[REL] v1.0.0-beta2

closes #554

README.md

@@ -1,10 +1,10 @@
 <h1 align="center">🦉 <a href="https://odoo.github.io/owl/">Odoo Web Library</a> 🦉</h1>
 
-_A no nonsense web framework for structured, dynamic and maintainable applications_
+_Class based components with hooks, reactive state and concurrent mode_
 
 ## Project Overview
 
-The Odoo Web Library (OWL) is a smallish (~18kb gzipped) UI framework intended to
+The Odoo Web Library (OWL) is a smallish (~<20kb 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:
@@ -104,8 +104,8 @@ Submit a PR!
 
 If you want to use a simple `<script>` tag, the last release can be downloaded here:
 
-- [owl-1.0.0-alpha3.js](https://github.com/odoo/owl/releases/download/v1.0.0-alpha3/owl.js)
-- [owl-1.0.0-alpha3.min.js](https://github.com/odoo/owl/releases/download/v1.0.0-alpha3/owl.min.js)
+- [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)
 
 Some npm scripts are available:
 

doc/learning/testing_components.md

@@ -0,0 +1,132 @@
+# 🦉 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();
+      }
+    }
+  });
+}
+```

doc/learning/tutorial_todoapp.md

@@ -297,7 +297,7 @@ A lot of stuff happened here:
 - the `Task` component has a `props` key: this is only useful for validation
   purpose. It says that each `Task` should be given exactly one prop, named
   `task`. If this is not the case, Owl will throw an
-  [error](../reference/component.md#props-validation). This is extremely
+  [error](../reference/props_validation.md). This is extremely
   useful when refactoring components
 - finally, to activate the props validation, we need to set Owl's
   [mode](../reference/config.md#mode) to `dev`. This is done in the `setup`

doc/readme.md

@@ -4,6 +4,7 @@
 
 - [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)
@@ -12,6 +13,7 @@
 - [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)
@@ -23,6 +25,7 @@
 
 - [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)
 
 ## Miscellaneous
 
@@ -47,20 +50,20 @@ and `EventBus` is exported as `owl.core.EventBus`):
 ```
 Component                               misc
 Context                                     AsyncRoot
-QWeb                                    router
-Store                                       Link
-useState                                    RouteComponent
-config                                      Router
-    mode                                tags
-core                                        xml
-    EventBus                            utils
-    Observer                                debounce
-hooks                                       escape
-    onWillStart                             loadJS
-    onMounted                               loadFile
-    onWillUpdateProps                       shallowEqual
-    onWillPatch                             whenReady
-    onPatched
+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

doc/reference/component.md

@@ -14,12 +14,9 @@
   - [Composition](#composition)
   - [Event Handling](#event-handling)
   - [Form Input Bindings](#form-input-bindings)
-  - [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)
@@ -204,7 +201,7 @@ 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) for more information.
+  created/updated. See [Props Validation](props_validation.md) for more information.
 
   ```js
   class Counter extends owl.Component {
@@ -237,35 +234,60 @@ component.
 
 We explain here all the public methods of the `Component` class.
 
-- **`mount(target)`** (async): this is the main way a
+- **`mount(target, options)`** (async): this is the main way a
   component is added to the DOM: the root component is mounted to a target
-  HTMLElement. Obviously, this is asynchronous, since each children need to be
+  HTMLElement (or document fragment). 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`.
+
+  - `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.
 
-- **`unmount()`**: in case a component needs to be detached/removed from the DOM, this
+  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
   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,
+* **`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
@@ -567,11 +589,13 @@ A _business_ DOM event is triggered by a call to `trigger` on a component.
  }
 ```
 
-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.
+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.
 
 ```js
  class ParentComponent {
@@ -729,188 +753,6 @@ update a number whenever the change is done.
 
 Note: the online playground has an example to show how it works.
 
-### 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 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:
-  - `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
@@ -1023,6 +865,19 @@ be considered the `default` slot. For example:
 </div>
 ```
 
+Slots can define a default content, in case the parent did not define them:
+
+```xml
+<div t-name="Parent">
+  <Child/>
+</div>
+
+<span t-name="Child">
+  <t t-slot="default">default content</t>
+</span>
+<!-- will be rendered as: <div><span>default content</span></div> -->
+```
+
 ### Dynamic sub components
 
 It is not common, but sometimes we need a dynamic component name. In this case,
@@ -1066,48 +921,7 @@ class App extends Component<any, any, any> {
 In this example, the component `App` selects dynamically the concrete sub
 component class.
 
-### 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>
-   ```
+Note that the `t-component` directive can only be used on `<t>` nodes.
 
 ### Error Handling
 

doc/reference/concurrency_model.md

@@ -0,0 +1,183 @@
+# 🦉 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>
+   ```

doc/reference/environment.md

@@ -4,6 +4,7 @@
 
 - [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
@@ -65,6 +66,27 @@ by simply doing this:
 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:

doc/reference/hooks.md

@@ -152,9 +152,15 @@ class SomeComponent extends Component {
 }
 ```
 
-In a hook, 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.
+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`
 

doc/reference/misc.md

@@ -1,5 +1,116 @@
 # 🦉 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

doc/reference/props_validation.md

@@ -0,0 +1,103 @@
+# 🦉 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)
+    },
+  };
+```

doc/reference/qweb_templating_language.md

@@ -500,6 +500,15 @@ 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

doc/reference/store.md

@@ -25,8 +25,8 @@ 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, and will be updated if
-necessary.
+`actions`. Owl components can then connect to the store to read their relevant
+state, and they will be rerendered if the state is updated.
 
 Note: Owl store is inspired by React Redux and VueX.
 
@@ -252,19 +252,30 @@ The `useStore` hook is used to select some part of the store state. It accepts
 two arguments:
 
 - a selector function, which takes the store state as first argument (and the
-  component props as second argument) and returns
-  an object or an array (which will be then observed),
-- optionally, an object with a `store` key (if we want to override the default
-  store) and an equality function (if we want to specialize the comparison).
+  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).
 
-If the `useStore` callback selects a sub part of the store state, the component
+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 and will update the component every time this
-check fails.
+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.
 
-Also, it may not be obvious, but it is crucial to remember that the selector
-function should return an object or an array. The reason is that it needs to be
-observed, otherwise the component would not be able to react to changes.
+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`
 

doc/tooling.md

@@ -6,6 +6,7 @@
 - [Playground](#playground)
 - [Benchmarks](#benchmarks)
 - [Single File Component](#single-file-component)
+- [Debugging Script](#debugging-script)
 
 ## Overview
 
@@ -78,3 +79,28 @@ 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.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "owl-framework",
-  "version": "1.0.0-alpha3",
+  "version": "1.0.0-beta2",
   "description": "Odoo Web Library (OWL)",
   "main": "src/index.ts",
   "engines": {
@@ -39,12 +39,13 @@
     "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": "^3.6.4",
+    "typescript": "^3.7.2",
     "uglify-es": "^3.3.9"
   },
   "jest": {

roadmap.md

@@ -1,25 +1,17 @@
 # 🦉 OWL Roadmap 🦉
 
-- Current version: 1.0.0-alpha3
+- Current version: 1.0.0-beta2
 - Status: mostly stable
 
 This roadmap is only an attempt at predicting Owl's future.  Everything may
 change!
 
 
-### November 2019
-
-Owl will be used in various Odoo projects. We plan to:
-
-- fix any issues encountered
-- maybe cleanup slightly the router API
-- improve the documentation
-- improve error handling, add more helpful error messages
 
 ### December 2019
 
-If all goes well, Owl will be upgraded to beta status. From then, no API change,
-even small, is expected.
+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
 
@@ -41,7 +33,8 @@ Release v1.0
 
 Maybe:
 
-- reimplement vdom to use *block* system, like Vue 3,
+- 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.
 

src/component/component.ts

@@ -1,6 +1,7 @@
 import { Observer } from "../core/observer";
+import { OwlEvent } from "../core/owl_event";
 import { CompiledTemplate, QWeb } from "../qweb/index";
-import { h, patch, VNode } from "../vdom/index";
+import { patch, VNode } from "../vdom/index";
 import "./directive";
 import { Fiber } from "./fiber";
 import "./props_validation";
@@ -35,6 +36,10 @@ export interface Env {
   [key: string]: any;
 }
 
+interface MountOptions {
+  position?: "first-child" | "last-child" | "self";
+}
+
 /**
  * This is mostly an internal detail of implementation. The Meta interface is
  * useful to typecheck and describe the internal keys used by Owl to manage the
@@ -60,6 +65,14 @@ interface Internal<T extends Env, Props> {
   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;
 
   boundHandlers: { [key: number]: any };
   observer: Observer | null;
@@ -74,6 +87,8 @@ interface Internal<T extends Env, Props> {
   refs: { [key: string]: Component<T, any> | HTMLElement | undefined } | null;
 }
 
+export const portalSymbol = Symbol("portal"); // FIXME
+
 //------------------------------------------------------------------------------
 // Component
 //------------------------------------------------------------------------------
@@ -90,6 +105,7 @@ export class Component<T extends Env, Props extends {}> {
   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:
@@ -169,6 +185,7 @@ export class Component<T extends Env, Props extends {}> {
       children: {},
       cmap: {},
       currentFiber: null,
+      parentLastFiberId: 0,
       boundHandlers: {},
       mountedCB: null,
       willUnmountCB: null,
@@ -179,7 +196,8 @@ export class Component<T extends Env, Props extends {}> {
       observer: null,
       renderFn: qweb.render.bind(qweb, template),
       classObj: null,
-      refs: null
+      refs: null,
+      scope: null
     };
   }
 
@@ -276,38 +294,34 @@ export class Component<T extends Env, Props extends {}> {
    *
    * Note that a component can be mounted an unmounted several times
    */
-  async mount(target: HTMLElement): Promise<void> {
+  async mount(target: HTMLElement | DocumentFragment, options: MountOptions = {}): Promise<void> {
+    const position = options.position || "last-child";
     const __owl__ = this.__owl__;
     if (__owl__.isMounted) {
       return Promise.resolve();
     }
-    if (!(target instanceof HTMLElement)) {
+    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);
     }
-    return new Promise((resolve, reject) => {
-      const fiber = new Fiber(null, this, undefined, undefined, false);
-      scheduler.addFiber(fiber, err => {
-        if (err) {
-          reject(err);
-          return;
-        }
-        if (!__owl__.isDestroyed) {
-          this.__patch(fiber.vnode);
-          target.appendChild(this.el!);
-          if (document.body.contains(target)) {
-            this.__callMounted();
-          }
-        }
-        resolve();
-      });
-      if (!__owl__.vnode) {
-        this.__prepareAndRender(fiber);
-      } else {
-        this.__render(fiber);
-      }
-    });
+    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;
+    if (!__owl__.vnode) {
+      this.__prepareAndRender(fiber, () => {});
+    } else {
+      this.__render(fiber);
+    }
+    return scheduler.addFiber(fiber);
   }
 
   /**
@@ -332,26 +346,34 @@ export class Component<T extends Env, Props extends {}> {
    */
   async render(force: boolean = false): Promise<void> {
     const __owl__ = this.__owl__;
-    if (
-      (!__owl__.isMounted && !__owl__.currentFiber) ||
-      (__owl__.currentFiber && !__owl__.currentFiber.isRendered)
-    ) {
+    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.
       return;
     }
-    return new Promise((resolve, reject) => {
-      const fiber = new Fiber(null, this, undefined, undefined, force);
-      scheduler.addFiber(fiber.root, err => {
-        if (err) {
-          reject(err);
-          return;
-        }
-        if (__owl__.isMounted && fiber === fiber.root) {
-          fiber.patchComponents();
-        }
-        resolve();
-      });
-      this.__render(fiber);
+    if (__owl__.currentFiber && !__owl__.currentFiber.isRendered) {
+      return scheduler.addFiber(__owl__.currentFiber.root);
+    }
+    // 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);
   }
 
   /**
@@ -390,14 +412,7 @@ export class Component<T extends Env, Props extends {}> {
    * willUnmount().
    */
   trigger(eventType: string, payload?: any) {
-    if (this.el) {
-      const ev = new CustomEvent(eventType, {
-        bubbles: true,
-        cancelable: true,
-        detail: payload
-      });
-      this.el.dispatchEvent(ev);
-    }
+    this.__trigger(this, eventType, payload);
   }
 
   //--------------------------------------------------------------------------
@@ -437,27 +452,18 @@ export class Component<T extends Env, Props extends {}> {
     __owl__.isDestroyed = true;
     delete __owl__.vnode;
     if (__owl__.currentFiber) {
-      __owl__.currentFiber.isCancelled = true;
+      __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;
-    try {
-      this.mounted();
-      if (__owl__.mountedCB) {
-        __owl__.mountedCB();
-      }
-    } catch (e) {
-      console.error(e); // TODO : add a test
+    __owl__.currentFiber = null;
+    this.mounted();
+    if (__owl__.mountedCB) {
+      __owl__.mountedCB();
     }
   }
 
@@ -468,6 +474,10 @@ 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];
@@ -476,27 +486,40 @@ 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,
-    vars: any,
-    previousSibling?: Fiber | null
-  ): Promise<void> {
+  async __updateProps(nextProps: Props, parentFiber: Fiber, scope: any): Promise<void> {
+    this.__owl__.scope = scope;
     const shouldUpdate = parentFiber.force || this.shouldUpdate(nextProps);
     if (shouldUpdate) {
       const __owl__ = this.__owl__;
-      const fiber = new Fiber(parentFiber, this, scope, vars, parentFiber.force);
+      const fiber = new Fiber(parentFiber, this, parentFiber.force, null);
       if (!parentFiber.child) {
         parentFiber.child = fiber;
       } else {
-        previousSibling!.sibling = fiber;
+        parentFiber.lastChild!.sibling = fiber;
       }
+      parentFiber.lastChild = fiber;
 
       const defaultProps = (<any>this.constructor).defaultProps;
       if (defaultProps) {
@@ -509,7 +532,7 @@ export class Component<T extends Env, Props extends {}> {
         this.willUpdateProps(nextProps),
         __owl__.willUpdatePropsCB && __owl__.willUpdatePropsCB(nextProps)
       ]);
-      if (fiber.isCancelled) {
+      if (fiber.isCompleted) {
         return;
       }
       this.props = nextProps;
@@ -522,27 +545,39 @@ 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) {
+  __patch(vnode: VNode) {
     const __owl__ = this.__owl__;
-    const target = __owl__.vnode || document.createElement(vnode.sel!);
-    __owl__.vnode = patch(target, vnode);
-    __owl__.currentFiber = null;
+    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);
+    }
   }
 
   /**
    * The __prepare method is only called by the t-component directive, when a
-   * subcomponent is created. It gets its scope and vars, if any, from the
+   * subcomponent is created. It gets its scope, if any, from the
    * parent template.
    */
-  __prepare(parentFiber: Fiber, scope: any, vars: any, previousSibling?: Fiber | null) {
-    const fiber = new Fiber(parentFiber, this, scope, vars, parentFiber.force);
+  __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 {
-      previousSibling!.sibling = fiber;
+      parentFiber.lastChild!.sibling = fiber;
     }
-    return this.__prepareAndRender(fiber);
+    parentFiber.lastChild = fiber;
+    this.__prepareAndRender(fiber, cb);
+    return fiber;
   }
 
   __getTemplate(qweb: QWeb): string {
@@ -564,19 +599,19 @@ export class Component<T extends Env, Props extends {}> {
     }
     return p._template;
   }
-  async __prepareAndRender(fiber: Fiber) {
+  async __prepareAndRender(fiber: Fiber, cb: CallableFunction) {
     try {
       await Promise.all([this.willStart(), this.__owl__.willStartCB && this.__owl__.willStartCB()]);
     } catch (e) {
       fiber.handleError(e);
-      fiber.vnode = h("div"); // -> we render this div at the end
       return Promise.resolve();
     }
     if (this.__owl__.isDestroyed) {
       return Promise.resolve();
     }
-    if (!fiber.isCancelled) {
+    if (!fiber.isCompleted) {
       this.__render(fiber);
+      cb();
     }
   }
 
@@ -585,49 +620,45 @@ export class Component<T extends Env, Props extends {}> {
     if (__owl__.observer) {
       __owl__.observer.allowMutations = false;
     }
-    let vnode;
+    let error;
     try {
-      vnode = __owl__.renderFn!(this, {
+      let vnode = __owl__.renderFn!(this, {
         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) {
-      vnode = __owl__.vnode || h("div");
-      fiber.handleError(e);
+      error = e;
     }
-    fiber.vnode = vnode;
     if (__owl__.observer) {
       __owl__.observer.allowMutations = true;
     }
 
-    // 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) {
-      vnode.data.class = Object.assign(vnode.data.class || {}, __owl__.classObj);
-    }
     fiber.root.counter--;
     fiber.isRendered = true;
-  }
-
-  /**
-   * Only called by qweb t-component directive
-   */
-  __mount(fiber: Fiber, elm: HTMLElement): VNode {
-    if (fiber !== this.__owl__.currentFiber) {
-      fiber = this.__owl__.currentFiber!; // TODO: check if we can remove fiber arg
+    if (error) {
+      fiber.handleError(error);
     }
-    const vnode = fiber.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);
-    __owl__.currentFiber = null;
-    if (__owl__.parent!.__owl__.isMounted && !__owl__.isMounted) {
-      this.__callMounted();
-    }
-    return __owl__.vnode;
   }
 
   /**

src/component/directive.ts

@@ -190,10 +190,10 @@ QWeb.addDirective({
   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 hasDynamicProps = node.getAttribute("t-props") ? true : false;
 
     // t-on- events and t-transition
@@ -226,22 +226,9 @@ QWeb.addDirective({
     let propStr = Object.keys(props)
       .map(k => k + ":" + props[k])
       .join(",");
-    let defID = ctx.generateID();
     let componentID = ctx.generateID();
 
-    let locationExpr = `\`__${ctx.generateID()}__`;
-    for (let i = 0; i < ctx.loopNumber - 1; i++) {
-      locationExpr += `\${i${i + 1}}__`;
-    }
-    if (ctx.lastNodeKey || ctx.currentKey) {
-      const k = ctx.lastNodeKey || ctx.currentKey;
-      ctx.addLine(`let templateId${componentID} = ${locationExpr}\` + ${k};`);
-    } else {
-      locationExpr += ctx.loopNumber ? `\${i${ctx.loopNumber}}__\`` : "`";
-      ctx.addLine(`let templateId${componentID} = ${locationExpr};`);
-    }
-    const templateId = `templateId${componentID}`;
-
+    const templateKey = ctx.generateTemplateKey();
     let ref = node.getAttribute("t-ref");
     let refExpr = "";
     let refKey: string = "";
@@ -251,10 +238,6 @@ QWeb.addDirective({
       ctx.addLine(`const ${refKey} = ${ctx.interpolate(ref)};`);
       refExpr = `context.__owl__.refs[${refKey}] = w${componentID};`;
     }
-    let transitionsInsertCode = "";
-    if (transition) {
-      transitionsInsertCode = `utils.transitionInsert(vn, '${transition}');`;
-    }
     let finalizeComponentCode = `w${componentID}.destroy();`;
     if (ref) {
       finalizeComponentCode += `delete context.__owl__.refs[${refKey}];`;
@@ -263,6 +246,7 @@ QWeb.addDirective({
       finalizeComponentCode = `let finalize = () => {
           ${finalizeComponentCode}
         };
+        delete w${componentID}.__owl__.transitionInserted;
         utils.transitionRemove(vn, '${transition}', finalize);`;
     }
 
@@ -301,7 +285,7 @@ QWeb.addDirective({
       }
       let eventsCode = events
         .map(function([eventName, mods, handlerValue, extraArgs]) {
-          let params = "owner";
+          let params = "context";
           if (extraArgs) {
             if (ctx.loopNumber) {
               let argId = ctx.generateID();
@@ -309,20 +293,20 @@ QWeb.addDirective({
               // be set asynchronously later when the widget is ready, and the
               // context might be different.
               ctx.addLine(`let arg${argId} = ${ctx.formatExpression(extraArgs)};`);
-              params = `owner, arg${argId}`;
+              params = `context, arg${argId}`;
             } else {
-              params = `owner, ${ctx.formatExpression(extraArgs)}`;
+              params = `context, ${ctx.formatExpression(extraArgs)}`;
             }
           }
-          let handler = `function (e) {`;
+          let handler = `function (e) {if(!context.__owl__.isMounted){return}`;
           handler += mods
             .map(function(mod) {
               return T_COMPONENT_MODS_CODE[mod];
             })
             .join("");
           if (handlerValue) {
-            handler += `const fn = owner['${handlerValue}'];`;
-            handler += `if (fn) { fn.call(${params}, e); } else { owner.${handlerValue}; }`;
+            handler += `const fn = context['${handlerValue}'];`;
+            handler += `if (fn) { fn.call(${params}, e); } else { context.${handlerValue}; }`;
           }
           handler += `}`;
           return `vn.elm.addEventListener('${eventName}', ${handler});`;
@@ -334,7 +318,7 @@ QWeb.addDirective({
     }
 
     ctx.addLine(
-      `let w${componentID} = ${templateId} in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[${templateId}]] : false;`
+      `let w${componentID} = ${templateKey} in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[${templateKey}]] : false;`
     );
     let shouldProxy = !ctx.parentNode;
     if (shouldProxy) {
@@ -364,25 +348,9 @@ QWeb.addDirective({
     }
 
     // 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"]);
-        }
-      }
-    }
 
-    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";
-    }
+    let scope = hasSlots ? `Object.assign(Object.create(context), scope)` : "undefined";
 
     ctx.addIf(`w${componentID}`);
 
@@ -392,8 +360,7 @@ QWeb.addDirective({
       styleCode = `.then(()=>{if (w${componentID}.__owl__.isDestroyed) {return};w${componentID}.el.style=${tattStyle};});`;
     }
     ctx.addLine(
-      `w${componentID}.__updateProps(props${componentID}, extra.fiber${scopeVars &&
-        ", " + scopeVars}, sibling)${styleCode};`
+      `w${componentID}.__updateProps(props${componentID}, extra.fiber, ${scope})${styleCode};`
     );
     ctx.addLine(`let pvnode = w${componentID}.__owl__.pvnode;`);
     if (registerCode) {
@@ -421,7 +388,13 @@ QWeb.addDirective({
       `if (!W${componentID}) {throw new Error('Cannot find the definition of component "' + componentKey${componentID} + '"')}`
     );
     ctx.addLine(`w${componentID} = new W${componentID}(parent, props${componentID});`);
-    ctx.addLine(`parent.__owl__.cmap[${templateId}] = w${componentID}.__owl__.id;`);
+    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, '${transition}');}};`
+      );
+    }
+    ctx.addLine(`parent.__owl__.cmap[${templateKey}] = w${componentID}.__owl__.id;`);
 
     if (hasSlots) {
       const clone = <Element>node.cloneNode(true);
@@ -448,14 +421,13 @@ QWeb.addDirective({
       }
     }
 
-    ctx.addLine(`let def${defID} = w${componentID}.__prepare(extra.fiber, ${scopeVars}, sibling);`);
-    // hack: specify empty remove hook to prevent the node from being removed from the DOM
     ctx.addLine(
-      `let pvnode = h('dummy', {key: ${templateId}, hook: {insert(vn) { let nvn=w${componentID}.__mount(fiber, pvnode.elm);pvnode.elm=nvn.elm;${refExpr}${transitionsInsertCode}},remove() {},destroy(vn) {${finalizeComponentCode}}}});`
+      `let fiber = w${componentID}.__prepare(extra.fiber, ${scope}, () => { const vnode = fiber.vnode; pvnode.sel = vnode.sel; ${createHook}});`
     );
-    ctx.addLine(`const fiber = w${componentID}.__owl__.currentFiber;`);
+    // hack: specify empty remove hook to prevent the node from being removed from the DOM
+    const insertHook = refExpr ? `insert(vn) {${refExpr}},` : "";
     ctx.addLine(
-      `def${defID}.then(function () {if (fiber.isCancelled) {return;} const vnode = fiber.vnode; pvnode.sel = vnode.sel; ${createHook}});`
+      `let pvnode = h('dummy', {key: ${templateKey}, hook: {${insertHook}remove() {},destroy(vn) {${finalizeComponentCode}}}});`
     );
     if (registerCode) {
       ctx.addLine(registerCode);
@@ -471,7 +443,7 @@ QWeb.addDirective({
       ctx.addLine(`w${componentID}.__owl__.classObj=${classObj};`);
     }
 
-    ctx.addLine(`sibling = w${componentID}.__owl__.currentFiber || sibling;`);
+    ctx.addLine(`w${componentID}.__owl__.parentLastFiberId = extra.fiber.id;`);
 
     return true;
   }

src/component/fiber.ts

@@ -1,4 +1,4 @@
-import { VNode } from "../vdom/index";
+import { h, VNode } from "../vdom/index";
 import { Component } from "./component";
 import { scheduler } from "./scheduler";
 
@@ -16,13 +16,17 @@ import { scheduler } from "./scheduler";
  */
 
 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;
 
-  // isCancelled means that the rendering corresponding to this fiber and its
-  // children is cancelled. No extra work should be done.
-  isCancelled: boolean = false;
+  // 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,
@@ -42,8 +46,9 @@ export class Fiber {
   // scheduler.
   counter: number = 0;
 
+  inserter: (el: HTMLElement) => void | null;
+
   scope: any;
-  vars: any;
 
   component: Component<any, any>;
   vnode: VNode | null = null;
@@ -51,27 +56,58 @@ export class Fiber {
   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>, scope, vars, force) {
-    this.force = force;
-    this.scope = scope;
-    this.vars = vars;
+  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 = component.__owl__.currentFiber;
-    if (oldFiber && !oldFiber.isCancelled) {
-      this._remapFiber(oldFiber);
+    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++;
 
-    component.__owl__.currentFiber = this;
+    __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++;
   }
 
   /**
@@ -82,14 +118,18 @@ export class Fiber {
    */
   _remapFiber(oldFiber: Fiber) {
     oldFiber.cancel();
+    this.shouldPatch = oldFiber.shouldPatch;
     if (oldFiber === oldFiber.root) {
-      oldFiber.root.counter++;
+      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 {
@@ -132,48 +172,69 @@ export class Fiber {
   }
 
   /**
-   * 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
+   * 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.
    */
-  patchComponents() {
+  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) {
-      if (f.shouldPatch) {
-        patchQueue.push(f);
-      }
+      patchQueue.push(f);
       return f.child;
     };
     this._walk(doWork);
-    let component: Component<any, any> = this.component;
     const patchLen = patchQueue.length;
-    try {
-      for (let i = 0; i < patchLen; i++) {
-        component = patchQueue[i].component;
+
+    // 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();
       }
-    } catch (e) {
-      console.error(e);
     }
-    for (let i = 0; i < patchLen; i++) {
+
+    // 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);
+      component.__patch(fiber.vnode!);
+      if (!fiber.shouldPatch && (!fiber.inserter || i !== 0)) {
+        component.__owl__.pvnode!.elm = component.__owl__.vnode!.elm;
+      }
+      component.__owl__.currentFiber = null;
     }
-    try {
-      for (let i = patchLen - 1; i >= 0; i--) {
-        component = patchQueue[i].component;
+
+    // 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();
       }
-    } catch (e) {
-      console.error(e);
     }
   }
 
@@ -185,7 +246,7 @@ export class Fiber {
       if (!f.isRendered) {
         f.root.counter--;
       }
-      f.isCancelled = true;
+      f.isCompleted = true;
       return f.child;
     });
   }
@@ -199,10 +260,12 @@ export class Fiber {
    * being in a corrupted state.
    */
   handleError(error: Error) {
-    let canCatch = false;
     let component = this.component;
-    let qweb = component.env.qweb;
+    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!;
@@ -210,10 +273,7 @@ export class Fiber {
     qweb.trigger("error", error);
 
     if (canCatch) {
-      setTimeout(() => {
-        console.error(error);
-        component.catchError!(error);
-      });
+      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

src/component/props_validation.ts

@@ -48,7 +48,7 @@ QWeb.utils.validateProps = function(Widget, props: Object) {
         throw e;
       }
       if (!isValid) {
-        throw new Error(`Props '${propName}' of invalid type in component '${Widget.name}'`);
+        throw new Error(`Invalid Prop '${propName}' in component '${Widget.name}'`);
       }
     }
     for (let propName in props) {
@@ -89,13 +89,16 @@ function isValidProp(prop, propDef): boolean {
   if (propDef.optional && prop === undefined) {
     return true;
   }
-  let result = isValidProp(prop, propDef.type);
-  if (propDef.type === Array) {
+  let result = propDef.type ? isValidProp(prop, propDef.type) : true;
+  if (propDef.validate) {
+    result = result && propDef.validate(prop);
+  }
+  if (propDef.type === Array && propDef.element) {
     for (let i = 0, iLen = prop.length; i < iLen; i++) {
       result = result && isValidProp(prop[i], propDef.element);
     }
   }
-  if (propDef.type === Object) {
+  if (propDef.type === Object && propDef.shape) {
     const shape = propDef.shape;
     for (let key in shape) {
       result = result && isValidProp(prop[key], shape[key]);

src/component/scheduler.ts

@@ -25,14 +25,38 @@ export class Scheduler {
     this.requestAnimationFrame = requestAnimationFrame;
   }
 
-  addFiber(fiber, callback) {
-    this.tasks.push({ fiber, callback });
-    if (this.isRunning) {
-      return;
-    }
+  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.
@@ -41,26 +65,34 @@ export class Scheduler {
     let tasks = this.tasks;
     this.tasks = [];
     tasks = tasks.filter(task => {
-      if (task.fiber.isCancelled) {
+      if (task.fiber.isCompleted) {
+        task.callback();
         return false;
       }
       if (task.fiber.counter === 0) {
-        task.callback(task.fiber.error);
+        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.isRunning = true;
     this.requestAnimationFrame(() => {
       this.flush();
-      if (this.tasks.length > 0) {
+      if (this.isRunning) {
         this.scheduleTasks();
-      } else {
-        this.isRunning = false;
       }
     });
   }

src/context.ts

@@ -2,7 +2,7 @@ import { Component } from "./component/component";
 import { scheduler } from "./component/scheduler";
 import { EventBus } from "./core/event_bus";
 import { Observer } from "./core/observer";
-import { onWillUnmount } from "./hooks";
+
 /**
  * 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,
@@ -45,7 +45,16 @@ export class Context extends EventBus {
   constructor(state: Object = {}) {
     super();
     this.observer = new Observer();
-    this.observer.notifyCB = this.__notifyComponents.bind(this);
+    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 = [];
   }
@@ -72,13 +81,7 @@ export class Context extends EventBus {
     const subscriptions = this.subscriptions.update;
     const groups = partitionBy(subscriptions, s => (s.owner ? s.owner.__owl__.depth : -1));
     for (let group of groups) {
-      const proms = Promise.all(
-        group.map(sub => {
-          if (sub.owner ? sub.owner.__owl__.isMounted : true) {
-            return sub.callback.call(sub.owner, rev);
-          }
-        })
-      );
+      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
@@ -87,7 +90,7 @@ export class Context extends EventBus {
       // promise to resolve earlier, which means that there is a chance of
       // processing the next group in the same frame.
       scheduler.flush();
-      await proms;
+      await Promise.all(proms);
     }
   }
 }
@@ -135,9 +138,11 @@ export function useContextWithCB(ctx: Context, component: Component<any, any>, m
       await method();
     }
   });
-  onWillUnmount(() => {
+  const __destroy = component.__destroy;
+  component.__destroy = parent => {
     ctx.off("update", component);
     delete mapping[id];
-  });
+    __destroy.call(component, parent);
+  };
   return ctx.state;
 }

src/core/observer.ts

@@ -20,18 +20,9 @@
 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) {
@@ -65,7 +56,7 @@ export class Observer {
           }
           self._updateRevNumber(target);
           target[key] = newVal;
-          self.notifyChange();
+          self.notifyCB();
         }
         return true;
       },
@@ -73,7 +64,7 @@ export class Observer {
         if (key in target) {
           delete target[key];
           self._updateRevNumber(target);
-          self.notifyChange();
+          self.notifyCB();
         }
         return true;
       }

src/core/owl_event.ts

@@ -0,0 +1,15 @@
+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;
+  }
+}

src/index.ts

@@ -12,6 +12,7 @@ import * as _store from "./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";
@@ -29,7 +30,7 @@ export const router = { Router, RouteComponent, Link };
 export const Store = _store.Store;
 export const utils = _utils;
 export const tags = _tags;
-export const misc = { AsyncRoot };
+export const misc = { AsyncRoot, Portal };
 export const hooks = Object.assign({}, _hooks, {
   useContext: _context.useContext,
   useDispatch: _store.useDispatch,

src/misc/portal.ts

@@ -0,0 +1,167 @@
+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;
+  }
+}

src/qweb/base_directives.ts

@@ -1,5 +1,4 @@
 import { CompilationContext } from "./compilation_context";
-import { QWebExprVar } from "./expression_parser";
 import { QWeb } from "./qweb";
 import { htmlToVDOM } from "../vdom/html_to_vdom";
 
@@ -20,35 +19,40 @@ import { htmlToVDOM } from "../vdom/html_to_vdom";
 //------------------------------------------------------------------------------
 // t-esc and t-raw
 //------------------------------------------------------------------------------
-QWeb.utils.getFragment = function(str: string): DocumentFragment {
-  const temp = document.createElement("template");
-  temp.innerHTML = str;
-  return temp.content;
-};
-
 QWeb.utils.htmlToVDOM = htmlToVDOM;
 
 function compileValueNode(value: any, node: Element, qweb: QWeb, ctx: CompilationContext) {
-  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);
+  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});`);
     }
     return;
   }
+
   let exprID: string;
   if (typeof value === "string") {
     exprID = `_${ctx.generateID()}`;
     ctx.addLine(`var ${exprID} = ${ctx.formatExpression(value)};`);
   } else {
-    exprID = value.id;
+    exprID = `scope.${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 += ${exprID};`);
     } else if (ctx.parentNode) {
@@ -62,9 +66,19 @@ function compileValueNode(value: any, node: Element, qweb: QWeb, ctx: Compilatio
         ctx.addLine(`result = vn${nodeID}`);
       }
     }
+    if (value.hasBody) {
+      ctx.stopProtectScope(protectID);
+    }
   } else {
     ctx.rootContext.shouldDefineUtils = true;
-    ctx.addLine(`c${ctx.parentNode}.push(...utils.htmlToVDOM(${exprID}));`);
+    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(${exprID}));`);
+    }
   }
   if (node.childNodes.length) {
     ctx.addElse();
@@ -101,25 +115,46 @@ QWeb.addDirective({
   name: "set",
   extraNames: ["value"],
   priority: 60,
-  atNodeEncounter({ node, ctx }): boolean {
+  atNodeEncounter({ node, qweb, ctx }): boolean {
+    ctx.rootContext.shouldDefineScope = true;
     const variable = node.getAttribute("t-set")!;
     let value = node.getAttribute("t-value")!;
+    ctx.variables[variable] = ctx.variables[variable] || {};
+    let qwebvar = ctx.variables[variable];
+    const hasBody = node.hasChildNodes();
+
+    qwebvar.id = variable;
+    qwebvar.expr = `scope.${variable}`;
     if (value) {
       const formattedValue = ctx.formatExpression(value);
-      if (ctx.variables.hasOwnProperty(variable)) {
-        ctx.addLine(`${(<QWebExprVar>ctx.variables[variable]).id} = ${formattedValue}`);
-      } else {
-        const varName = `_${ctx.generateID()}`;
-        ctx.addLine(`var ${varName} = ${formattedValue};`);
-        ctx.variables[variable] = {
-          id: varName,
-          expr: formattedValue
-        };
+      ctx.addLine(`${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();
       }
-    } else {
-      ctx.variables[variable] = {
-        xml: node.childNodes
-      };
     }
     return true;
   }
@@ -133,7 +168,7 @@ QWeb.addDirective({
   priority: 20,
   atNodeEncounter({ node, ctx }): boolean {
     let cond = ctx.getValue(node.getAttribute("t-if")!);
-    ctx.addIf(typeof cond === "string" ? ctx.formatExpression(cond) : cond.id);
+    ctx.addIf(typeof cond === "string" ? ctx.formatExpression(cond) : `scope.${cond.id!}`);
     return false;
   },
   finalize({ ctx }) {
@@ -146,7 +181,9 @@ QWeb.addDirective({
   priority: 30,
   atNodeEncounter({ node, ctx }): boolean {
     let cond = ctx.getValue(node.getAttribute("t-elif")!);
-    ctx.addLine(`else if (${typeof cond === "string" ? ctx.formatExpression(cond) : cond.id}) {`);
+    ctx.addLine(
+      `else if (${typeof cond === "string" ? ctx.formatExpression(cond) : `scope.${cond.id}`}) {`
+    );
     ctx.indent();
     return false;
   },
@@ -175,6 +212,9 @@ 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')");
     }
@@ -183,79 +223,63 @@ QWeb.addDirective({
     if (!nodeTemplate) {
       throw new Error(`Cannot find template "${subTemplate}" (t-call)`);
     }
-    const nodeCopy = node.cloneNode(true) as Element;
-    nodeCopy.removeAttribute("t-call");
 
-    // extract variables from nodecopy
-    const tempCtx = new CompilationContext();
-    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;
-
-    const templateMap = Object.create(ctx.templates);
-    // open new scope, if necessary
-    const hasNewVariables = Object.keys(tempCtx.variables).length > 0;
-
-    // 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.recursiveFns['${subTemplateName}'].call(this, context, Object.assign({}, extra, {parentNode: c${ctx.parentNode}, fiber: {vars: ${varCode}, scope}}));`
-      );
-      return true;
+    // 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;
     }
-    templateMap[subTemplate] = true;
 
-    if (hasNewVariables) {
-      ctx.addLine("{");
+    // 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();
-      // 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} = ${(<QWebExprVar>v).expr};`);
-        }
-        // todo: handle XML variables...
-      }
-    }
-    qweb._compileNode(nodeTemplate.elem, subCtx);
-
-    // close new scope
-    if (hasNewVariables) {
+      protectID = ctx.startProtectScope();
+      const nodeCopy = node.cloneNode(true) as Element;
+      nodeCopy.removeAttribute("t-call");
+      const parentNode = ctx.parentNode;
+      ctx.parentNode = "__0";
+      // this local scope is intended to trap c__0
+      ctx.addLine(`{`);
+      ctx.indent();
+      ctx.addLine("let c__0 = [];");
+      qweb._compileNode(nodeCopy, ctx);
+      ctx.rootContext.shouldDefineUtils = true;
+      ctx.addLine("scope[utils.zero] = c__0;");
+      ctx.parentNode = parentNode;
       ctx.dedent();
-      ctx.addLine("}");
+      ctx.addLine(`}`);
+    }
+
+    // Step 4: add the appropriate function call to current component
+    // ------------------------------------------------
+    const callingScope = hasBody ? "scope" : "Object.assign(Object.create(context), scope)";
+    if (ctx.parentNode) {
+      ctx.addLine(
+        `this.subTemplates['${subTemplate}'].call(this, ${callingScope}, Object.assign({}, extra, {parentNode: c${ctx.parentNode}}));`
+      );
+    } 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]`);
+    }
+
+    // Step 5: restore previous scope
+    // ------------------------------------------------
+    if (hasBody) {
+      ctx.stopProtectScope(protectID);
+      ctx.dedent();
+      ctx.addLine(`}`);
     }
 
     return true;
@@ -270,7 +294,7 @@ QWeb.addDirective({
   extraNames: ["as"],
   priority: 10,
   atNodeEncounter({ node, qweb, ctx }): boolean {
-    ctx.rootContext.shouldProtectContext = true;
+    ctx.rootContext.shouldDefineScope = true;
     ctx = ctx.subContext("loopNumber", ctx.loopNumber + 1);
     const elems = node.getAttribute("t-foreach")!;
     const name = node.getAttribute("t-as")!;
@@ -285,14 +309,16 @@ 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}; ${loopVar}++) {`);
     ctx.indent();
-    ctx.addToScope(name + "_first", `${loopVar} === 0`);
-    ctx.addToScope(name + "_last", `${loopVar} === _length${keysID} - 1`);
-    ctx.addToScope(name + "_index", loopVar);
-    ctx.addToScope(name, `_${keysID}[${loopVar}]`);
-    ctx.addToScope(name + "_value", `_${valuesID}[${loopVar}]`);
+
+    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}]`);
     const nodeCopy = <Element>node.cloneNode(true);
     let shouldWarn =
       !nodeCopy.hasAttribute("t-key") &&
@@ -309,6 +335,7 @@ QWeb.addDirective({
     qweb._compileNode(nodeCopy, ctx);
     ctx.dedent();
     ctx.addLine("}");
+    ctx.stopProtectScope(varsID);
     return true;
   }
 });

src/qweb/compilation_context.ts

@@ -1,4 +1,4 @@
-import { compileExpr, QWebVar, QWebExprVar } from "./expression_parser";
+import { compileExpr, QWebVar } from "./expression_parser";
 
 export const INTERP_REGEXP = /\{\{.*?\}\}/g;
 //------------------------------------------------------------------------------
@@ -6,75 +6,73 @@ export const INTERP_REGEXP = /\{\{.*?\}\}/g;
 //------------------------------------------------------------------------------
 
 export class CompilationContext {
-  nextID: number = 1;
+  static nextID: number = 1;
   code: string[] = [];
   variables: { [key: string]: QWebVar } = {};
   escaping: boolean = false;
-  parentNode: number | null = null;
+  parentNode: number | null | string = null;
   parentTextNode: number | null = null;
   rootNode: number | null = null;
   indentLevel: number = 0;
   rootContext: CompilationContext;
-  caller: Element | undefined;
-  shouldDefineOwner: boolean = false;
   shouldDefineParent: boolean = false;
+  shouldDefineScope: boolean = false;
   shouldDefineQWeb: boolean = false;
   shouldDefineUtils: boolean = false;
   shouldDefineRefs: boolean = false;
   shouldDefineResult: boolean = true;
-  shouldDefineSibling: boolean = true;
-  shouldProtectContext: boolean = false;
-  shouldTrackScope: boolean = false;
   loopNumber: number = 0;
   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 {
-    const id = this.rootContext.nextID++;
-    return id;
+    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}`;
   }
 
   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.shouldDefineSibling) {
-      this.code.unshift("    let sibling = null;");
+
+    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;");
@@ -128,11 +126,6 @@ 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();
@@ -149,7 +142,7 @@ export class CompilationContext {
     this.addLine("}");
   }
 
-  getValue(val: any): QWebExprVar | string {
+  getValue(val: any): QWebVar | string {
     return val in this.variables ? this.getValue(this.variables[val]) : val;
   }
 
@@ -160,6 +153,7 @@ export class CompilationContext {
    * - replace already defined variables by their internal name
    */
   formatExpression(expr: string): string {
+    this.rootContext.shouldDefineScope = true;
     return compileExpr(expr, this.variables);
   }
 
@@ -180,4 +174,14 @@ 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};`);
+  }
 }

src/qweb/expression_parser.ts

@@ -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,typeof,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,eval,void,Math,RegExp,Array,Object,Date".split(
   ","
 );
 
@@ -38,17 +38,13 @@ const WORD_REPLACEMENT = {
   lte: "<="
 };
 
-export interface QWebExprVar {
-  id: string;
-  expr: string;
+export interface QWebVar {
+  id: string; // foo
+  expr: string; // scope.foo (local variables => only foo)
+  value?: string; // 1 + 3
+  hasBody?: boolean;
 }
 
-export interface QWebXMLVar {
-  xml: NodeList;
-}
-
-export type QWebVar = QWebExprVar | QWebXMLVar;
-
 //------------------------------------------------------------------------------
 // Tokenizer
 //------------------------------------------------------------------------------
@@ -68,6 +64,7 @@ type TKind =
 interface Token {
   type: TKind;
   value: string;
+  originalValue?: string;
   size?: number;
 }
 
@@ -82,7 +79,9 @@ const STATIC_TOKEN_MAP: { [key: string]: TKind } = {
   ")": "RIGHT_PAREN"
 };
 
-const OPERATORS = ".,===,==,+,!==,!=,!,||,&&,>=,>,<=,<,?,-,*,/,%".split(",");
+// note that the space after typeof is relevant. It makes sure that the formatted
+// expression has a space after typeof
+const OPERATORS = ".,===,==,+,!==,!=,!,||,&&,>=,>,<=,<,?,-,*,/,%,typeof ,=>".split(",");
 
 type Tokenizer = (expr: string) => Token | false;
 
@@ -165,9 +164,9 @@ const tokenizeOperator: Tokenizer = function(expr) {
 const TOKENIZERS = [
   tokenizeString,
   tokenizeNumber,
+  tokenizeOperator,
   tokenizeSymbol,
-  tokenizeStatic,
-  tokenizeOperator
+  tokenizeStatic
 ];
 
 /**
@@ -230,35 +229,53 @@ 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, vars: { [key: string]: QWebVar }): string {
+export function compileExpr(expr: string, scope: { [key: string]: QWebVar }): string {
+  scope = Object.create(scope);
   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 (isVar) {
-        if (token.value in vars && "id" in vars[token.value]) {
-          token.value = (<QWebExprVar>vars[token.value]).id;
-        } else {
-          token.value = `context['${token.value}']`;
+    }
+    if (nextToken && nextToken.type === "OPERATOR" && nextToken.value === "=>") {
+      if (token.type === "RIGHT_PAREN") {
+        let j = i - 1;
+        while (j > 0 && tokens[j].type !== "LEFT_PAREN") {
+          if (tokens[j].type === "SYMBOL" && tokens[j].originalValue) {
+            tokens[j].value = tokens[j].originalValue!;
+            scope[tokens[j].value] = { id: tokens[j].value, expr: tokens[j].value };
+          }
+          j--;
         }
+      } else {
+        scope[token.value] = { id: token.value, expr: token.value };
+      }
+    }
+
+    if (isVar) {
+      if (token.value in scope && "id" in scope[token.value]) {
+        token.value = scope[token.value].expr!;
+      } else {
+        token.originalValue = token.value;
+        token.value = `scope['${token.value}']`;
       }
     }
-    result += token.value;
   }
-  return result;
+  return tokens.map(t => t.value).join("");
 }

src/qweb/extensions.ts

@@ -30,7 +30,6 @@ 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");
@@ -40,8 +39,8 @@ QWeb.addDirective({
       extraArgs = args.slice(1, -1);
       return "";
     });
-    let params = extraArgs ? `owner, ${ctx.formatExpression(extraArgs)}` : "owner";
-    let handler = `function (e) {`;
+    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];
@@ -105,6 +104,8 @@ 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");
@@ -123,6 +124,9 @@ 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();
@@ -190,9 +194,8 @@ QWeb.addDirective({
 QWeb.addDirective({
   name: "slot",
   priority: 80,
-  atNodeEncounter({ ctx, value }): boolean {
+  atNodeEncounter({ ctx, value, node, qweb }): boolean {
     const slotKey = ctx.generateID();
-    ctx.rootContext.shouldDefineOwner = true;
     ctx.addLine(
       `const slot${slotKey} = this.constructor.slots[context.__owl__.slotId + '_' + '${value}'];`
     );
@@ -201,16 +204,22 @@ QWeb.addDirective({
     if (!ctx.parentNode) {
       ctx.rootContext.shouldDefineResult = true;
       ctx.rootContext.shouldDefineUtils = true;
-      parentNode = `children${ctx.nextID++}`;
+      parentNode = `children${ctx.generateID()}`;
       ctx.addLine(`let ${parentNode}= []`);
       ctx.addLine(`result = {}`);
     }
     ctx.addLine(
-      `slot${slotKey}.call(this, context.__owl__.parent, Object.assign({}, extra, {parentNode: ${parentNode}, vars: extra.vars, parent: owner}));`
+      `slot${slotKey}.call(this, context.__owl__.scope, Object.assign({}, extra, {parentNode: ${parentNode}, parent: extra.parent || context}));`
     );
     if (!ctx.parentNode) {
       ctx.addLine(`utils.defineProxy(result, ${parentNode}[0]);`);
     }
+    if (node.hasChildNodes()) {
+      ctx.addElse();
+      const nodeCopy = <Element>node.cloneNode(true);
+      nodeCopy.removeAttribute("t-slot");
+      qweb._compileNode(nodeCopy, ctx);
+    }
     ctx.closeIf();
     return true;
   }
@@ -231,7 +240,17 @@ QWeb.addDirective({
     const type = node.getAttribute("type");
     let handler;
     let event = fullName.includes(".lazy") ? "change" : "input";
-    const expr = ctx.formatExpression(value);
+
+    // we keep here a reference to the "base expression" (if the expression
+    // is `t-model="some.expr.value", then the base expression is "some.expr").
+    // This is necessary so we can capture it in the handler closure.
+    let expr = ctx.formatExpression(value);
+    const index = expr.lastIndexOf(".");
+    const baseExpr = expr.slice(0, index);
+    ctx.addLine(`let expr${nodeID} = ${baseExpr};`);
+
+    expr = `expr${nodeID}.${expr.slice(index + 1)}`;
+    const key = ctx.generateTemplateKey();
     if (node.tagName === "select") {
       ctx.addLine(`p${nodeID}.props = {value: ${expr}};`);
       addNodeHook("create", `n.elm.value=${expr};`);
@@ -255,10 +274,8 @@ QWeb.addDirective({
       }
       handler = `(ev) => {${expr} = ${valueCode}}`;
     }
-    ctx.addLine(
-      `extra.handlers['${event}' + ${nodeID}] = extra.handlers['${event}' + ${nodeID}] || (${handler});`
-    );
-    ctx.addLine(`p${nodeID}.on['${event}'] = extra.handlers['${event}' + ${nodeID}];`);
+    ctx.addLine(`extra.handlers[${key}] = extra.handlers[${key}] || (${handler});`);
+    ctx.addLine(`p${nodeID}.on['${event}'] = extra.handlers[${key}];`);
   }
 });
 
@@ -271,6 +288,6 @@ QWeb.addDirective({
   atNodeEncounter({ ctx, value }) {
     let id = ctx.generateID();
     ctx.addLine(`const nodeKey${id} = ${ctx.formatExpression(value)};`);
-    ctx.lastNodeKey = `nodeKey${id}`;
+    ctx.currentKey = `nodeKey${id}`;
   }
 });

src/qweb/qweb.ts

@@ -87,6 +87,7 @@ interface Utils {
 }
 
 const UTILS: Utils = {
+  zero: Symbol("zero"),
   toObj(expr) {
     if (typeof expr === "string") {
       expr = expr.trim();
@@ -105,6 +106,20 @@ 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();
   }
 };
 
@@ -171,7 +186,7 @@ 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.
-  recursiveFns = {};
+  subTemplates = {};
 
   isUpdating: boolean = false;
   translateFn?: QWebConfig["translateFn"];
@@ -360,24 +375,12 @@ export class QWeb extends EventBus {
       ctx.shouldDefineResult = false;
     }
     if (parentContext) {
-      ctx.templates = Object.create(parentContext.templates);
       ctx.variables = Object.create(parentContext.variables);
-      ctx.nextID = parentContext.nextID + 1;
-      ctx.parentNode = parentContext.parentNode || ctx.nextID++;
+      ctx.parentNode = parentContext.parentNode || ctx.generateID();
       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);
 
@@ -393,12 +396,13 @@ 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();
@@ -454,12 +458,19 @@ 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;
 
@@ -540,7 +551,6 @@ 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] || [];
@@ -644,13 +654,14 @@ export class QWeb extends EventBus {
       if (!name.startsWith("t-") && !(<Element>node).getAttribute("t-attf-" + name)) {
         const attID = ctx.generateID();
         if (name === "class") {
-          let classDef = value
-            .trim()
-            .split(/\s+/)
-            .map(a => `'${a}':true`)
-            .join(",");
-          classObj = `_${ctx.generateID()}`;
-          ctx.addLine(`let ${classObj} = {${classDef}};`);
+          if ((value = value.trim())) {
+            let classDef = value
+              .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]+$/)) {
@@ -666,7 +677,7 @@ export class QWeb extends EventBus {
       if (name.startsWith("t-att-")) {
         let attName = name.slice(6);
         const v = ctx.getValue(value);
-        let formattedValue = typeof v === "string" ? ctx.formatExpression(v) : v.id;
+        let formattedValue = typeof v === "string" ? ctx.formatExpression(v) : `scope.${v.id}`;
 
         if (attName === "class") {
           ctx.rootContext.shouldDefineUtils = true;
@@ -724,7 +735,7 @@ export class QWeb extends EventBus {
       }
     }
     let nodeID = ctx.generateID();
-    let nodeKey = ctx.lastNodeKey || nodeID;
+    let nodeKey = ctx.currentKey || nodeID;
     const parts = [`key:${nodeKey}`];
     if (attrs.length + tattrs.length > 0) {
       parts.push(`attrs:{${attrs.join(",")}}`);

src/store.ts

@@ -77,58 +77,70 @@ export class Store extends Context {
 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) || result;
+  let revNumber = hashFn(result);
   const isEqual = options.isEqual || isStrictEqual;
-  if (!store.updateFunctions[component.__owl__.id]) {
-    store.updateFunctions[component.__owl__.id] = [];
+  if (!store.updateFunctions[componentId]) {
+    store.updateFunctions[componentId] = [];
   }
-  const updateFunctions = store.updateFunctions[component.__owl__.id];
-  updateFunctions.push(function(): boolean {
+  function selectCompareUpdate(state, props): boolean {
     const oldResult = result;
-    result = selector(store!.state, component.props);
+    result = selector(state, props);
     const newRevNumber = hashFn(result);
-    if (
-      (newRevNumber > 0 && revNumber !== newRevNumber) ||
-      (newRevNumber === 0 && !isEqual(oldResult, 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;
-    updateFunctions.forEach(function(updateFn) {
-      shouldRender = updateFn() || shouldRender;
-    });
+    for (let fn of store.updateFunctions[componentId]) {
+      shouldRender = fn() || shouldRender;
+    }
     if (shouldRender) {
       return component.render();
     }
   });
   onWillUpdateProps(props => {
-    delete store.updateFunctions[component.__owl__.id];
-    result = selector(store.state, 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) {
-      result[k] = v;
-      return true;
+      throw new Error("Store state should only be modified through actions");
     }
   });
 }

src/vdom/html_to_vdom.ts

@@ -20,10 +20,8 @@ function htmlToVNode(node: ChildNode): VNode {
     attrs[attr.name] = attr.textContent;
   }
   const children: VNode[] = [];
-  if (node.hasChildNodes) {
-    for (let c of node.childNodes) {
-      children.push(htmlToVNode(c));
-    }
+  for (let c of node.childNodes) {
+    children.push(htmlToVNode(c));
   }
   return h((node as Element).tagName, { attrs }, children);
 }

src/vdom/modules.ts

@@ -219,7 +219,7 @@ function updateClass(oldVnode: VNode, vnode: VNode): void {
   elm = vnode.elm as Element;
 
   for (name in oldClass) {
-    if (!klass[name]) {
+    if (name && !klass[name]) {
       elm.classList.remove(name);
     }
   }

src/vdom/vdom.ts

@@ -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>;
 
@@ -176,10 +176,12 @@ 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 =
-        isDef(data) && isDef((i = (data as VNodeData).ns))
-          ? api.createElementNS(i, sel)
-          : api.createElement(sel));
+      const elm =
+        vnode.elm ||
+        (vnode.elm =
+          isDef(data) && isDef((i = (data as VNodeData).ns))
+            ? api.createElementNS(i, sel)
+            : api.createElement(sel));
       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) {

tests/__snapshots__/animations.test.ts.snap

@@ -1,100 +1,149 @@
 // 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 owner = context;
-    let sibling = null;
+    let scope = Object.create(context);
     var h = this.h;
     let c1 = [], p1 = {key:1};
     var vn1 = h('div', p1, c1);
     //COMPONENT
-    let templateId3 = \`__4__\`;
-    let w3 = templateId3 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[templateId3]] : false;
-    let props3 = {};
-    if (w3 && w3.__owl__.currentFiber && !w3.__owl__.vnode) {
-        w3.destroy();
-        w3 = false;
+    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 (w3) {
-        w3.__updateProps(props3, extra.fiber, undefined, undefined, sibling);
-        let pvnode = w3.__owl__.pvnode;
+    if (w2) {
+        w2.__updateProps(props2, extra.fiber, undefined);
+        let pvnode = w2.__owl__.pvnode;
         c1.push(pvnode);
     } else {
-        let componentKey3 = \`Child\`;
-        let W3 = context.constructor.components[componentKey3] || QWeb.components[componentKey3]|| context['Child'];
-        if (!W3) {throw new Error('Cannot find the definition of component \\"' + componentKey3 + '\\"')}
-        w3 = new W3(parent, props3);
-        parent.__owl__.cmap[templateId3] = w3.__owl__.id;
-        let def2 = w3.__prepare(extra.fiber, undefined, undefined, sibling);
-        let pvnode = h('dummy', {key: templateId3, hook: {insert(vn) { let nvn=w3.__mount(fiber, pvnode.elm);pvnode.elm=nvn.elm;utils.transitionInsert(vn, 'chimay');},remove() {},destroy(vn) {let finalize = () => {
-          w3.destroy();
+        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);}}});
-        const fiber = w3.__owl__.currentFiber;
-        def2.then(function () {if (fiber.isCancelled) {return;} const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
         c1.push(pvnode);
-        w3.__owl__.pvnode = pvnode;
+        w2.__owl__.pvnode = pvnode;
     }
-    sibling = w3.__owl__.currentFiber || sibling;
+    w2.__owl__.parentLastFiberId = extra.fiber.id;
     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 owner = context;
-    let sibling = null;
+    let scope = Object.create(context);
     var h = this.h;
     let c1 = [], p1 = {key:1};
     var vn1 = h('div', p1, c1);
-    if (context['state'].display) {
+    if (scope['state'].display) {
         //COMPONENT
-        let templateId3 = \`__4__\`;
-        let w3 = templateId3 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[templateId3]] : false;
-        let props3 = {};
-        if (w3 && w3.__owl__.currentFiber && !w3.__owl__.vnode) {
-            w3.destroy();
-            w3 = false;
+        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 (w3) {
-            w3.__updateProps(props3, extra.fiber, undefined, undefined, sibling);
-            let pvnode = w3.__owl__.pvnode;
+        if (w2) {
+            w2.__updateProps(props2, extra.fiber, undefined);
+            let pvnode = w2.__owl__.pvnode;
             c1.push(pvnode);
         } else {
-            let componentKey3 = \`Child\`;
-            let W3 = context.constructor.components[componentKey3] || QWeb.components[componentKey3]|| context['Child'];
-            if (!W3) {throw new Error('Cannot find the definition of component \\"' + componentKey3 + '\\"')}
-            w3 = new W3(parent, props3);
-            parent.__owl__.cmap[templateId3] = w3.__owl__.id;
-            let def2 = w3.__prepare(extra.fiber, undefined, undefined, sibling);
-            let pvnode = h('dummy', {key: templateId3, hook: {insert(vn) { let nvn=w3.__mount(fiber, pvnode.elm);pvnode.elm=nvn.elm;utils.transitionInsert(vn, 'chimay');},remove() {},destroy(vn) {let finalize = () => {
-          w3.destroy();
+            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);}}});
-            const fiber = w3.__owl__.currentFiber;
-            def2.then(function () {if (fiber.isCancelled) {return;} const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
             c1.push(pvnode);
-            w3.__owl__.pvnode = pvnode;
+            w2.__owl__.pvnode = pvnode;
         }
-        sibling = w3.__owl__.currentFiber || sibling;
+        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);
+        } 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;
+        }
+        w2.__owl__.parentLastFiberId = extra.fiber.id;
     }
     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;
-    let sibling = null;
     var h = this.h;
     let c1 = [], p1 = {key:1};
     var vn1 = h('span', p1, c1);
@@ -112,10 +161,10 @@ 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;
-    let sibling = null;
     var h = this.h;
     let c1 = [], p1 = {key:1};
     var vn1 = h('span', p1, c1);

tests/animations.test.ts

@@ -1,13 +1,15 @@
 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
+  unpatchNextFrame,
+  nextTick
 } from "./helpers";
 
 //------------------------------------------------------------------------------
@@ -321,30 +323,23 @@ describe("animations", () => {
   });
 
   test("t-transition combined with t-component, remove and re-add before transitionend", async () => {
-    expect.assertions(11);
+    expect.assertions(12);
 
-    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>
-        <span t-name="Child">blue</span>
-      </templates>`
-    );
-    class Child extends Widget {}
+    class Child extends Widget {
+      static template = xml`<span>blue</span>`;
+    }
     class Parent extends Widget {
+      static template = xml`
+        <div t-name="Parent">
+          <t t-if="state.flag" t-component="Child" t-transition="chimay"/>
+        </div>`;
       static components = { Child };
       state = useState({ flag: false });
-
-      toggle() {
-        this.state.flag = !this.state.flag;
-      }
     }
 
     const widget = new Parent();
     await widget.mount(fixture);
-    let button = widget.el!.querySelector("button");
+    expect(env.qweb.templates[Parent.template].fn.toString()).toMatchSnapshot();
 
     let def = makeDeferred();
     let phase = "enter";
@@ -357,24 +352,78 @@ describe("animations", () => {
       def.resolve();
     });
 
-    // click display the span
-    button!.click();
+    // display the span
+    widget.state.flag = true;
     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><button>Toggle</button><span class="">blue</span></div>');
+    expect(fixture.innerHTML).toBe('<div><span class="">blue</span></div>');
 
     // click to remove the span, and click again to re-add it before transitionend
     def = makeDeferred();
     phase = "leave";
-    button!.click();
+
+    widget.state.flag = false;
 
     await def; // wait for the mocked repaint to be done
     def = makeDeferred();
     phase = "enter";
-    button!.click();
+    widget.state.flag = true;
 
     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><button>Toggle</button><span class="">blue</span></div>');
+    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;
   });
 });

tests/component/__snapshots__/props_validation.test.ts.snap

@@ -1,42 +1,40 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
 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 owner = context;
-    let sibling = null;
+    let scope = Object.create(context);
     var h = this.h;
     let c1 = [], p1 = {key:1};
     var vn1 = h('div', p1, c1);
     //COMPONENT
-    let templateId3 = \`__4__\`;
-    let w3 = templateId3 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[templateId3]] : false;
-    let props3 = {message:1};
-    if (w3 && w3.__owl__.currentFiber && !w3.__owl__.vnode) {
-        w3.destroy();
-        w3 = false;
+    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;
     }
-    if (w3) {
-        w3.__updateProps(props3, extra.fiber, undefined, undefined, sibling);
-        let pvnode = w3.__owl__.pvnode;
+    if (w2) {
+        w2.__updateProps(props2, extra.fiber, undefined);
+        let pvnode = w2.__owl__.pvnode;
         c1.push(pvnode);
     } else {
-        let componentKey3 = \`Child\`;
-        let W3 = context.constructor.components[componentKey3] || QWeb.components[componentKey3]|| context['Child'];
-        if (!W3) {throw new Error('Cannot find the definition of component \\"' + componentKey3 + '\\"')}
-        w3 = new W3(parent, props3);
-        parent.__owl__.cmap[templateId3] = w3.__owl__.id;
-        let def2 = w3.__prepare(extra.fiber, undefined, undefined, sibling);
-        let pvnode = h('dummy', {key: templateId3, hook: {insert(vn) { let nvn=w3.__mount(fiber, pvnode.elm);pvnode.elm=nvn.elm;},remove() {},destroy(vn) {w3.destroy();}}});
-        const fiber = w3.__owl__.currentFiber;
-        def2.then(function () {if (fiber.isCancelled) {return;} const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
+        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);
-        w3.__owl__.pvnode = pvnode;
+        w2.__owl__.pvnode = pvnode;
     }
-    sibling = w3.__owl__.currentFiber || sibling;
+    w2.__owl__.parentLastFiberId = extra.fiber.id;
     return vn1;
 }"
 `;

tests/component/props_validation.test.ts

@@ -138,7 +138,7 @@ describe("props validation", () => {
         error = e;
       }
       expect(error).toBeDefined();
-      expect(error.message).toBe(`Props 'p' of invalid type in component '_a'`);
+      expect(error.message).toBe("Invalid Prop 'p' in component '_a'");
     }
   });
 
@@ -195,7 +195,7 @@ describe("props validation", () => {
         error = e;
       }
       expect(error).toBeDefined();
-      expect(error.message).toBe(`Props 'p' of invalid type in component '_a'`);
+      expect(error.message).toBe("Invalid Prop 'p' in component '_a'");
     }
   });
 
@@ -240,7 +240,7 @@ describe("props validation", () => {
       error = e;
     }
     expect(error).toBeDefined();
-    expect(error.message).toBe("Props 'p' of invalid type in component 'TestWidget'");
+    expect(error.message).toBe("Invalid Prop 'p' in component 'TestWidget'");
   });
 
   test("can validate an optional props", async () => {
@@ -284,7 +284,7 @@ describe("props validation", () => {
       error = e;
     }
     expect(error).toBeDefined();
-    expect(error.message).toBe(`Props 'p' of invalid type in component 'TestWidget'`);
+    expect(error.message).toBe("Invalid Prop 'p' in component 'TestWidget'");
   });
 
   test("can validate an array with given primitive type", async () => {
@@ -389,7 +389,7 @@ describe("props validation", () => {
       error = e;
     }
     expect(error).toBeDefined();
-    expect(error.message).toBe(`Props 'p' of invalid type in component 'TestWidget'`);
+    expect(error.message).toBe("Invalid Prop 'p' in component 'TestWidget'");
   });
 
   test("can validate an object with simple shape", async () => {
@@ -436,7 +436,7 @@ describe("props validation", () => {
       error = e;
     }
     expect(error).toBeDefined();
-    expect(error.message).toBe(`Props 'p' of invalid type in component 'TestWidget'`);
+    expect(error.message).toBe("Invalid Prop 'p' in component 'TestWidget'");
 
     error = undefined;
     try {
@@ -447,7 +447,7 @@ describe("props validation", () => {
       error = e;
     }
     expect(error).toBeDefined();
-    expect(error.message).toBe(`Props 'p' of invalid type in component 'TestWidget'`);
+    expect(error.message).toBe("Invalid Prop 'p' in component 'TestWidget'");
   });
 
   test("can validate recursively complicated prop def", async () => {
@@ -499,7 +499,7 @@ describe("props validation", () => {
       error = e;
     }
     expect(error).toBeDefined();
-    expect(error.message).toBe(`Props 'p' of invalid type in component 'TestWidget'`);
+    expect(error.message).toBe("Invalid Prop 'p' in component 'TestWidget'");
   });
 
   test("can validate optional attributes in nested sub props", () => {
@@ -535,6 +535,70 @@ describe("props validation", () => {
     );
   });
 
+  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);
+  });
+
   test("props are validated in dev mode (code snapshot)", async () => {
     env.qweb.addTemplates(`
       <templates>
@@ -581,6 +645,32 @@ 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"];

tests/context.test.ts

@@ -106,7 +106,7 @@ describe("Context", () => {
     expect(fixture.innerHTML).toBe("<div><span>321</span><span>321</span></div>");
   });
 
-  test("two async components on two levels are updated in parallel", async () => {
+  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[] = [];
@@ -151,6 +151,11 @@ describe("Context", () => {
     );
     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>"
@@ -255,6 +260,35 @@ describe("Context", () => {
     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();

tests/core/observer.test.ts

@@ -408,7 +408,7 @@ describe("observer", () => {
     obj.a = 111;
     obj.f = 222;
     await nextMicroTick();
-    expect(observer.notifyCB).toBeCalledTimes(4);
+    expect(observer.notifyCB).toBeCalledTimes(5);
   });
 
   test("throw error when state is mutated in object if allowMutation=false", async () => {

tests/helpers.ts

@@ -1,6 +1,7 @@
 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";
@@ -20,6 +21,7 @@ let TEMPLATES;
 
 beforeEach(() => {
   nextSlotId = QWeb.nextSlotId;
+  CompilationContext.nextID = 1;
   slots = Object.assign({}, QWeb.slots);
   nextId = QWeb.nextId;
   TEMPLATES = Object.assign({}, QWeb.TEMPLATES);
@@ -85,6 +87,11 @@ 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

tests/misc/portal.test.ts

@@ -0,0 +1,890 @@
+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();
+  });
+});

tests/qweb/qweb.test.ts

@@ -46,6 +46,16 @@ 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>");
@@ -129,6 +139,17 @@ 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", () => {
@@ -242,6 +263,82 @@ 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", () => {
@@ -406,6 +503,18 @@ 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 });
@@ -550,10 +659,19 @@ 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", () => {
@@ -561,6 +679,7 @@ 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", () => {
@@ -645,6 +764,41 @@ 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", () => {
@@ -660,7 +814,7 @@ describe("t-call (template calling", () => {
     `);
     const expected = "<div><span>hey</span></div>";
     expect(renderToString(qweb, "recursive")).toBe(expected);
-    const recursiveFn = Object.values(qweb.recursiveFns)[0] as any;
+    const recursiveFn = Object.values(qweb.subTemplates)[0] as any;
     expect(recursiveFn.toString()).toMatchSnapshot();
   });
 
@@ -688,7 +842,7 @@ describe("t-call (template calling", () => {
     expect(renderToString(qweb, "Parent", { root }, { fiber: { vars: {}, scope: {} } })).toBe(
       expected
     );
-    const recursiveFn = Object.values(qweb.recursiveFns)[0] as any;
+    const recursiveFn = Object.values(qweb.subTemplates)[0] as any;
     expect(recursiveFn.toString()).toMatchSnapshot();
   });
 
@@ -715,7 +869,7 @@ 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.recursiveFns)[0] as any;
+    const recursiveFn = Object.values(qweb.subTemplates)[0] as any;
     expect(recursiveFn.toString()).toMatchSnapshot();
   });
 
@@ -725,6 +879,51 @@ 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", () => {
@@ -793,9 +992,9 @@ describe("foreach", () => {
         <t t-foreach="[1]" t-as="item"><t t-esc="item"/></t>
       </div>`
     );
-    const context = {};
+    const context = { __owl__: {} };
     renderToString(qweb, "test", context);
-    expect(Object.keys(context).length).toBe(0);
+    expect(Object.keys(context)).toEqual(["__owl__"]);
   });
 
   test("t-foreach in t-forach", () => {
@@ -1199,7 +1398,10 @@ describe("t-on", () => {
     );
     const steps: string[] = [];
     const owner = {
-      projects: [{ id: 1, name: "Project 1" }, { id: 2, name: "Project 2" }],
+      projects: [
+        { id: 1, name: "Project 1" },
+        { id: 2, name: "Project 2" }
+      ],
 
       onEdit(projectId, ev) {
         expect(ev.defaultPrevented).toBe(true);
@@ -1451,6 +1653,22 @@ 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();

tests/qweb/qweb_expressions.test.ts

@@ -27,7 +27,10 @@ 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: "[" }
@@ -43,6 +46,10 @@ describe("tokenizer", () => {
       { type: "OPERATOR", value: "!==" },
       { type: "OPERATOR", value: "!=" }
     ]);
+    expect(tokenize("typeof a")).toEqual([
+      { type: "OPERATOR", value: "typeof " },
+      { type: "SYMBOL", value: "a" }
+    ]);
   });
 
   test("strings", () => {
@@ -85,7 +92,7 @@ describe("expression evaluation", () => {
 
   test("parenthesis", () => {
     expect(compileExpr("(1)", {})).toBe("(1)");
-    expect(compileExpr("a*(1 +3)", {})).toBe("context['a']*(1+3)");
+    expect(compileExpr("a*(1 +3)", {})).toBe("scope['a']*(1+3)");
   });
 
   test("objects and sub objects", () => {
@@ -93,8 +100,8 @@ describe("expression evaluation", () => {
   });
 
   test("replacing variables", () => {
-    expect(compileExpr("a", {})).toBe("context['a']");
-    expect(compileExpr("a", { a: { id: "_3", expr: "" } })).toBe("_3");
+    expect(compileExpr("a", {})).toBe("scope['a']");
+    expect(compileExpr("a", { a: { id: "_3", expr: "scope._3" } })).toBe("scope._3");
   });
 
   test("arrays and objects", () => {
@@ -104,55 +111,63 @@ describe("expression evaluation", () => {
   });
 
   test("dot operator", () => {
-    expect(compileExpr("a.b", {})).toBe("context['a'].b");
-    expect(compileExpr("a.b.c", {})).toBe("context['a'].b.c");
+    expect(compileExpr("a.b", {})).toBe("scope['a'].b");
+    expect(compileExpr("a.b.c", {})).toBe("scope['a'].b.c");
   });
 
   test("various unary operators", () => {
-    expect(compileExpr("!flag", {})).toBe("!context['flag']");
+    expect(compileExpr("!flag", {})).toBe("!scope['flag']");
     expect(compileExpr("-3", {})).toBe("-3");
-    expect(compileExpr("-a", {})).toBe("-context['a']");
+    expect(compileExpr("-a", {})).toBe("-scope['a']");
+    expect(compileExpr("typeof a", {})).toBe("typeof scope['a']");
   });
 
   test("various binary operators", () => {
-    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");
+    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");
   });
 
   test("boolean operations", () => {
-    expect(compileExpr("a && b", {})).toBe("context['a']&&context['b']");
+    expect(compileExpr("a && b", {})).toBe("scope['a']&&scope['b']");
   });
 
   test("ternary operators", () => {
-    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 ? 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 ? {test:c}: [1,u]", {})).toBe(
-      "context['a']?{test:context['c']}:[1,context['u']]"
+      "scope['a']?{test:scope['c']}:[1,scope['u']]"
     );
   });
 
   test("word replacement", () => {
-    expect(compileExpr("a or b", {})).toBe("context['a']||context['b']");
-    expect(compileExpr("a and b", {})).toBe("context['a']&&context['b']");
+    expect(compileExpr("a or b", {})).toBe("scope['a']||scope['b']");
+    expect(compileExpr("a and b", {})).toBe("scope['a']&&scope['b']");
   });
 
   test("function calls", () => {
-    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("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("'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: "" } })).toBe(
-      "'x'.toUpperCase(_v5)"
+    expect(compileExpr("'x'.toUpperCase(a)", { a: { id: "_v5", expr: "scope._v5" } })).toBe(
+      "'x'.toUpperCase(scope._v5)"
     );
-    expect(compileExpr("'x'.toUpperCase({b: a})", { a: { id: "_v5", expr: "" } })).toBe(
-      "'x'.toUpperCase({b:_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)"
     );
   });
 });

tests/router/__snapshots__/link.test.ts.snap

@@ -1,22 +1,22 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
 exports[`Link component can render simple cases 1`] = `
-"function anonymous(context,extra
+"function anonymous(context, extra
 ) {
+    // Template name: \\"__template__1\\"
     let utils = this.constructor.utils;
-    let owner = context;
-    let sibling = null;
+    let scope = Object.create(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);
-    extra.handlers['click' + 3] = extra.handlers['click' + 3] || function (e) {const fn = context['navigate'];if (fn) { fn.call(owner, e); } else { context.navigate; }};
-    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}));
+    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 vn3;
+    return vn7;
 }"
 `;

tests/router/__snapshots__/route_component.test.ts.snap

@@ -1,45 +1,43 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
 exports[`RouteComponent can render simple cases 1`] = `
-"function anonymous(context,extra
+"function anonymous(context, extra
 ) {
+    // Template name: \\"__template__1\\"
     let utils = this.constructor.utils;
     let QWeb = this.constructor;
     let parent = context;
-    let owner = context;
-    let sibling = null;
+    let scope = Object.create(context);
     let result;
     var h = this.h;
-    if (context['routeComponent']) {
-        const nodeKey1 = context['env'].router.currentRouteName;
+    if (scope['routeComponent']) {
+        const nodeKey5 = scope['env'].router.currentRouteName;
         //COMPONENT
-        let templateId3 = \`__4__\` + nodeKey1;
-        let w3 = templateId3 in parent.__owl__.cmap ? parent.__owl__.children[parent.__owl__.cmap[templateId3]] : false;
-        let vn5 = {};
-        result = vn5;
-        let props3 = Object.assign({}, context['env'].router.currentParams);
-        if (w3 && w3.__owl__.currentFiber && !w3.__owl__.vnode) {
-            w3.destroy();
-            w3 = false;
+        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 (w3) {
-            w3.__updateProps(props3, extra.fiber, undefined, undefined, sibling);
-            let pvnode = w3.__owl__.pvnode;
-            utils.defineProxy(vn5, pvnode);
+        if (w6) {
+            w6.__updateProps(props6, extra.fiber, undefined);
+            let pvnode = w6.__owl__.pvnode;
+            utils.defineProxy(vn9, pvnode);
         } else {
-            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[templateId3] = w3.__owl__.id;
-            let def2 = w3.__prepare(extra.fiber, undefined, undefined, sibling);
-            let pvnode = h('dummy', {key: templateId3, hook: {insert(vn) { let nvn=w3.__mount(fiber, pvnode.elm);pvnode.elm=nvn.elm;},remove() {},destroy(vn) {w3.destroy();}}});
-            const fiber = w3.__owl__.currentFiber;
-            def2.then(function () {if (fiber.isCancelled) {return;} const vnode = fiber.vnode; pvnode.sel = vnode.sel; });
-            utils.defineProxy(vn5, pvnode);
-            w3.__owl__.pvnode = pvnode;
+            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;
         }
-        sibling = w3.__owl__.currentFiber || sibling;
+        w6.__owl__.parentLastFiberId = extra.fiber.id;
     }
     return result;
 }"

tests/router/link.test.ts

@@ -35,7 +35,10 @@ 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" });
@@ -66,7 +69,10 @@ 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" });

tests/store_hooks.test.ts

@@ -48,6 +48,42 @@ describe("connecting a component to store", () => {
     expect(fixture.innerHTML).toBe("<div><span>hello</span></div>");
   });
 
+  test("useStore can observe primitive types and call onUpdate", async () => {
+    const state = { isBoolean: false };
+    const actions = {
+      setTrue({ state }) {
+        state.isBoolean = true;
+      }
+    };
+    const store = new Store({ state, actions });
+
+    class App extends Component<any, any> {
+      static template = xml`
+            <div>
+                <span t-if="isBoolean">ok</span>
+            </div>`;
+      isBoolean: boolean;
+      constructor() {
+        super();
+        this.isBoolean = useStore(state => state.isBoolean, {
+          onUpdate: isBoolean => {
+            this.isBoolean = isBoolean;
+          }
+        });
+      }
+    }
+
+    (<any>env).store = store;
+    const app = new App();
+
+    await app.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div></div>");
+
+    store.dispatch("setTrue");
+    await nextTick();
+    expect(fixture.innerHTML).toBe("<div><span>ok</span></div>");
+  });
+
   test("throw error if no store is found", async () => {
     class App extends Component<any, any> {
       static template = xml`<div></div>`;
@@ -64,6 +100,24 @@ describe("connecting a component to store", () => {
     expect(error.message).toBe("No store found when connecting 'App'");
   });
 
+  test("cannot modify state returned by usestore", async () => {
+    const state = { a: { b: 1 } };
+    const actions = {};
+    const store = new Store({ state, actions });
+
+    class App extends Component<any, any> {
+      static template = xml`<div/>`;
+      storeState = useStore(state => state.a);
+    }
+
+    (<any>env).store = store;
+    const app = new App();
+    expect(app.storeState.b).toBe(1);
+    expect(() => (app.storeState.b = 2)).toThrow(
+      "Store state should only be modified through actions"
+    );
+  });
+
   test("can use useStore twice in a component", async () => {
     const state = { a: 1, b: 2 };
     const actions = {
@@ -257,7 +311,12 @@ describe("connecting a component to store", () => {
   });
 
   test("useStore can use props", async () => {
-    const state = { todos: [{ id: 1, text: "jupiler" }, { id: 2, text: "chimay" }] };
+    const state = {
+      todos: [
+        { id: 1, text: "jupiler" },
+        { id: 2, text: "chimay" }
+      ]
+    };
     const store = new Store({ state, actions: {} });
 
     class TodoItem extends Component<any, any> {
@@ -324,7 +383,10 @@ describe("connecting a component to store", () => {
   test("can call useGetters to receive store getters", async () => {
     const state = {
       importantID: 1,
-      todos: [{ id: 1, text: "jupiler" }, { id: 2, text: "bertinchamps" }]
+      todos: [
+        { id: 1, text: "jupiler" },
+        { id: 2, text: "bertinchamps" }
+      ]
     };
     const getters = {
       importantTodoText({ state }) {
@@ -428,6 +490,68 @@ describe("connecting a component to store", () => {
     expect(fixture.innerHTML).toBe("<div><span>jupiler</span><span>kwak</span></div>");
   });
 
+  test("connected component is updated when mixing store and props changes", async () => {
+    let counter = 0;
+
+    class Beer extends Component<any, any> {
+      static template = xml`<span><t t-esc="beer.name"/></span>`;
+      beer = useStore((state, props) => state.beers[props.id], {
+        onUpdate: result => {
+          ++counter;
+        }
+      });
+    }
+
+    class App extends Component<any, any> {
+      static template = xml`<div><Beer id="state.beerId"/></div>`;
+      static components = { Beer };
+      state = useState({ beerId: 1 });
+    }
+
+    const state = { beers: { 1: { name: "jupiler" }, 2: { name: "kwak" } } };
+    const actions = {
+      renameBeer({ state }, { id, name }) {
+        state.beers[id].name = name;
+      }
+    };
+    const store = new Store({ state, actions });
+    (<any>env).store = store;
+    const app = new App();
+
+    await app.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div><span>jupiler</span></div>");
+    expect(counter).toBe(0);
+
+    app.state.beerId = 2;
+    await nextTick();
+    expect(fixture.innerHTML).toBe("<div><span>kwak</span></div>");
+    expect(counter).toBe(1);
+
+    store.dispatch("renameBeer", { id: 2, name: "orval" });
+    await nextTick();
+    expect(fixture.innerHTML).toBe("<div><span>orval</span></div>");
+    expect(counter).toBe(2);
+  });
+
+  test("connected component is properly cleaned up on destroy", async () => {
+    class App extends Component<any, any> {
+      static template = xml`<div></div>`;
+      state = useStore((state, props) => state);
+    }
+
+    const store = new Store({ state: {} });
+    (<any>env).store = store;
+    const app = new App();
+
+    await app.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div></div>");
+    expect(store.updateFunctions[app.__owl__.id].length).toBe(1);
+
+    app.destroy();
+
+    expect(store.updateFunctions[app.__owl__.id]).toBe(undefined);
+  });
+
   test("connected component with undefined, null and string props", async () => {
     class Beer extends Component<any, any> {
       static template = xml`
@@ -572,6 +696,31 @@ describe("connecting a component to store", () => {
     );
   });
 
+  test("store changes occuring when mounting a component are notified", async () => {
+    const initialState = { x: { val: 1 } };
+    const actions = {
+      setValue({ state }, val) {
+        state.x.val = val;
+      }
+    };
+    class Parent extends Component<any, any> {
+      static template = xml`<div><t t-esc="x.val"/></div>`;
+      x = useStore(state => {
+        return Object.assign({}, state.x);
+      });
+      dispatch = useDispatch();
+    }
+    Parent.prototype.__render = jest.fn(Parent.prototype.__render);
+    Parent.env.store = new Store({ state: initialState, actions });
+
+    const parent = new Parent();
+    const prom = parent.mount(fixture);
+    parent.dispatch("setValue", 2);
+    await prom;
+    expect(fixture.innerHTML).toBe("<div>2</div>");
+    expect(Parent.prototype.__render).toHaveBeenCalledTimes(1);
+  });
+
   test("correct update order when parent/children are connected", async () => {
     const steps: string[] = [];
 
@@ -899,6 +1048,46 @@ describe("connecting a component to store", () => {
     expect(steps).toEqual(["on:update", "off:update"]);
   });
 
+  test("connected child component destroyed by dispatched action", async () => {
+    let steps: any = [];
+
+    class Child extends Component<any, any> {
+      static template = xml`<div><t t-esc="store.val"/></div>`;
+      store = useStore(s => {
+        steps.push("child selector");
+        return s;
+      });
+    }
+    class Parent extends Component<any, any> {
+      static template = xml`<div><Child t-if="store.child" /></div>`;
+      static components = { Child };
+      store = useStore(s => {
+        steps.push("parent selector");
+        return s;
+      });
+      dispatch = useDispatch();
+    }
+
+    const state = { child: true, val: 1 };
+    const actions = {
+      toggleChild({ state }) {
+        state.child = !state.child;
+      }
+    };
+    const store = new Store({ state, actions });
+    (<any>env).store = store;
+    const parent = new Parent();
+
+    await parent.mount(fixture);
+    expect(fixture.innerHTML).toBe("<div><div>1</div></div>");
+    expect(steps).toEqual(["parent selector", "child selector"]);
+
+    parent.dispatch("toggleChild");
+    await nextTick();
+    expect(fixture.innerHTML).toBe("<div></div>");
+    expect(steps).toEqual(["parent selector", "child selector", "parent selector"]);
+  });
+
   test("dispatch an action", async () => {
     class App extends Component<any, any> {
       static template = xml`<div><t t-esc="store.counter"/></div>`;

tests/tooling/debug_script_1.test.ts

@@ -0,0 +1,57 @@
+/**
+ * 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;
+});

tests/tooling/debug_script_2.test.ts

@@ -0,0 +1,50 @@
+/**
+ * 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;
+});

tests/tooling/debug_script_3.test.ts

@@ -0,0 +1,46 @@
+/**
+ * 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;
+});

tests/tooling/doc_link_checker.test.ts

@@ -85,7 +85,7 @@ function getFiles(path: string[] = []): FileData[] {
   return Array.prototype.concat(...files);
 }
 
-const LOCAL_FILES = ["LICENSE"];
+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

tools/benchmarks/owl-0.10.0/app.js

@@ -1,173 +0,0 @@
-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();

tools/benchmarks/owl-0.10.0/index.html

@@ -1,13 +0,0 @@
-<!DOCTYPE html>
-<html lang="en">
-<head>
-  <meta charset="UTF-8">
-  <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>

tools/benchmarks/owl-0.10.0/templates.xml

@@ -1,50 +0,0 @@
-<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>

tools/benchmarks/owl-0.12.0/app.js

@@ -1,170 +0,0 @@
-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();

tools/benchmarks/owl-0.12.0/templates.xml

@@ -1,50 +0,0 @@
-<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>

tools/benchmarks/owl-0.14.0/index.html

@@ -1,13 +0,0 @@
-<!DOCTYPE html>
-<html lang="en">
-<head>
-  <meta charset="UTF-8">
-  <title>OWL 0.14.0 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>

tools/benchmarks/owl-0.14.0/templates.xml

@@ -1,50 +0,0 @@
-<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" message="message"/>
-              </t>
-          </div>
-      </div>
-  </div>
-
-  <div t-name="Message" class="message">
-    <span class="author"><t t-esc="props.message.author"/></span>
-    <span class="msg"><t t-esc="props.message.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>

tools/benchmarks/owl-0.16.0/app.js

@@ -1,161 +0,0 @@
-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 {
-  components = { Counter };
-
-  shouldUpdate(nextProps) {
-    return nextProps.message !== this.props.message;
-  }
-  removeMessage() {
-    this.trigger("remove-message", {
-      id: this.props.message.id
-    });
-  }
-}
-
-//------------------------------------------------------------------------------
-// Root Widget
-//------------------------------------------------------------------------------
-class App extends owl.Component {
-  components = { 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(event) {
-    this.benchmark("remove message", () => {
-      const index = this.state.messages.findIndex(m => m.id === event.detail.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();

tools/benchmarks/owl-0.16.0/index.html

@@ -1,13 +0,0 @@
-<!DOCTYPE html>
-<html lang="en">
-<head>
-  <meta charset="UTF-8">
-  <title>OWL 0.16.0 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>

tools/benchmarks/owl-0.24.0/index.html

@@ -4,7 +4,7 @@
   <meta charset="UTF-8">
   <title>OWL v0.24.0 Benchmark</title>
   <link href="../shared/main.css" rel="stylesheet"/>
-  <script src='../../owl.js'></script>
+  <script src='owl.js'></script>
 </head>
 <body>
   <script src='app.js' type="module"></script>

tools/benchmarks/owl-0.8.0/app.js

@@ -1,173 +0,0 @@
-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();

tools/benchmarks/owl-0.8.0/index.html

@@ -1,13 +0,0 @@
-<!DOCTYPE html>
-<html lang="en">
-<head>
-  <meta charset="UTF-8">
-  <title>OWL 0.8.0 Benchmark</title>
-  <link href="../shared/main.css" rel="stylesheet"/>
-  <script src='owl-0.8.0.js'></script>
-</head>
-<body>
-  <div id='main'></div>
-  <script src='app.js' type="module"></script>
-</body>
-</html>

tools/benchmarks/owl-0.8.0/templates.xml

@@ -1,50 +0,0 @@
-<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>

tools/benchmarks/owl-1.0.0-beta1/app.js

@@ -1,10 +1,11 @@
 import { buildData, startMeasure, stopMeasure, formatNumber } from "../shared/utils.js";
 
+const { useState, useRef } = owl.hooks;
 //------------------------------------------------------------------------------
 // Likes Counter Widget
 //------------------------------------------------------------------------------
 class Counter extends owl.Component {
-  state = { counter: 0 };
+  state = useState({ counter: 0 });
 
   increment() {
     this.state.counter++;
@@ -15,8 +16,6 @@ class Counter extends owl.Component {
 // Message Widget
 //------------------------------------------------------------------------------
 class Message extends owl.Component {
-  widgets = { Counter };
-
   shouldUpdate(nextProps) {
     return nextProps.message !== this.props.message;
   }
@@ -26,13 +25,14 @@ class Message extends owl.Component {
     });
   }
 }
+Message.components = { Counter };
 
 //------------------------------------------------------------------------------
 // Root Widget
 //------------------------------------------------------------------------------
 class App extends owl.Component {
-  widgets = { Message };
-  state = { messages: [], multipleFlag: false, clearAfterFlag: false };
+  state = useState({ messages: [], multipleFlag: false, clearAfterFlag: false });
+  logRef = useRef("log");
 
   mounted() {
     this.log(`Benchmarking Owl v${owl.__info__.version} (build date: ${owl.__info__.date})`);
@@ -108,10 +108,10 @@ class App extends owl.Component {
   updateSomeMessages() {
     this.benchmark("update every 10th", () => {
       const messages = this.state.messages;
-      for (let i = 0; i < this.state.messages.length; i += 10) {
+      for (let i = 0; i < messages.length; i += 10) {
         const msg = Object.assign({}, messages[i]);
         msg.author += "!!!";
-        this.set(messages, i, msg);
+        messages[i] = msg;
       }
     });
   }
@@ -129,32 +129,25 @@ class App extends owl.Component {
       div.classList.add("bold");
     }
     div.textContent = `> ${str}`;
-    this.refs.log.appendChild(div);
-    this.refs.log.scrollTop = this.refs.log.scrollHeight;
+    this.logRef.el.appendChild(div);
+    this.logRef.el.scrollTop = this.logRef.el.scrollHeight;
   }
 
   clearLog() {
-    this.refs.log.innerHTML = "";
-  }
-
-  toggleMultiple() {
-    this.state.multipleFlag = !this.state.multipleFlag;
-  }
-
-  toggleClear() {
-    this.state.clearAfterFlag = !this.state.clearAfterFlag;
+    this.logRef.el.innerHTML = "";
   }
 }
+App.components = { Message };
 
 //------------------------------------------------------------------------------
 // Application initialization
 //------------------------------------------------------------------------------
 async function start() {
-  const templates = await owl.utils.loadTemplates("templates.xml");
-  const env = {
-    qweb: new owl.QWeb(templates)
+  const templates = await owl.utils.loadFile("templates.xml");
+  App.env = {
+    qweb: new owl.QWeb({ templates })
   };
-  const app = new App(env);
+  const app = new App();
   app.mount(document.body);
 }
 

tools/benchmarks/owl-1.0.0-beta1/index.html

@@ -2,12 +2,11 @@
 <html lang="en">
 <head>
   <meta charset="UTF-8">
-  <title>OWL 0.12.0 Benchmark</title>
+  <title>OWL v1.0.0-beta1 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>

tools/benchmarks/owl-1.0.0-beta1/templates.xml

@@ -12,11 +12,11 @@
         </div>
         <div class="flags">
             <div>
-                <input type="checkbox" id="multipleflag" t-on-change="toggleMultiple" t-att-checked="state.multipleFlag"/>
+                <input type="checkbox" id="multipleflag" t-model="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"/>
+                <input type="checkbox" id="clearFlag" t-model="state.clearAfterFlag" />
                 <label for="clearFlag">Clear after</label>
             </div>
         </div>

tools/debug.js

@@ -0,0 +1,149 @@
+/**
+ * Debug Script
+ *
+ * This code is intended to be evaluated in an environment where owl is available,
+ * to log lot of helpful information on how Owl components behave.
+ */
+
+ function debugOwl(owl, options) {
+  let prefix = "[OWL_DEBUG]";
+  let current;
+  Object.defineProperty(owl.Component, "current", {
+    get() {
+      return current;
+    },
+    set(comp) {
+      current = comp;
+      const name = comp.constructor.name;
+      if (options.componentBlackList && options.componentBlackList.test(name)) {
+        return;
+      }
+      if (options.componentWhiteList && !options.componentWhiteList.test(name)) {
+        return;
+      }
+      let __owl__;
+      Object.defineProperty(current, "__owl__", {
+        get() {
+          return __owl__;
+        },
+        set(val) {
+          __owl__ = val;
+          debugComponent(comp, name, __owl__.id);
+        }
+      });
+    }
+  });
+
+  function toStr(obj) {
+    let str = JSON.stringify(obj || {});
+    if (str.length > 200) {
+      str = str.slice(0, 200) + "...";
+    }
+    return str;
+  }
+
+  function debugComponent(component, name, id) {
+    let fullName = `${name}<id=${id}>`;
+    let log = str => console.log(`${prefix} ${fullName} ${str}`);
+    let shouldDebug = method => {
+      if (options.methodBlackList && options.methodBlackList.includes(method)) {
+        return false;
+      }
+      if (options.methodWhiteList && !options.methodWhiteList.includes(method)) {
+        return false;
+      }
+      return true;
+    };
+    if (shouldDebug("constructor")) {
+      log(`constructor, props=${toStr(component.props)}`);
+    }
+    if (shouldDebug("willStart")) {
+      owl.hooks.onWillStart(() => {
+        log(`willStart`);
+      });
+    }
+    if (shouldDebug("mounted")) {
+      owl.hooks.onMounted(() => {
+        log(`mounted`);
+      });
+    }
+    if (shouldDebug("willUpdateProps")) {
+      owl.hooks.onWillUpdateProps(nextProps => {
+        log(`willUpdateProps, nextprops=${toStr(nextProps)}`);
+      });
+    }
+    if (shouldDebug("willPatch")) {
+      owl.hooks.onWillPatch(() => {
+        log(`willPatch`);
+      });
+    }
+    if (shouldDebug("patched")) {
+      owl.hooks.onPatched(() => {
+        log(`patched`);
+      });
+    }
+    if (shouldDebug("willUnmount")) {
+      owl.hooks.onWillUnmount(() => {
+        log(`willUnmount`);
+      });
+    }
+    const __render = component.__render.bind(component);
+    component.__render = function(...args) {
+      log(`rendering template`);
+      __render(...args);
+    };
+    const render = component.render.bind(component);
+    component.render = function(...args) {
+      const __owl__ = component.__owl__;
+      let msg = `render`;
+      if (!__owl__.isMounted && !__owl__.currentFiber) {
+        msg += ` (warning: component is not mounted, this render has no effect)`;
+      }
+      log(msg);
+      return render(...args);
+    };
+    const mount = component.mount.bind(component);
+    component.mount = function(...args) {
+      log(`mount`);
+      return mount(...args);
+    };
+  }
+
+  if (options.logScheduler) {
+    let start = owl.Component.scheduler.start;
+    let stop = owl.Component.scheduler.stop;
+    owl.Component.scheduler.start = function () {
+      if (!this.isRunning) {
+        console.log(`${prefix} scheduler: start running tasks queue`);
+      }
+      start.call(this);
+    };
+    owl.Component.scheduler.stop = function () {
+      if (this.isRunning) {
+        console.log(`${prefix} scheduler: stop running tasks queue`);
+      }
+      stop.call(this);
+    };
+  }
+  if (options.logStore) {
+    let dispatch = owl.Store.prototype.dispatch;
+    owl.Store.prototype.dispatch = function(action, ...payload) {
+      console.log(`${prefix} store: action '${action}' dispatched. Payload: '${toStr(payload)}'`);
+      return dispatch.call(this, action, ...payload);
+    };
+  }
+}
+
+
+// This debug function can then be used like this:
+//
+// debugOwl(owl, {
+//   componentBlackList: /App/,  // regexp
+//   componentWhiteList: /SomeComponent/, // regexp
+//   methodBlackList: ["mounted"], // list of method names
+//   methodWhiteList: ["willStart"], // list of method names
+//   logScheduler: true, // display/mute scheduler logs
+//   logStore: true // display/mute store logs
+// });
+
+module.exports.debugOwl = debugOwl;

tools/index.html

@@ -28,19 +28,15 @@
         <div class="benchmarks">
             <ul>
                 <li><a href="benchmarks/owl-0.7.0">OWL 0.7.0</a></li>
-                <li><a href="benchmarks/owl-0.8.0">OWL 0.8.0</a></li>
                 <li><a href="benchmarks/owl-0.9.0">OWL 0.9.0</a></li>
-                <li><a href="benchmarks/owl-0.10.0">OWL 0.10.0</a></li>
                 <li><a href="benchmarks/owl-0.11.0">OWL 0.11.0</a></li>
-                <li><a href="benchmarks/owl-0.12.0">OWL 0.12.0</a></li>
                 <li><a href="benchmarks/owl-0.13.0">OWL 0.13.0</a></li>
-                <li><a href="benchmarks/owl-0.14.0">OWL 0.14.0</a></li>
                 <li><a href="benchmarks/owl-0.15.0">OWL 0.15.0</a></li>
-                <li><a href="benchmarks/owl-0.16.0">OWL 0.16.0</a></li>
                 <li><a href="benchmarks/owl-0.17.0">OWL 0.17.0</a></li>
                 <li><a href="benchmarks/owl-0.18.0">OWL 0.18.0</a></li>
                 <li><a href="benchmarks/owl-0.21.0">OWL 0.21.0</a></li>
                 <li><a href="benchmarks/owl-0.24.0">OWL 0.24.0</a></li>
+                <li><a href="benchmarks/owl-1.0.0-beta1">OWL 1.0.0-beta1</a></li>
                 <li><a href="benchmarks/owl-master">OWL Master</a></li>
             </ul>
             <ul>

tools/playground/app.js

@@ -120,20 +120,34 @@ async function makeApp(js, css, xml) {
     .join("\n");
 
   const JS = `
-async function loadTemplates() {
-  try {
-    return owl.utils.loadFile('app.xml');
-  } catch(e) {
-    console.error(\`This app requires a static server.  If you have python installed, try 'python app.py'\`);
-  }
-}
-
-function start([TEMPLATES]) {
-  // Application code
+/**
+ * This is the javascript code defined in the playground.
+ * In a larger application, this code should probably be moved in different
+ * sub files.
+ */
+function app() {
 ${processedJS}
 }
 
-Promise.all([loadTemplates(), owl.utils.whenReady()]).then(start);
+/**
+ * Initialization code
+ * This code load templates, and make sure everything is properly connected.
+ */
+async function start() {
+  let templates;
+  try {
+    templates = await owl.utils.loadFile('app.xml');
+  } catch(e) {
+    console.error(\`This app requires a static server.  If you have python installed, try 'python app.py'\`);
+    return;
+  }
+  const env = { qweb: new owl.QWeb({templates})};
+  owl.Component.env = env;
+  await owl.utils.whenReady();
+  app();
+}
+
+start();
 `;
 
   zip.file("app.js", JS);

tools/playground/samples.js

@@ -2,7 +2,10 @@ const COMPONENTS = `// In this example, we show how components can be defined an
 const { Component, useState } = owl;
 
 class Greeter extends Component {
-    state = useState({ word: 'Hello' });
+    constructor() {
+        super(...arguments);
+        this.state = useState({ word: 'Hello' });
+    }
 
     toggle() {
         this.state.word = this.state.word === 'Hi' ? 'Hello' : 'Hi';
@@ -11,7 +14,10 @@ class Greeter extends Component {
 
 // Main root component
 class App extends Component {
-    state = useState({ name: 'World'});
+    constructor() {
+        super(...arguments);
+        this.state = useState({ name: 'World'});
+    }
 }
 App.components = { Greeter };
 
@@ -47,7 +53,10 @@ const ANIMATION = `// The goal of this component is to see how the t-transition
 const { Component, useState } = owl;
 
 class Counter extends Component {
-    state = useState({ value: 0 });
+    constructor() {
+        super(...arguments);
+        this.state = useState({ value: 0 });
+    }
 
     increment() {
         this.state.value++;
@@ -55,7 +64,10 @@ class Counter extends Component {
 }
 
 class App extends Component {
-    state = useState({ flag: false, componentFlag: false, numbers: [] });
+    constructor() {
+        super(...arguments);
+        this.state = useState({ flag: false, componentFlag: false, numbers: [] });
+    }
 
     toggle(key) {
         this.state[key] = !this.state[key];
@@ -213,7 +225,10 @@ class DemoComponent extends Component {
 }
 
 class App extends Component {
-    state = useState({ n: 0, flag: true });
+    constructor() {
+        super(...arguments);
+        this.state = useState({ n: 0, flag: true });
+    }
 
     increment() {
         this.state.n++;
@@ -282,11 +297,14 @@ function useMouse() {
 
 // Main root component
 class App extends owl.Component {
-    // simple state hook (reactive object)
-    counter = useState({ value: 0 });
+    constructor() {
+        super(...arguments);
+        // simple state hook (reactive object)
+        this.counter = useState({ value: 0 });
 
-    // this hooks is bound to the 'mouse' property.
-    mouse = useMouse();
+        // this hooks is bound to the 'mouse' property.
+        this.mouse = useMouse();
+    }
 
     increment() {
         this.counter.value++;
@@ -318,7 +336,10 @@ const { Component, Context } = owl;
 const { useContext } = owl.hooks;
 
 class ToolbarButton extends Component {
-    theme = useContext(this.env.themeContext);
+    constructor() {
+        super(...arguments);
+        this.theme = useContext(this.env.themeContext);
+    }
 
     get style () {
         const theme = this.theme;
@@ -451,12 +472,11 @@ const actions = {
 // TodoItem
 //------------------------------------------------------------------------------
 class TodoItem extends Component {
-    state = useState({ isEditing: false });
-    dispatch = useDispatch();
-
-    constructor(...args) {
-        super(...args);
+    constructor() {
+        super(...arguments);
         useAutofocus("input");
+        this.state = useState({ isEditing: false });
+        this.dispatch = useDispatch();
     }
 
     handleKeyup(ev) {
@@ -483,9 +503,12 @@ class TodoItem extends Component {
 // TodoApp
 //------------------------------------------------------------------------------
 class TodoApp extends Component {
-    state = useState({ filter: "all" });
-    todos = useStore(state => state.todos);
-    dispatch = useDispatch();
+    constructor() {
+        super(...arguments);
+        this.state = useState({ filter: "all" });
+        this.todos = useStore(state => state.todos);
+        this.dispatch = useDispatch();
+    }
 
     get visibleTodos() {
         switch (this.state.filter) {
@@ -1008,7 +1031,10 @@ class FormView extends owl.Component {}
 FormView.components = { AdvancedComponent };
 
 class Chatter extends owl.Component {
-    messages = Array.from(Array(100).keys());
+    constructor() {
+        super(...arguments);
+        this.messages = Array.from(Array(100).keys());
+    }
 }
 
 class App extends owl.Component {}
@@ -1150,7 +1176,10 @@ const SLOTS = `// We show here how slots can be used to create generic component
 const { Component, useState } = owl;
 
 class Card extends Component {
-    state = useState({ showContent: true });
+    constructor() {
+        super(...arguments);
+        this.state = useState({ showContent: true });
+    }
 
     toggleDisplay() {
         this.state.showContent = !this.state.showContent;
@@ -1158,7 +1187,10 @@ class Card extends Component {
 }
 
 class Counter extends Component {
-    state = useState({val: 1});
+    constructor() {
+        super(...arguments);
+        this.state = useState({val: 1});
+    }
 
     inc() {
         this.state.val++;
@@ -1167,7 +1199,10 @@ class Counter extends Component {
 
 // Main root component
 class App extends Component {
-    state = useState({a: 1, b: 3});
+    constructor() {
+        super(...arguments);
+        this.state = useState({a: 1, b: 3});
+    }
 
     inc(key, delta) {
         this.state[key] += delta;
@@ -1277,7 +1312,10 @@ class SlowComponent extends Component {
 class NotificationList extends Component {}
 
 class App extends Component {
-    state = useState({ value: 0, notifs: [] });
+    constructor() {
+        super(...arguments);
+        this.state = useState({ value: 0, notifs: [] });
+    }
 
     increment() {
         this.state.value++;
@@ -1350,13 +1388,16 @@ const FORM = `// This example illustrate how the t-model directive can be used t
 const { Component, useState } = owl;
 
 class Form extends Component {
-    state = useState({
-        text: "",
-        othertext: "",
-        number: 11,
-        color: "",
-        bool: false
-    });
+    constructor() {
+        super(...arguments);
+        this.state = useState({
+            text: "",
+            othertext: "",
+            number: 11,
+            color: "",
+            bool: false
+        });
+    }
 }
 
 // Application setup
@@ -1403,6 +1444,111 @@ const FORM_XML = `<templates>
 </templates>
 `;
 
+const PORTAL_COMPONENTS = `
+// This shows the expected use case of Portal
+// which is to implement something similar
+// to bootstrap modal
+const { Component, useState } = owl;
+const { Portal } = owl.misc;
+
+class Modal extends Component {}
+Modal.components = { Portal };
+
+class Dialog extends Component {}
+Dialog.components = { Modal };
+
+class Interstellar extends Component {}
+
+// Main root component
+class App extends Component {
+    state = useState({
+        name: 'Portal used for Dialog (Modal)',
+        dialog: false,
+        text: 'Hello !',
+    });
+}
+App.components = { Dialog , Interstellar };
+
+// Application setup
+const app = new App();
+app.mount(document.body);
+`;
+
+const PORTAL_XML = `
+<templates>
+  <t t-name="Modal">
+    <Portal target="'body'">
+        <div class="owl-modal-supercontainer">
+          <div class="owl-modal-backdrop"></div>
+          <div class="owl-modal-container">
+            <t t-slot="default" />
+          </div>
+        </div>
+    </Portal>
+  </t>
+
+  <t t-name="Dialog">
+    <Modal>
+      <div class="owl-dialog-body">
+        <t t-slot="default" />
+      </div>
+    </Modal>
+  </t>
+
+  <div t-name="Interstellar" class="owl-interstellar">
+    <h4>This is a subComponent</h4>
+    <p>The events it triggers will go through the Portal and be teleported
+    on the other side of the wormhole it has created</p>
+    <button t-on-click="trigger('collapse-all')">Close the wormhole</button>
+  </div>
+
+  <div t-name="App" t-on-collapse-all="state.dialog=false">
+    <div t-esc="state.name"/>
+    <button t-on-click="state.dialog = true">Open Dialog</button>
+    <Dialog t-if="state.dialog">
+      <div t-esc="state.text"/>
+      <Interstellar />
+    </Dialog>
+  </div>
+</templates>
+`;
+
+const PORTAL_CSS = `
+.owl-modal-supercontainer {
+  position: static;
+}
+.owl-modal-backdrop {
+    position: fixed;
+    top: 0;
+    left:0;
+    background-color: #000000;
+    opacity: 0.5;
+    width: 100vw;
+    height: 100vh;
+    z-index: 1000;
+}
+.owl-modal-container {
+    opacity:1;
+    z-index: 1050;
+    position: fixed;
+    top: 0;
+    left:0;
+    width: 100%;
+    height: 100%;
+}
+.owl-dialog-body {
+    max-width: 500px;
+    margin: 0 auto;
+    position: relative;
+    text-align: center;
+    padding: 2rem;
+    background-color: #FFFFFF;
+    max-height: 100%;
+}
+.owl-interstellar {
+    border: groove;
+}`
+
 const WMS = `// This example is slightly more complex than usual. We demonstrate
 // here a way to manage sub windows in Owl, declaratively. This is still just a
 // demonstration. Managing windows can be as complex as we want.  For example,
@@ -1419,7 +1565,10 @@ const { useRef } = owl.hooks;
 class HelloWorld extends Component {}
 
 class Counter extends Component {
-  state = useState({ value: 0 });
+  constructor() {
+    super(...arguments);
+    this.state = useState({ value: 0 });
+  }
 
   inc() {
     this.state.value++;
@@ -1470,11 +1619,14 @@ class Window extends Component {
 }
 
 class WindowManager extends Component {
-  windows = [];
-  nextId = 1;
-  currentZindex = 1;
-  nextLeft = 0;
-  nextTop = 0;
+  constructor() {
+    super(...arguments);
+    this.windows = [];
+    this.nextId = 1;
+    this.currentZindex = 1;
+    this.nextLeft = 0;
+    this.nextTop = 0;
+  }
 
   addWindow(name) {
     const info = this.env.windows.find(w => w.name === name);
@@ -1518,7 +1670,10 @@ class WindowManager extends Component {
 WindowManager.components = { Window };
 
 class App extends Component {
-  wmRef = useRef("wm");
+  constructor() {
+    super(...arguments);
+    this.wmRef = useRef("wm");
+  }
 
   addWindow(name) {
     this.wmRef.comp.addWindow(name);
@@ -1552,7 +1707,7 @@ const WMS_XML = `<templates>
   <div t-name="Window" class="window" t-att-style="style" t-on-click="updateZIndex">
     <div class="header">
       <span t-on-mousedown="startDragAndDrop"><t t-esc="props.info.title"/></span>
-      <span class="close" t-on-click="close">×</span>
+      <span class="close" t-on-click.stop="close">×</span>
     </div>
     <t t-slot="default"/>
   </div>
@@ -1720,5 +1875,11 @@ export const SAMPLES = [
     code: ASYNC_COMPONENTS,
     xml: ASYNC_COMPONENTS_XML,
     css: ASYNC_COMPONENTS_CSS
-  }
+  },
+  {
+    description: "Portal (Dialog)",
+    code: PORTAL_COMPONENTS,
+    xml: PORTAL_XML,
+    css: PORTAL_CSS,
+  },
 ];