state.messages.findIndex(m => m.id === data.id);
+      this.state.messages.splice(index, 1);
+    });
+  }
+
+  log(str, isBold) {
+    const div = document.createElement("div");
+    if (isBold) {
+      div.classList.add("bold");
+    }
+    div.textContent = `> ${str}`;
+    this.refs.log.appendChild(div);
+    this.refs.log.scrollTop = this.refs.log.scrollHeight;
+  }
+
+  clearLog() {
+    this.refs.log.innerHTML = "";
+  }
+
+  toggleMultiple() {
+    this.state.multipleFlag = !this.state.multipleFlag;
+  }
+
+  toggleClear() {
+    this.state.clearAfterFlag = !this.state.clearAfterFlag;
+  }
+}
+
+//------------------------------------------------------------------------------
+// Application initialization
+//------------------------------------------------------------------------------
+async function start() {
+  const templates = await owl.utils.loadTemplates("templates.xml");
+  const env = {
+    qweb: new owl.QWeb(templates)
+  };
+  const app = new App(env);
+  app.mount(document.body);
+}
+
+start();
@@ -2,11 +2,12 @@
 <html lang="en">
 <head>
  <meta charset="UTF-8">
-  <title>OWL v0.24.0 Benchmark</title>
+  <title>OWL 0.10.0 Benchmark</title>
  <link href="../shared/main.css" rel="stylesheet"/>
  <script src='owl.js'></script>
 </head>
 <body>
+  <div id='main'></div>
  <script src='app.js' type="module"></script>
 </body>
 </html>
@@ -0,0 +1,50 @@
+<templates>
+  <div t-name="App" class="main">
+      <div class="left-thing">
+        <div class="title">Actions</div>
+        <div class="panel">
+          <button t-on-click="addMessages(100)">Add 100 messages</button>
+          <button t-on-click="addMessages(1000)">Add 1k messages</button>
+          <button t-on-click="addMessages(10000)">Add 10k messages</button>
+          <button t-on-click="addMessages(30000)">Add 30k messages</button>
+          <button t-on-click="updateSomeMessages">Update every 10th messages</button>
+          <button t-on-click="clear">Clear</button>
+        </div>
+        <div class="flags">
+            <div>
+                <input type="checkbox" id="multipleflag" t-on-change="toggleMultiple" t-att-checked="state.multipleFlag"/>
+                <label for="multipleflag">Do it 20x</label>
+            </div>
+            <div>
+                <input type="checkbox" id="clearFlag" t-on-change="toggleClear"  t-att-checked="state.clearAfterFlag"/>
+                <label for="clearFlag">Clear after</label>
+            </div>
+        </div>
+        <div class="info">Number of messages: <t t-esc="state.messages.length"/></div>
+        <hr/>
+        <div class="title">Log <span class="clear-log" t-on-click="clearLog">(clear)</span></div>
+        <div class="log">
+            <div class="log-content" t-ref="'log'"/>
+        </div>
+      </div>
+      <div class="right-thing">
+          <div class="content" t-on-remove-message="removeMessage">
+              <t t-foreach="state.messages" t-as="message">
+                  <t t-widget="Message" t-key="message.id" t-props="message" t-on-remove_message="removeMessage"/>
+              </t>
+          </div>
+      </div>
+  </div>
+
+  <div t-name="Message" class="message">
+    <span class="author"><t t-esc="props.author"/></span>
+    <span class="msg"><t t-esc="props.msg"/></span>
+    <button class="remove" t-on-click="removeMessage">Remove</button>
+    <t t-widget="Counter"/>
+  </div>
+
+  <div t-name="Counter">
+    <button t-on-click="increment">Value: <t t-esc="state.counter"/></button>
+  </div>
+
+</templates>
@@ -0,0 +1,170 @@
+import {
+  buildData,
+  startMeasure,
+  stopMeasure,
+  formatNumber
+} from "../shared/utils.js";
+
+//------------------------------------------------------------------------------
+// Likes Counter Widget
+//------------------------------------------------------------------------------
+class Counter extends owl.Component {
+  state = { counter: 0 };
+
+  increment() {
+    this.state.counter++;
+  }
+}
+
+//------------------------------------------------------------------------------
+// Message Widget
+//------------------------------------------------------------------------------
+class Message extends owl.Component {
+  widgets = { Counter };
+
+  shouldUpdate(nextProps) {
+    return nextProps !== this.props;
+  }
+  removeMessage() {
+    this.trigger("remove_message", {
+      id: this.props.id
+    });
+  }
+}
+
+//------------------------------------------------------------------------------
+// Root Widget
+//------------------------------------------------------------------------------
+class App extends owl.Component {
+  widgets = { Message };
+  state = { messages: [], multipleFlag: false, clearAfterFlag: false };
+
+  mounted() {
+    this.log(
+      `Benchmarking Owl v${owl.__info__.version} (build date: ${
+        owl.__info__.date
+      })`
+    );
+  }
+
+  benchmark(message, fn, callback) {
+    if (this.state.multipleFlag) {
+      const N = 20;
+      let n = N;
+      let total = 0;
+      let cb = info => {
+        let finalize = () => {
+          n--;
+          total += info.delta;
+          if (n === 0) {
+            const avg = total / N;
+            this.log(`Average: ${formatNumber(avg)}ms`, true);
+            if (callback) {
+              callback();
+            }
+          } else {
+            this._benchmark(message, fn, cb);
+          }
+        };
+
+        if (this.state.clearAfterFlag) {
+          this._benchmark(
+            "clear",
+            () => {
+              this.state.messages = [];
+            },
+            finalize,
+            false
+          );
+        } else {
+          finalize();
+        }
+      };
+      this._benchmark(message, fn, cb);
+    } else {
+      this._benchmark(message, fn, callback);
+    }
+  }
+
+  _benchmark(message, fn, cb, log = true) {
+    setTimeout(() => {
+      startMeasure(message);
+      fn();
+      stopMeasure(info => {
+        if (log) {
+          this.log(info.msg);
+        }
+        if (cb) {
+          cb(info);
+        }
+      });
+    }, 10);
+  }
+
+  addMessages(n) {
+    this.benchmark("add " + n, () => {
+      const newMessages = buildData(n);
+      this.state.messages.push.apply(this.state.messages, newMessages);
+    });
+  }
+
+  clear() {
+    this.benchmark("clear", () => {
+      this.state.messages = [];
+    });
+  }
+
+  updateSomeMessages() {
+    this.benchmark("update every 10th", () => {
+      const messages = this.state.messages;
+      for (let i = 0; i < this.state.messages.length; i += 10) {
+        const msg = Object.assign({}, messages[i]);
+        msg.author += "!!!";
+        this.set(messages, i, msg);
+      }
+    });
+  }
+
+  removeMessage(data) {
+    this.benchmark("remove message", () => {
+      const index = this.state.messages.findIndex(m => m.id === data.id);
+      this.state.messages.splice(index, 1);
+    });
+  }
+
+  log(str, isBold) {
+    const div = document.createElement("div");
+    if (isBold) {
+      div.classList.add("bold");
+    }
+    div.textContent = `> ${str}`;
+    this.refs.log.appendChild(div);
+    this.refs.log.scrollTop = this.refs.log.scrollHeight;
+  }
+
+  clearLog() {
+    this.refs.log.innerHTML = "";
+  }
+
+  toggleMultiple() {
+    this.state.multipleFlag = !this.state.multipleFlag;
+  }
+
+  toggleClear() {
+    this.state.clearAfterFlag = !this.state.clearAfterFlag;
+  }
+}
+
+//------------------------------------------------------------------------------
+// Application initialization
+//------------------------------------------------------------------------------
+async function start() {
+  const templates = await owl.utils.loadTemplates("templates.xml");
+  const env = {
+    qweb: new owl.QWeb(templates)
+  };
+  const app = new App(env);
+  app.mount(document.body);
+}
+
+start();
--- a/Show More
+++ b/Show More