[REL] v2.0.0-beta-9

# v2.0.0-beta-9 Fixes - event: no crash when using t-on + modifier on slots/components - component: fix props comparison code - component: fix wrong behaviour when using t-on on t-component - component: props values are own property of props object - t-out: allow expressions evaluating as number - compiler: add support for #{...} in string interpolation Improvements - slots: add support for t-props on slots props - tooling: add another d.ts file
[IMP] tooling: add another d.ts file
2025-10-06 19:59:41 +07:00 · 2022-06-09 14:32:13 +02:00 · 2022-06-09 14:21:34 +02:00 · 2022-06-08 10:54:30 +02:00 · 2022-06-07 13:23:29 +02:00 · 2022-06-07 09:30:45 +02:00
164 changed files with 12255 additions and 4504 deletions
@@ -5,7 +5,7 @@ name: Node.js CI

 on:
  pull_request:
-    branches: [ master, owl-next ]
+    branches: [ master ]

 jobs:
  build:
@@ -30,19 +30,32 @@ All changes are documented here in no particular order.
 - breaking: `catchError` method is replaced by `onError` hook ([details](#36-catcherror-method-is-replaced-by-onerror-hook))
 - breaking: Support for inline css (`css` tag and static `style`) has been removed ([details](#37-support-for-inline-css-css-tag-and-static-style-has-been-removed))
 - new: prop validation system can now describe that additional props are allowed (with `*`) ([doc](doc/reference/props.md#props-validation))
+- breaking: prop validation system does not allow default prop on a mandatory (not optional) prop ([doc](doc/reference/props.md#props-validation))
+- breaking: rendering a component does not necessarily render child components ([details](#40-rendering-a-component-does-not-necessarily-render-child-components))
+


 **Templates**

 - breaking: `t-foreach` should always have a corresponding `t-key` ([details](#20-t-foreach-should-always-have-a-corresponding-t-key))
 - breaking: `t-ref` does not work on components ([details](#29-t-ref-does-not-work-on-component))
- breaking: `t-on` does not accept expressions, only functions ([details](#30-t-on-does-not-accept-expressions-only-functions))
 - breaking: `t-raw` directive has been removed (replaced by `t-out`) ([details](#38-t-raw-directive-has-been-removed-replaced-by-t-out))
 - new: add support for synthetic events ([doc](doc/reference/event_handling.md#synthetic-events))
 - breaking: style/class on components are now regular props ([details](#10-styleclass-on-components-are-now-regular-props))
 - new: components can use the `.bind` suffix to bind function props ([doc](doc/reference/props.md#binding-function-props))
- breaking: `t-on` does not work on components any more ([details](#12-t-on-does-not-work-on-components-any-more))
+- breaking: `t-on` does not accept expressions, only functions ([details](#30-t-on-does-not-accept-expressions-only-functions))
+- new: an error is thrown if an handler defined in a `t-on-` directive is not a function (failed silently previously in some cases)
 - breaking: `t-component` no longer accepts strings ([details](#17-t-component-no-longer-accepts-strings))
+- new: the `this` variable in template expressions is now bound to the component
+
+
+**Reactivity**
+
+- finer grained reactivity: owl 2 tracks change per key/component
+- finer grained reactivity: sub components can reobserve state ([doc](doc/reference/reactivity.md))
+- new: `reactive` function: create reactive state (without being linked to a component) ([doc](doc/reference/reactivity.md#reactive))
+- new: `markRaw` function: mark an object or array so that it is ignored by the reactivity system ([doc](doc/reference/reactivity.md#markraw))
+- new: `toRaw` function: given a reactive objet, return the raw (non reactive) underlying object ([doc](doc/reference/reactivity.md#toraw))


 **Slots**
@@ -66,13 +79,12 @@ All changes are documented here in no particular order.

 - improved performance
 - much simpler code 
- finer grained reactivity: owl 2 tracks change per key/component
- finer grained reactivity: sub components can reobserve state
 - new App class to encapsulate a root Owl component (with the config for that application) ([doc](doc/reference/app.md))
- new `Memo` component
 - new `useEffect` hook ([doc](doc/reference/hooks.md#useeffect))
 - breaking: `Context` is removed ([details](#15-context-is-removed))
 - breaking: `env` is now totally empty ([details](#16-env-is-now-totally-empty))
+- breaking: `env` is now frozen ([details](#28-env-is-now-frozen))
+- new hook: `useChildSubEnv` (only applies to child components) ([details](#27-usechildsubenv-only-applies-to-child-components))
 - breaking: most exports are exported at top level ([details](#18-most-exports-are-exported-at-top-level))
 - breaking: properties are no longer set as attributes ([details](#19-properties-are-no-longer-set-as-attributes))
 - breaking: `EventBus` api changed: it is now an `EventTarget` ([details](#21-eventbus-api-changed-it-is-now-an-eventtarget))
@@ -81,8 +93,6 @@ All changes are documented here in no particular order.
 - breaking: transition system is removed ([details](#24-transition-system-is-removed))
 - breaking: no more global components or templates ([details](#25-no-more-global-components-or-templates))
 - breaking: `AsyncRoot` utility component is removed ([details](#26-asyncroot-utility-component-is-removed))
- breaking: `useSubEnv` only applies to child components ([details](#27-usesubenv-only-applies-to-child-components))
- breaking: `env` is now frozen ([details](#28-env-is-now-frozen))
 - breaking: `renderToString` function on qweb has been removed ([details](#32-rendertostring-on-qweb-has-been-removed))
 - breaking: `debounce` utility function has been removed ([details](#34-debounce-utility-function-has-been-removed))
 - breaking: `browser` object has been removed ([details](#39-browser-object-has-been-removed))
@@ -237,35 +247,12 @@ Rationale: `shouldUpdate` is a dangerous method to use, that may cause a lot of
 issues. Vue does not have such a mechanism (see https://github.com/vuejs/vue/issues/4255),
 because the reactivity system in Vue is smart enough to only rerender the minimal
 subset of components that is subscribed to a piece of state. Now, Owl 2 features
-a much more powerful reactivity system.
+a much more powerful reactivity system, so the same rationale applies: in a way,
+it's like each Owl 2 component has a `shouldUpdate` method that precisely tracks
+every value used by the component.

-Migration code: remove the `shouldUpdate` methods. Then, maybe the following
-ideas may help:
-
- try to organize the state/architecture to minimize the number of state updates
- take advantage of the finer reactivity system. For example, if we have a list
-  of items, with a component for each item, we can write this:
-
-  ```js
-  class Item extends Component {
-      setup() {
-          this.item = useState(this.props.item); // and only use this, not props.item
-      }
-  }
-  ```
-  Doing so will make it that each `Item` component will register itself as an
-  observer of its own item, and will be the only component being rerendered when
-  its item object is updated.
- use the `Memo` component to wrap some piece of template. `Memo` memoize its
-  content, and only update itself if its props are different (shallow comparison):
-  
-  ```xml
-    <Memo a="state.a" b="state.b"> 
-        <t t-esc="state.a"/>
-        <t t-esc="state.b"/>
-        <t t-esc="state.c"/>
-    </Memo>
-  ```
+Migration code: remove the `shouldUpdate` methods, and it should work as well
+as before.

 ### 9. component.el is removed

@@ -325,41 +312,6 @@ Documentation:
 - [Mounting a component](doc/reference/app.md#mount-helper)


-### 12. `t-on` does not work on components any more
-
-In owl 1, it was possible to bind an event listener on a component tag in a
-template:
-
-```xml
-<SomeComponent t-on-some-event="doSomething"/>
-```
-
-This does not work any more.
-
-Rationale: with the support of fragments, there is no longer a canonical html
-element that we can refer. So, this makes it difficult to implement correctly
-and efficiently. Also, we noticed in practice that the event system was an issue
-in some cases, when components need to communicate before they are mounted. In
-those cases, the better solution is to directly use a callback.  Also, another
-conceptual issue with this is that it kind of breaks the component encapsulation.
-The child component kind of leak its own implementation to the outside world.
-
-Migration: a quick fix that may work in some cases is to simply bind the event
-handler on a parent htmlelement. A better way to do it, if possible, is to change
-the component API to accept explicitely a callback as props. 
-
-```xml
-<SomeComponent onSomeEvent="doSomething"/>
-<!-- or alternatively: -->
-<SomeComponent onSomeEvent.bind="doSomething"/>
-```
-
-Note that one of the example above uses the `.bind` suffix, to bind the function
-prop to the component.  Most of the time, binding the function is necessary, and
-using the `.bind` suffix is very helpful in that case.
-
-Documentation: [Binding function props](doc/reference/props.md#binding-function-props)
-
 ### 13. Portal does no longer transfer DOM events

 In Owl 1, a Portal component would listen to events emitted on its portalled
@@ -565,15 +517,12 @@ either a fallback when the data is not ready, or the actual component with data
 as props.  If there is no escape, and `AsyncRoot` is needed, please reach out to
 us so we can study this usecase.

-### 27. `useSubEnv` only applies to child components
+### 27. `useChildSubEnv` (only applies to child components)

-In Owl 1, a call to `useSubEnv` would define a new environment for the children
-AND the component. It now only defines an environment for the children.
-
-Rationale: This was a subtle cause for bugs: some code had to be rrun
-before the call to `useSubEnv`, otherwise it could interfere with the sub environment.
-
-Documentation: [Hooks](doc/reference/hooks.md#usesubenv)
+In Owl, a call to `useSubEnv` would define a new environment for the children
+AND the component. It is very useful, but in some cases, one only need to update
+the children component environment. This can now be done with a new hook:
+[`useChildSubEnv`](doc/reference/hooks.md#usesubenv-and-usechildsubenv)

 ### 28. `env` is now frozen

@@ -659,10 +608,14 @@ Also, this can easily be done in userspace, by mounting a component in a div.  F
 export async function renderToString(template, context) {
  class C extends Component {
    static template = template;
+    setup () {
+        Object.assign(this, context);
+    }
  }
  const div = document.createElement('div');
  document.body.appendChild(div);
-  const component = await mount(C, div);
+  const app = new App(C);
+  await app.mount(div);
  const result = div.innerHTML;
  app.destroy();
  div.remove();
@@ -670,6 +623,30 @@ export async function renderToString(template, context) {
 }
 ```

+The function above works for most cases, but is asynchronous.  An alternative
+function could look like this:
+
+```js
+const { App, blockDom } = owl;
+const app = new App(Component); // act as a template repository
+
+function renderToString(template, context = {}) {
+  app.addTemplate(template, template, { allowDuplicate: true });
+  const templateFn = app.getTemplate(template);
+  const bdom = templateFn(context, {});
+  const div = document.createElement('div')
+  blockDom.mount(bdom, div);
+  return div.innerHTML;
+}
+```
+
+This is a synchronous function, so it will not work with components, but it should
+be useful for most simple templates.
+
+Also note that these two examples do not translate their templates. To do that,
+they need to be modified to pass the proper translate function to the `App`
+configuration.
+
 ### 33. Portal are now defined with `t-portal`

 Before Owl 2, one could use the `Portal` component by importing it and using it.
@@ -762,4 +739,28 @@ Rationale: the `browser` object caused more trouble than it was worth. Also, it
 seems like this should be done in user space, not at the framework level.  

 Migration: code should just be adapted to either use another browser object,
-or to use native browser function (and then, just mock them directly).
+or to use native browser function (and then, just mock them directly).
+
+## 40. Rendering a component does not necessarily render child components
+
+Before, if one had the following component tree:
+
+```mermaid
+  graph TD;
+      A-->B;
+      A-->C;
+```
+
+when `A` would render, it would also render `B` and `C`. Now, in Owl 2, it will 
+(shallow) compare the before and after props, and `B` or `C` will only be rerendered
+if their props have changed.
+
+Now, the question is what happens if the props have changed, but in a deeper way?
+In that case, Owl will know, because each props are now reactive. So, if some
+inner value read by `B` was changed, then only `B` will be updated.
+
+Rationale: This was just not possible in Owl 1, but it now possible. This is
+due to the rewriteof the underlying rendering engine and the reactivity
+system. The goal is to have a big performance boost in large screen with many
+components: now Owl only rerender what is strictly useful.
+
@@ -82,6 +82,7 @@ Are you new to Owl? This is the place to start!
 - [Component](doc/reference/component.md)
 - [Component Lifecycle](doc/reference/component.md#lifecycle)
 - [Concurrency Model](doc/reference/concurrency_model.md)
+- [Dev mode](doc/reference/app.md#dev-mode)
 - [Dynamic sub components](doc/reference/component.md#dynamic-sub-components)
 - [Environment](doc/reference/environment.md)
 - [Error Handling](doc/reference/error_handling.md)
@@ -92,6 +93,7 @@ Are you new to Owl? This is the place to start!
 - [Loading Templates](doc/reference/app.md#loading-templates)
 - [Mounting a component](doc/reference/app.md#mount-helper)
 - [Portal](doc/reference/portal.md)
+- [Precompiling templates](doc/reference/precompiling_templates.md)
 - [Props](doc/reference/props.md)
 - [Props Validation](doc/reference/props.md#props-validation)
 - [Reactivity](doc/reference/reactivity.md)
@@ -110,6 +112,7 @@ Are you new to Owl? This is the place to start!
 - [Comparison with React/Vue](doc/miscellaneous/comparison.md)
 - [Why did Odoo build Owl?](doc/miscellaneous/why_owl.md)
 - [Changelog (from owl 1.x to 2.x)](CHANGELOG.md)
+- [Notes on compiled templates](doc/miscellaneous/compiled_template.md)

 ## Installing Owl

@@ -121,5 +124,5 @@ npm install @odoo/owl

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

- [owl-1.4.7](https://github.com/odoo/owl/releases/tag/v1.4.7)
+- [owl-1.4.10](https://github.com/odoo/owl/releases/tag/v1.4.10)

@@ -240,7 +240,7 @@ class Task extends Component {
  static template = xml /* xml */`
    <div class="task" t-att-class="props.task.isCompleted ? 'done' : ''">
      <input type="checkbox" t-att-checked="props.task.isCompleted"/>
-      <span><t t-esc="props.task.title"/></span>
+      <span><t t-esc="props.task.text"/></span>
    </div>`;
  static props = ["task"];
 }
@@ -743,7 +743,7 @@ the user experience.
 ```xml
 <input type="checkbox" t-att-checked="props.task.isCompleted"
    t-att-id="props.task.id"
-    t-on-click="dispatch('toggleTask', props.task.id)"/>
+    t-on-click="() => store.toggleTask(props.task)"/>
 <label t-att-for="props.task.id"><t t-esc="props.task.text"/></label>
 ```

@@ -0,0 +1,98 @@
+# 🦉 Notes On Owl Compiled Templates 🦉
+
+This page will explain what an Owl compiled template look like. This is a
+technical document intended for developers interested in understanding how Owl
+works internally.
+
+Broadly speaking, Owl compiles templates into a javascript function (a closure)
+that returns a function (the "render" function). The point of the closure is to
+have a place to store all values specific to the template (in particular, "blocks").
+Once a template is compiled, its closure function is called once to get the
+render function, and from then on, only the render function is used.
+
+The render function takes some context (and some additional information) and
+return a virtual dom representation of the rendered template, as a block tree.
+A block tree is a very light weight representation that only contains the dynamic
+part of the template, and its structure. It is actually independant of the
+static part of the templates (which are contained in the blocks captured by the
+closure). This means that the work performed at render time is only to collect
+dynamic data, and to describe the block structure of the result.
+
+It looks like this, in pseudo code:
+
+```js
+function closure(bdom, helpers) {
+    // here is some place to put stuff specific to the template, such as
+    // blocks
+    ...
+
+    return function render(context, node, key) {
+        // only build here all dynamic parts of the template
+        // build a block tree
+        return tree;
+    }
+}
+```
+
+Now, let us see an example. Consider the following template:
+
+```xml
+<div class="some-class">
+    <div class="blabla">
+        <span><t t-esc="state.value"/></span>
+    </div>
+    <t t-if="state.info">
+        <p class="info" t-att-class="someAttribute">
+            <t t-esc="state.info"/>
+        </p>
+    </t>
+    <SomeComponent value="value"/>
+</div>
+```
+
+If you look carefully, there are 5 dynamic things:
+
+- a text value (the first `t-esc`),
+- a sub block (the `t-if`),
+- a dynamic attribute (the `t-att-class` attribute),
+- another text value (the second `t-esc`),
+- and finally, a sub component
+
+Here is the compiled code for this template:
+
+```js
+function closure(bdom, helpers) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+
+  let block1 = createBlock(
+    `<div class="some-class"><div class="blabla"><span><block-text-0/></span></div><block-child-0/><block-child-1/></div>`
+  );
+  let block2 = createBlock(`<p class="info" block-attribute-0="class"><block-text-1/></p>`);
+
+  return function render(ctx, node, key = "") {
+    let b2, b3;
+    let txt1 = ctx["state"].value;
+    if (ctx["state"].info) {
+      let attr1 = ctx["someAttribute"];
+      let txt2 = ctx["state"].info;
+      b2 = block2([attr1, txt2]);
+    }
+    b3 = component(`SomeComponent`, { value: ctx["value"] }, key + `__1`, node, ctx);
+    return block1([txt1], [b2, b3]);
+  };
+}
+```
+
+The values captured in the closure capture the static part of the template: we
+define here two blocks (which contains a template node, that can be deep cloned
+whenever a block is mounted). Then the render function only describes the block
+tree structure of the result, depending on the context. This means that we
+minimize the amount of work done at render time.
+
+Then, when we want to patch the dom, Owl will uses the `patch` function from
+blockdom, which then will diff the block tree, and deep clone new blocks whenever
+a new block is inserted, keep track of dynamic parts of each block, and update
+them accordingly.
+
+With this design, the cost of rendering a template is proportional to the number
+of dynamic values, and not to the size of the template.
@@ -7,9 +7,14 @@ Main entities:
 - [`App`](reference/app.md): represent an Owl application (mainly a root component,a set of templates, and a config)
 - [`Component`](reference/component.md): the main class to define a concrete Owl component
 - [`mount`](reference/app.md#mount-helper): main entry point for most application: mount a component to a target
+- [`xml`](reference/templates.md#inline-templates): helper to define an inline template
+
+Reactivity
+
 - [`useState`](reference/reactivity.md#usestate): create a reactive object (hook, linked to a specific component)
 - [`reactive`](reference/reactivity.md#reactive): create a reactive object (not linked to any component)
- [`xml`](reference/templates.md#inline-templates): helper to define an inline template
+- [`markRaw`](reference/reactivity.md#markraw): mark an object or array so that it is ignored by the reactivity system
+- [`toRaw`](reference/reactivity.md#toraw): given a reactive objet, return the raw (non reactive) underlying object

 Lifecycle hooks:

@@ -31,7 +36,8 @@ Other hooks:
 - [`useEnv`](reference/hooks.md#useenv): return a reference to the current env
 - [`useExternalListener`](reference/hooks.md#useexternallistener): add a listener outside of a component DOM
 - [`useRef`](reference/hooks.md#useref): get an object representing a reference (`t-ref`)
- [`useSubEnv`](reference/hooks.md#usesubenv): extend the current env with additional information for child components
+- [`useChildSubEnv`](reference/hooks.md#usesubenv-and-usechildsubenv): extend the current env with additional information (for child components)
+- [`useSubEnv`](reference/hooks.md#usesubenv-and-usechildsubenv): extend the current env with additional information (for current component and child components)

 Utility/helpers:

@@ -39,4 +45,5 @@ Utility/helpers:
 - [`loadFile`](reference/utils.md#loadfile): an helper to load a file from the server
 - [`markup`](reference/templates.md#outputting-data): utility function to define strings that represent html (should not be escaped)
 - [`status`](reference/component.md#status-helper): utility function to get the status of a component (new, mounted or destroyed)
+- [`validate`](reference/utils.md#validate): validates if an object satisfies a specified schema
 - [`whenReady`](reference/utils.md#whenready): utility function to execute code when DOM is ready
@@ -3,6 +3,7 @@
 ## Content

 - [Overview](#overview)
+- [API](#api)
 - [Configuration](#configuration)
 - [`mount` helper](#mount-helper)
 - [Loading templates](#loading-templates)
@@ -26,24 +27,10 @@ The basic workflow is: create an `App` instance configured with the root
 component, the templates, and possibly other settings. Then, we mount that
 instance somewhere in the DOM.

-## Configuration
+## API

 - **`constructor(Root[, config])`**: first argument should be a component class (not
-  an instance), and the optional second argument is a configuration object.
-
-  The `config` object is an object with some of the following keys:
-
-  - **`env (object)`**: if given, this will be the shared `env` given to each component
-  - **`props (object)`**: the props given to the root component
-  - **`dev (boolean, default=false)`**: if `true`, the application is rendered in `dev`
-    mode, which activates some additional checks (in particular, the props validation
-    code is only performed in dev mode)
-  - **`translatableAttributes (string[])`**: a list of additional attributes that should
-    be translated (see [translations](translations.md))
-  - **`translateFn (function)`**: a function that will be called by owl to translate
-    templates (see [translations](translations.md))
-  - **`templates (string | xml document)`**: all the templates that will be used by
-    the components created by the application.
+  an instance), and the optional second argument is a configuration object (see below).

 - **`mount(target, options)`**: first argument is an html element, and the optional
  second argument is an object with mounting options (see below). Mount the app
@@ -58,6 +45,25 @@ instance somewhere in the DOM.

 - **`destroy()`**: destroys the application

+## Configuration
+
+The `config` object is an object with some of the following keys:
+
+- **`env (object)`**: if given, this will be the shared `env` given to each component
+- **`props (object)`**: the props given to the root component
+- **`dev (boolean, default=false)`**: if `true`, the application is rendered in
+  [`dev` mode](#dev-mode);
+- **`test (boolean, default=false)`**: `test` mode is the same as `dev` mode, except
+  that Owl will not log a message to warn that Owl is in `dev` mode.
+- **`translatableAttributes (string[])`**: a list of additional attributes that should
+  be translated (see [translations](translations.md))
+- **`translateFn (function)`**: a function that will be called by owl to translate
+  templates (see [translations](translations.md))
+- **`templates (string | xml document)`**: all the templates that will be used by
+  the components created by the application.
+- **`warnIfNoStaticProps (boolean, default=false)`**: if true, Owl will log a warning
+  whenever it encounters a component that does not provide a [static props description](props.md#props-validation).
+
 ## `mount` helper

 Note that there is a `mount` helper to do that in just a line:
@@ -105,3 +111,13 @@ const { loadFile, mount } = owl;
  mount(Root, document.body, { env });
 })();
 ```
+
+## Dev mode
+
+Dev mode activates some additional checks and developer amenities:
+
+- [Props validation](./props.md#props-validation) is performed
+- [t-foreach](./templates.md#loops) loops check for key unicity
+- Lifecycle hooks are wrapped to report their errors in a more developer-friendly way
+- onWillStart and onWillUpdateProps will emit a warning in the console when they
+  take longer than 3 seconds in an effort to ease debugging the presence of deadlocks
@@ -68,12 +68,17 @@ The `Component` class has a very small API.
  component will go through the following lifecycle methods: `willUpdateProps`,
  `willPatch` and `patched`.

-* **`render()`**: calling this method directly will cause a rerender. Note
+* **`render(deep[=false])`**: calling this method directly will cause a rerender. Note
  that with the reactivity system, this should be rare to have to do it manually.
  Also, the rendering operation is asynchronous, so the DOM will only be updated
  slightly later (at the next animation frame, if no component delays the
  rendering)

+  By default, the render initiated by this method will stop at each child
+  component if their props are (shallow) equal. To force a render to update
+  all child components, one can use the optional `deep` argument. Note that the
+  value of the `deep` argument needs to be a boolean, not a truthy value.
+
 ## Static Properties

 - **`template (string)`**: this is the name of the template that
@@ -1,105 +0,0 @@
-# 🦉 Context 🦉
-
-## Content
-
- [Overview](#overview)
- [Example](#example)
- [Reference](#reference)
-  - [`Context`](#context)
-  - [`useContext`](#usecontext)
-
-## Overview
-
-The `Context` object provides a way to share data between an arbitrary number
-of components. Usually, data is passed from a parent to its children component,
-but when we have to deal with some mostly global information, this can be
-annoying, since each component will need to pass the information to each children,
-even though some or most of them will not use the information.
-
-With a `Context` object, each component can subscribe (with the `useContext` hook)
-to its state, and will be updated whenever the context state is updated.
-
-## Example
-
-Assume that we have an application with various components which needs to render
-differently depending on the size of the device. Here is how we could proceed
-to make sure that the information is properly shared. First, let us create a
-context, and add it to the environment:
-
-```js
-const deviceContext = new Context({ isMobile: true });
-App.env.deviceContext = deviceContext;
-```
-
-If we want to make it completely responsive, we need to update its value whenever
-the size of the screen is updated:
-
-```js
-const isMobile = () => window.innerWidth <= 768;
-window.addEventListener(
-  "resize",
-  owl.utils.debounce(() => {
-    const state = deviceContext.state;
-    if (state.isMobile !== isMobile()) {
-      state.isMobile = !state.isMobile;
-    }
-  }, 15)
-);
-```
-
-Then, each component that want can subscribe and render differently depending on the
-fact that we are in a mobile or desktop mode.
-
-```js
-class SomeComponent extends Component {
-  static template = xml`
-    <div>
-      <t t-if=device.isMobile>
-          some simplified user interface
-      </t>
-      <t t-else="">
-          a more advanced user interface
-      </t>
-    </div>`;
-  device = useContext(this.env.deviceContext);
-}
-```
-
-## Reference
-
-### `Context`
-
-A `Context` object should be created with a state object:
-
-```js
-const someContext = new Context({ some: "key" });
-```
-
-Its state is now available in the `state` key:
-
-```js
-someContext.state.some = "other key";
-```
-
-This is the way some global code (such as the responsive code above) should
-read and update the context state. However, components should not ever read the
-context state directly from the context, they should instead use the `useContext`
-hook to properly register themselves to state changes.
-
-Note that the `Context` hook is different from the React version. For example,
-there is no concept of provider/consumer. So, the `Context` feature does not
-by itself allow the use of a different context state depending on the component
-place in the component tree. However, this functionality can be obtained, if
-necessary, with the use of sub environment.
-
-### `useContext`
-
-The `useContext` hook is the normal way for a component to register themselve
-to context state changes. The `useContext` method returns the context state:
-
-```js
-device = useContext(this.env.deviceContext);
-```
-
-It is a simple observed state (with an owl `Observer`), which contains the shared
-information.
@@ -52,7 +52,7 @@ 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).
+There are two hooks for this situation: [`useSubEnv` and `useChildSubEnv`](hooks.md#usesubenv-and-usechildsubenv).

 ```js
 class SomeComponent extends Component {
@@ -1,25 +0,0 @@
-# 🦉 Event Bus 🦉
-
-It is sometimes useful to use a `Bus` to communicate informations between various
-parts of the code. Owl has a very simple bus class, which manages subscriptions,
-triggering events, and callbacks.
-
-```js
-const bus = new owl.core.EventBus();
-
-bus.on("some-event", null, function (...args) {
-  console.log(...args);
-});
-
-bus.trigger("some-event", 1, 2, 3);
-// [1,2,3] will be logged to the console
-```
-
-Its API is:
-
-| Method                           | Description                       |
-| -------------------------------- | --------------------------------- |
-| `on(eventType, owner, callback)` | add a listener                    |
-| `off(eventType, owner)`          | remove all listeners for an owner |
-| `trigger(eventType, ...args)`    | trigger an event                  |
-| `clear`                          | remove all subscriptions          |
@@ -5,6 +5,7 @@
 - [Event Handling](#event-handling)
 - [Modifiers](#modifiers)
 - [Synthetic Events](#synthetic-events)
+- [On Components](#on-components)

 ## Event Handling

@@ -100,3 +101,19 @@ To enable it, one can just use the `.synthetic` suffix:
    </t>
 </div>
 ```
+
+## On Components
+
+The `t-on` directive also works on a child component:
+
+```xml
+<div>
+    in some template
+    <Child t-on-click="dosomething"/>
+</div>
+```
+
+This will catch all click events on any html element contained in the `Child`
+sub component. Note that if the child component is reduced to one (or more) text
+nodes, then clicking on it will not call the handler, since the event will be
+dispatched by the browser on the parent element (a `div` in this case).
@@ -8,7 +8,7 @@
 - [Other hooks](#other-hooks)
  - [`useState`](#usestate)
  - [`useRef`](#useref)
-  - [`useSubEnv`](#usesubenv)
+  - [`useSubEnv` and `useChildSubEnv`](#usesubenv-and-usechildsubenv)
  - [`useExternalListener`](#useexternallistener)
  - [`useComponent`](#usecomponent)
  - [`useEnv`](#useenv)
@@ -152,14 +152,14 @@ this.ref2 = useRef("component_2");
 References are only guaranteed to be active while the parent component is mounted.
 If this is not the case, accessing `el` or `comp` on it will return `null`.

-### `useSubEnv`
+### `useSubEnv` and `useChildSubEnv`

 The environment is sometimes useful to share some common information between
 all components. But sometimes, we want to _scope_ that knowledge to a subtree.

 For example, if we have a form view component, maybe we would like to make some
 `model` object available to all sub components, but not to the whole application.
-This is where the `useSubEnv` hook may be useful: it lets a component add some
+This is where the `useChildSubEnv` hook may be useful: it lets a component add some
 information to the environment in a way that only its children
 can access it:

@@ -167,15 +167,26 @@ can access it:
 class FormComponent extends Component {
  setup() {
    const model = makeModel();
+    // model will be available on this.env for this component and all children
    useSubEnv({ model });
+    // someKey will be available on this.env for all children
+    useChildSubEnv({ someKey: "value" });
  }
 }
 ```

-The `useSubEnv` takes one argument: an object which contains some key/value that
-will be added to the parent environment. Note that it will extend, not replace
-the parent environment. And of course, the parent environment will not be
-affected.
+The `useSubEnv` and `useChildSubEnv` hooks take one argument: an object which
+contains some key/value that will be added to the current environment. These hooks
+will create a new env object with the new information:
+
+- `useSubEnv` will assign this new `env` to itself and to all children components
+- `useChildSubEnv` will only assign this new `env` to all children components.
+
+As usual in Owl, [environments](environment.md) created with these two hooks are
+frozen, to prevent unwanted modifications.
+
+Note that both these hooks can be called an arbitrary number of times. The `env`
+will then be updated accordingly.

 ### `useExternalListener`

@@ -0,0 +1,30 @@
+# 🦉 Precompiling templates 🦉
+
+Owl is designed to be used by the Odoo javascript framework. Since Odoo handles
+its assets in its own non standard way, it was decided/assumed that Owl would
+compile templates at runtime.
+
+However, in some cases, it is not optimal, or even worse, not possible to do that.
+For example, browser extensions do not allow javascript code to create a new
+function (using the `new Function(...)` syntax).
+
+Therefore, in these cases, it is required to compile templates ahead of time. It
+is possible to do that in Owl, but the tooling is still rough. For now, the
+process is the following:
+
+1. write your templates in xml files (with a `t-name` directive to declare the name
+   of the template)
+2. Compile them in a `templates.js` file
+3. get the `owl.iife.runtime.js` file (which is a owl build without the compiler)
+4. bundle `owl.iife.runtime.js` and `template.js` with your assets (owl needs to
+   be positioned before the templates)
+
+Here is a more detailed explanation on how to compile xml files into a js file:
+
+1. clone the owl repository locally
+2. `npm install` to install all the required tooling
+3. `npm run build:runtime` to build the `owl.iife.runtime.js` file
+4. `npm run build:compiler` to build the template compiler
+5. `npm run compile_templates -- path/to/your/templates` will scan your target
+   folder, find all xml files, get all templates, compile them, and generate a
+   `templates.js` file.
@@ -168,11 +168,15 @@ For each key, a `prop` definition is either a boolean, a constructor, a list of
  - `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.
+  - `optional`: if true, the prop is not mandatory

 There is a special `*` prop that means that additional prop are allowed. This is
 sometimes useful for generic components that will propagate some or all their
 props to their child components.

+Note that default values cannot be defined for a mandatory props. Doing so will
+result in a prop validation error.
+
 Examples:

 ```js
@@ -190,7 +194,8 @@ class ComponentB extends owl.Component {
      element: {type: Object, shape: {id: Boolean, text: String }
    },
   date: Date,
-   combinedVal: [Number, Boolean]
+   combinedVal: [Number, Boolean],
+   optionalProp: { type: Number, optional: true }
  };

  ...
@@ -238,6 +243,8 @@ class ComponentB extends owl.Component {
  };
 ```

+Note: the props validation code is done by using the [validate utility function](utils.md#validate).
+
 ## Good Practices

 A `props` object is a collection of values that come from the parent. As such,
@@ -5,6 +5,8 @@
 - [Overview](#overview)
 - [`useState`](#usestate)
 - [`reactive`](#reactive)
+- [`markRaw`](#markraw)
+- [`toRaw`](#toraw)

 ## Overview

@@ -23,6 +25,11 @@ To solve this issue, Owl provides two reactivity primitives:

 Most of the time, the `useState` hook is the best solution.

+Since version 2.0, Owl applies the fine grained reactivity at the component
+level: reactive objects received as props are automatically subscribed to by the
+component, so Owl can track which part of these props are consumed by each
+component, and is therefore able to only rerender the impacted components.
+
 ## `useState`

 Let us start by an example of how `useState` could be used:
@@ -78,3 +85,47 @@ obj2.b = 3; // log 'observer1' and 'observer2'

 Obviously, one can use `reactive` on the result of a `useState` if wanted, this
 is the proper way to watch for some state changes.
+
+## `markRaw`
+
+Marks an object so that it is ignored by the reactivity system. This function returns its argument.
+
+```js
+const someObject = markRaw(...);
+const state = useState({
+  a: 1,
+  obj: someObject
+});
+// here, state.obj === someObject
+```
+
+This is useful in some rare cases. For example, some complex and large object such
+that going through the reactivity system may cause a non trivial performance slowdown.
+
+However, use this function with caution: this is an escape hatch from the reactivity
+system, and as such, using it may cause subtle and unintended issues!
+
+## `toRaw`
+
+Given a reactive object, this function returns the underlying, non-reactive,
+corresponding object.
+
+```js
+// in setup
+const state = useState({ value: 1 });
+
+// later:
+const rawState = toRaw(this.state);
+rawState.value = 3; // will NOT be picked up by the reactivity system!!!
+```
+
+Here again, this is useful in some situations where we want to explicitely bypass
+Owl, but using this function means that the responsability of coordinating
+state update is given to the user code, instead of Owl. Subtle bugs may arise!
+
+Also, normal (non-reactive objects) will be directly returned by `toRaw`:
+
+```js
+const obj = { a: 1 };
+console.log(toRaw(obj) === obj); // true
+```
@@ -87,8 +87,8 @@ grandparent of the slot content).

 ## Default Slot

-The first element inside the component which is not a named slot will
-be considered the `default` slot. For example:
+All elements inside the component which are not a named slot will be treated as
+part of the content of the `default` slot. For example:

 ```xml
 <div t-name="Parent">
@@ -110,6 +110,7 @@ One can mix default slot and named slots:
    default content
    <t t-set-slot="footer">
      content for footer slot here
+    </t>
  </Child>
 </div>
 ```
@@ -209,30 +210,51 @@ use this `Notebook` component:
 </Notebook>
 ```

+Slot params works like normal props, so one can use the `.bind` suffix to
+bind a function if needed.
+
 ## Slot scopes

-For other kind of advanced use cases, the content of a slot may depends on some
-specific information specific to the generic component. This is the opposite
-of the slot params.
+For other kinds of advanced use cases, the content of a slot may depends on some
+information specific to the generic component. This is the opposite of the slot
+params.

-To solve this kind of problems, one can use the `t-set-scope` directive along
+To solve this kind of problems, one can use the `t-slot-scope` directive along
 with the `t-set-slot`. This defines the name of a variable that can access
 everything given by the child component:

 ```xml
-<div>
-    <t t-set-slot="foo" t-set-scope="scope">
+<MyComponent>
+    <t t-set-slot="foo" t-slot-scope="scope">
        content
        <t t-esc="scope.bool"/>
        <t t-esc="scope.num"/>
    </t>
-</div>
+</MyComponent>
 ```

 And the child component that includes the slot can provide values like this:

 ```xml
-<div>
-    <t t-slot="foo" bool="other_var" num="5">
-</div>
+<t t-slot="foo" bool="other_var" num="5">
 ```
+
+or this:
+
+```xml
+<t t-slot="foo" t-props="someObject">
+```
+
+In the case of the default slot, you may declare the slot scope directly on the
+component itself:
+
+```xml
+<MyComponent t-slot-scope="scope">
+    content
+    <t t-esc="scope.bool"/>
+    <t t-esc="scope.num"/>
+</MyComponent>
+```
+
+Slot values works like normal props, so one can use the `.bind` suffix to
+bind a function if needed.
@@ -21,6 +21,7 @@
 - [Fragments](#fragments)
 - [Inline templates](#inline-templates)
 - [Rendering svg](#rendering-svg)
+- [Restrictions](#restrictions)

 ## Overview

@@ -289,10 +290,11 @@ If an expression evaluates to a falsy value, it will not be set at all:

 It is sometimes convenient to format an attribute with string interpolation. In
 that case, the `t-attf-` directive can be used. It is useful when we need to mix
-literal and dynamic elements, such as css classes.
+literal and dynamic elements, such as css classes. The dynamic elements can be
+specified with either `{{...}}` or `#{...}`:

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

@@ -674,7 +676,19 @@ This `RootNode` component will then display a live SVG representation of the
 graph described by the `graph` property. Note that there is a recursive structure
 here: the `Node` component uses itself as a subcomponent.

-Note that since SVG needs to be handled in a specific way (its namespace needs
-to be properly set), there is a small constraint for Owl components: if an owl
-component is supposed to be a part of an svg graph, then its root node needs to
-be a `g` tag, so Owl can properly set the namespace.
+**Important note:** Owl needs to properly set the namespace for each svg elements.
+Since Owl compile each template separately, it is not able to determine easily
+if a template is supposed to be included in a svg namespace or not. Therefore,
+Owl depends on a heuristic: if a tag is either `svg`, `g` or `path`, then it will
+be considered as svg. In practice, this means that each component or each sub
+templates (included with `t-call`) should have one of these tag as root tag.
+
+## Restrictions
+
+Note that Owl templates forbid the use of tag and or attributes starting with
+the `block-` string. This restriction prevents name collision with the internal
+code of Owl.
+
+```xml
+<div><block-1>this will not be accepted by Owl</block-1></div>
+```
@@ -54,6 +54,17 @@ For example, one may want to also translate `data-title` attributes. To do that,
 we can define additional attributes with the `translatableAttributes` option:

 ```js
-const app = new App(Root, { templates, tranaslateFn, translatalbeAttributes: ["data-title"] });
+const app = new App(Root, { templates, tranaslateFn, translatableAttributes: ["data-title"] });
 // ...
 ```
+
+It is also possible to remove an attribute from the default list by prefixing it with `-`:
+
+```js
+const app = new App(Root, {
+  templates,
+  tranaslateFn,
+  translatableAttributes: ["data-title", "-title"],
+});
+// data-title attribute will be translated, but not title attribute...
+```
@@ -8,6 +8,7 @@ functions are all available in the `owl.utils` namespace.
 - [`whenReady`](#whenready): executing code when DOM is ready
 - [`loadFile`](#loadfile): loading a file (useful for templates)
 - [`EventBus`](#eventbus): a simple EventBus
+- [`validate`](#validate): a validation function

 ## `whenReady`

@@ -56,3 +57,24 @@ bus.addEventListener("event", () => console.log("something happened"));

 bus.trigger("event"); // 'something happened' is logged
 ```
+
+## `validate`
+
+The `validate` function is a function that validates if a given object satisfies a
+specified schema. It is actually used by Owl itself to perform
+[props validation](props.md#props-validation). For example:
+
+```js
+validate(
+  { a: "hey" },
+  {
+    id: Number,
+    url: [Boolean, { type: Array, element: Number }],
+  }
+);
+
+// throws an error with the following information:
+//    - unknown key 'a',
+//    - 'id' is missing (should be a number),
+//    - 'url' is missing (should be a boolean or list of numbers),
+```
@@ -1,11 +1,11 @@
 {
  "name": "@odoo/owl",
-  "version": "2.0.0-alpha1",
+  "version": "2.0.0-beta-9",
  "description": "Odoo Web Library (OWL)",
  "main": "dist/owl.cjs.js",
  "browser": "dist/owl.iife.js",
  "module": "dist/owl.es.js",
-  "types": "dist/types/index.d.ts",
+  "types": "dist/types/owl.d.ts",
  "files": [
    "dist"
  ],
@@ -14,6 +14,8 @@
  },
  "scripts": {
    "build:bundle": "rollup -c --failAfterWarnings",
+    "build:runtime": "rollup -c --failAfterWarnings runtime",
+    "build:compiler": "rollup -c --failAfterWarnings compiler",
    "build": "npm run build:bundle",
    "test": "jest",
    "test:debug": "node --inspect-brk node_modules/.bin/jest --runInBand --watch --testTimeout=5000000",
@@ -25,7 +27,8 @@
    "prettier": "prettier {src/*.ts,src/**/*.ts,tests/*.ts,tests/**/*.ts,doc/*.md,doc/**/*.md} --write",
    "check-formatting": "prettier {src/*.ts,src/**/*.ts,tests/*.ts,tests/**/*.ts,doc/*.md,doc/**/*.md} --check",
    "publish": "npm run build && npm publish",
-    "release": "node tools/release.js"
+    "release": "node tools/release.js",
+    "compile_templates": "node tools/compile_xml.js"
  },
  "repository": {
    "type": "git",
@@ -52,6 +55,7 @@
    "npm-run-all": "^4.1.5",
    "prettier": "2.4.1",
    "rollup": "^2.56.3",
+    "rollup-plugin-dts": "^4.2.2",
    "rollup-plugin-terser": "^7.0.2",
    "rollup-plugin-typescript2": "^0.31.1",
    "sass": "^1.16.1",
@@ -1,6 +1,6 @@
 # 🦉 OWL Roadmap 🦉

- Current version: 1.4.7
+- Current version: 1.4.10
 - Status: stable

 This roadmap is only an attempt at predicting Owl's future.  Everything may
@@ -2,14 +2,10 @@ import pkg from "./package.json";
 import git from "git-rev-sync";
 import typescript from 'rollup-plugin-typescript2';
 import { terser } from "rollup-plugin-terser";
+import dts from "rollup-plugin-dts";

-const name = "owl";
-const extend = true;
+let input, output;

-/**
- * Meta data to be added on the __info__ object.
- * Used to let external tools know the current owl version.
- */
 const outro = `
 __info__.version = '${pkg.version}';
 __info__.date = '${new Date().toISOString()}';
@@ -17,13 +13,39 @@ __info__.hash = '${git.short()}';
 __info__.url = 'https://github.com/odoo/owl';
 `;

+switch (process.argv[4]) {
+  case "compiler": 
+    input = "src/compiler/index.ts",
+    output = [
+      getConfigForFormat('cjs', 'dist/compiler.js', ''),
+    ]
+    break;
+  case "runtime":
+    input = "src/runtime/index.ts";
+    output = [
+      getConfigForFormat('esm', addSuffix(pkg.module,  'runtime'), outro),
+      getConfigForFormat('cjs', addSuffix(pkg.main,  'runtime'), outro),
+      getConfigForFormat('iife', addSuffix(pkg.browser,  'runtime'), outro),
+      getConfigForFormat('iife', addSuffix(pkg.browser,  'runtime'), outro, true),
+    ]
+    break;
+  default:
+    input = "src/index.ts",
+    output = [
+      getConfigForFormat('esm', pkg.module, outro),
+      getConfigForFormat('cjs', pkg.main, outro),
+      getConfigForFormat('iife', pkg.browser, outro),
+      getConfigForFormat('iife', pkg.browser, outro, true),
+    ]
+  }
+
 /**
 * Generate from a string depicting a path a new path for the minified version.
 * @param {string} pkgFileName file name
 */
-function generateMinifiedNameFromPkgName(pkgFileName) {
+function addSuffix(pkgFileName, suffix) {
  const parts = pkgFileName.split('.');
-  parts.splice(parts.length - 1, 0, "min");
+  parts.splice(parts.length - 1, 0, suffix);
  return parts.join('.');
 }

@@ -33,12 +55,12 @@ function generateMinifiedNameFromPkgName(pkgFileName) {
 * @param {string} generatedFileName generated file name
 * @param {boolean} minified should it be minified
 */
-function getConfigForFormat(format, generatedFileName, minified = false) {
+function getConfigForFormat(format, generatedFileName, outro, minified = false) {
  return {
-    file: minified ? generateMinifiedNameFromPkgName(generatedFileName) : generatedFileName,
+    file: minified ? addSuffix(generatedFileName, "min") : generatedFileName,
    format: format,
-    name: name,
-    extend: extend,
+    name: "owl",
+    extend: true,
    outro: outro,
    freeze: false,
    plugins: minified ? [terser()] : [],
@@ -46,26 +68,19 @@ function getConfigForFormat(format, generatedFileName, minified = false) {
  };
 }

-export default {
-  input: "src/index.ts",
-  output: [
-
-    /**
-     * Read about module formats:
-     *  https://auth0.com/blog/javascript-module-systems-showdown/
-     *  https://medium.com/@kelin2025/so-you-wanna-use-es6-modules-714f48b3a953
-     */
-
-    getConfigForFormat('esm', pkg.module),
-    getConfigForFormat('esm', pkg.module, true),
-    getConfigForFormat('cjs', pkg.main),
-    getConfigForFormat('cjs', pkg.main, true),
-    getConfigForFormat('iife', pkg.browser),
-    getConfigForFormat('iife', pkg.browser, true),
-  ],
-  plugins: [
-    typescript({
-      useTsconfigDeclarationDir: true
-    }),
-  ]
-};
+export default [
+  {
+    input,
+    output,
+    plugins: [
+      typescript({
+        useTsconfigDeclarationDir: true
+      }),
+    ]
+  },
+  {
+    input: "dist/types/index.d.ts",
+    output: [{ file: "dist/types/owl.d.ts", format: "es" }],
+    plugins: [dts()],
+  },
+];
@@ -1,105 +0,0 @@
-import { Component } from "../component/component";
-import { ComponentNode } from "../component/component_node";
-import { MountOptions } from "../component/fibers";
-import { Scheduler } from "../component/scheduler";
-import { TemplateSet, TemplateSetConfig } from "./template_set";
-import { nodeErrorHandlers } from "../component/error_handling";
-
-// reimplement dev mode stuff see last change in 0f7a8289a6fb8387c3c1af41c6664b2a8448758f
-
-export interface Env {
-  [key: string]: any;
-}
-
-export interface AppConfig extends TemplateSetConfig {
-  env?: Env;
-  props?: any;
-}
-
-export const DEV_MSG = `Owl is running in 'dev' mode.
-
-This is not suitable for production use.
-See https://github.com/odoo/owl/blob/master/doc/reference/config.md#mode for more information.`;
-
-export class App<T extends typeof Component = any> extends TemplateSet {
-  Root: T;
-  props: any;
-  env: Env;
-  scheduler = new Scheduler();
-  root: ComponentNode | null = null;
-
-  constructor(Root: T, config: AppConfig = {}) {
-    super(config);
-    this.Root = Root;
-    if (config.dev) {
-      console.info(DEV_MSG);
-    }
-    const descrs = Object.getOwnPropertyDescriptors(config.env || {});
-    this.env = Object.freeze(Object.defineProperties({}, descrs));
-    this.props = config.props || {};
-  }
-
-  mount(target: HTMLElement, options?: MountOptions): Promise<InstanceType<T>> {
-    this.checkTarget(target);
-    const node = this.makeNode(this.Root, this.props);
-    const prom = this.mountNode(node, target, options);
-    this.root = node;
-    return prom;
-  }
-
-  checkTarget(target: HTMLElement) {
-    if (!(target instanceof HTMLElement)) {
-      throw new Error("Cannot mount component: the target is not a valid DOM element");
-    }
-    if (!document.body.contains(target)) {
-      throw new Error("Cannot mount a component on a detached dom node");
-    }
-  }
-
-  makeNode(Component: T, props: any): ComponentNode {
-    return new ComponentNode(Component, props, this);
-  }
-
-  mountNode(node: ComponentNode, target: HTMLElement, options?: MountOptions) {
-    const promise: any = new Promise((resolve, reject) => {
-      let isResolved = false;
-      // manually set a onMounted callback.
-      // that way, we are independant from the current node.
-      node.mounted.push(() => {
-        resolve(node.component);
-        isResolved = true;
-      });
-
-      // Manually add the last resort error handler on the node
-      let handlers = nodeErrorHandlers.get(node);
-      if (!handlers) {
-        handlers = [];
-        nodeErrorHandlers.set(node, handlers);
-      }
-      handlers.unshift((e) => {
-        if (isResolved) {
-          console.error(e);
-        } else {
-          reject(e);
-        }
-        throw e;
-      });
-    });
-    node.mountComponent(target, options);
-    return promise;
-  }
-
-  destroy() {
-    if (this.root) {
-      this.root.destroy();
-    }
-  }
-}
-
-export async function mount<T extends typeof Component>(
-  C: T,
-  target: HTMLElement,
-  config: AppConfig & MountOptions = {}
-): Promise<InstanceType<T>> {
-  return new App(C, config).mount(target, config);
-}
@@ -1,4 +1,10 @@
-import { compileExpr, compileExprToArray, interpolate, INTERP_REGEXP } from "./inline_expressions";
+import {
+  compileExpr,
+  compileExprToArray,
+  interpolate,
+  INTERP_REGEXP,
+  replaceDynamicParts,
+} from "./inline_expressions";
 import {
  AST,
  ASTComment,
@@ -20,6 +26,8 @@ import {
  ASTTranslation,
  ASTType,
  ASTTPortal,
+  EventHandlers,
+  Attrs,
 } from "./parser";

 type BlockType = "block" | "text" | "multi" | "list" | "html" | "comment";
@@ -33,7 +41,6 @@ export interface Config {
 export interface CodeGenOptions extends Config {
  hasSafeContext?: boolean;
  name?: string;
-  nameSpace?: string;
 }

 // using a non-html document so that <inner/outer>HTML serializes as XML instead
@@ -41,17 +48,20 @@ export interface CodeGenOptions extends Config {
 const xmlDoc = document.implementation.createDocument(null, null, null);

 const MODS = new Set(["stop", "capture", "prevent", "self", "synthetic"]);
+
+let nextDataIds: { [key: string]: number } = {};
+
+function generateId(prefix: string = "") {
+  nextDataIds[prefix] = (nextDataIds[prefix] || 0) + 1;
+  return prefix + nextDataIds[prefix];
+}
+
 // -----------------------------------------------------------------------------
 // BlockDescription
 // -----------------------------------------------------------------------------

 class BlockDescription {
  static nextBlockId = 1;
-  static nextDataIds: { [key: string]: number } = {};
-  static generateId(prefix: string) {
-    this.nextDataIds[prefix] = (this.nextDataIds[prefix] || 0) + 1;
-    return prefix + this.nextDataIds[prefix];
-  }

  varName: string;
  blockName: string;
@@ -77,7 +87,7 @@ class BlockDescription {
  }

  insertData(str: string, prefix: string = "d"): number {
-    const id = BlockDescription.generateId(prefix);
+    const id = generateId(prefix);
    this.target.addLine(`let ${id} = ${str};`);
    return this.data.push(id) - 1;
  }
@@ -129,6 +139,7 @@ interface Context {
  translate: boolean;
  tKeyExpr: string | null;
  nameSpace?: string;
+  tModelSelectedExpr?: string;
 }

 function createContext(parentCtx: Context, params?: Partial<Context>) {
@@ -140,6 +151,7 @@ function createContext(parentCtx: Context, params?: Partial<Context>) {
      translate: parentCtx.translate,
      tKeyExpr: null,
      nameSpace: parentCtx.nameSpace,
+      tModelSelectedExpr: parentCtx.tModelSelectedExpr,
    },
    params
  );
@@ -156,9 +168,11 @@ class CodeTarget {
  // maps ref name to [id, expr]
  refInfo: { [name: string]: [string, string] } = {};
  shouldProtectScope: boolean = false;
+  on: EventHandlers | null;

-  constructor(name: string) {
+  constructor(name: string, on?: EventHandlers | null) {
    this.name = name;
+    this.on = on || null;
  }

  addLine(line: string, idx?: number) {
@@ -204,7 +218,6 @@ const translationRE = /^(\s*)([\s\S]+?)(\s*)$/;

 export class CodeGenerator {
  blocks: BlockDescription[] = [];
-  ids: { [key: string]: number } = {};
  nextBlockId = 1;
  hasSafeContext: boolean;
  isDebug: boolean = false;
@@ -213,28 +226,35 @@ export class CodeGenerator {
  templateName?: string;
  dev: boolean;
  translateFn: (s: string) => string;
-  translatableAttributes: string[];
+  translatableAttributes: string[] = TRANSLATABLE_ATTRS;
  ast: AST;
-  staticCalls: { id: string; template: string, nameSpace?: string }[] = [];
+  staticDefs: { id: string; expr: string }[] = [];
  helpers: Set<string> = new Set();
-  nameSpace?: string;

  constructor(ast: AST, options: CodeGenOptions) {
    this.translateFn = options.translateFn || ((s: string) => s);
-    this.translatableAttributes = options.translatableAttributes || TRANSLATABLE_ATTRS;
+    if (options.translatableAttributes) {
+      const attrs = new Set(TRANSLATABLE_ATTRS);
+      for (let attr of options.translatableAttributes) {
+        if (attr.startsWith("-")) {
+          attrs.delete(attr.slice(1));
+        } else {
+          attrs.add(attr);
+        }
+      }
+      this.translatableAttributes = [...attrs];
+    }
    this.hasSafeContext = options.hasSafeContext || false;
    this.dev = options.dev || false;
    this.ast = ast;
    this.templateName = options.name;
-    this.nameSpace = options.nameSpace;
-    console.log('ThisNS', this.nameSpace)
  }

  generateCode(): string {
    const ast = this.ast;
    this.isDebug = ast.type === ASTType.TDebug;
    BlockDescription.nextBlockId = 1;
-    BlockDescription.nextDataIds = {};
+    nextDataIds = {};
    this.compileAST(ast, {
      block: null,
      index: 0,
@@ -242,7 +262,6 @@ export class CodeGenerator {
      isLast: true,
      translate: true,
      tKeyExpr: null,
-      nameSpace: this.nameSpace,
    });
    // define blocks and utility functions
    let mainCode = [
@@ -255,12 +274,8 @@ export class CodeGenerator {
      mainCode.push(`// Template name: "${this.templateName}"`);
    }

-    for (let { id, template, nameSpace } of this.staticCalls) {
-      let ns;
-      if (nameSpace) {
-        ns = `, "${nameSpace}"`;
-      }
-      mainCode.push(`const ${id} = getTemplate(${template}${ns});`);
+    for (let { id, expr } of this.staticDefs) {
+      mainCode.push(`const ${id} = ${expr};`);
    }

    // define all blocks
@@ -300,25 +315,23 @@ export class CodeGenerator {
    return code;
  }

-  compileInNewTarget(prefix: string, ast: AST, ctx: Context): string {
-    const name = this.generateId(prefix);
+  compileInNewTarget(prefix: string, ast: AST, ctx: Context, on?: EventHandlers | null): string {
+    const name = generateId(prefix);
    const initialTarget = this.target;
-    const target = new CodeTarget(name);
+    const target = new CodeTarget(name, on);
    this.targets.push(target);
    this.target = target;
-    const subCtx: Context = createContext(ctx);
-    this.compileAST(ast, subCtx);
+    this.compileAST(ast, createContext(ctx));
    this.target = initialTarget;
    return name;
  }

-  addLine(line: string) {
-    this.target.addLine(line);
+  addLine(line: string, idx?: number) {
+    this.target.addLine(line, idx);
  }

-  generateId(prefix: string = ""): string {
-    this.ids[prefix] = (this.ids[prefix] || 0) + 1;
-    return prefix + this.ids[prefix];
+  define(varName: string, expr: string) {
+    this.addLine(`const ${varName} = ${expr};`);
  }

  insertAnchor(block: BlockDescription) {
@@ -365,9 +378,12 @@ export class CodeGenerator {
    }

    if (block.isRoot && !ctx.preventRoot) {
+      if (this.target.on) {
+        blockExpr = this.wrapWithEventCatcher(blockExpr, this.target.on);
+      }
      this.addLine(`return ${blockExpr};`);
    } else {
-      this.addLine(`let ${block.varName} = ${blockExpr};`);
+      this.define(block.varName, blockExpr);
    }
  }

@@ -394,9 +410,9 @@ export class CodeGenerator {
      .map((tok) => {
        if (tok.varName && !tok.isLocal) {
          if (!mapping.has(tok.varName)) {
-            const varId = this.generateId("v");
+            const varId = generateId("v");
            mapping.set(tok.varName, varId);
-            this.addLine(`const ${varId} = ${tok.value};`);
+            this.define(varId, tok.value);
          }
          tok.value = mapping.get(tok.varName)!;
        }
@@ -531,46 +547,57 @@ export class CodeGenerator {

  compileTDomNode(ast: ASTDomNode, ctx: Context) {
    let { block, forceNewBlock } = ctx;
-    const isNewBlock = !block || forceNewBlock || ast.dynamicTag !== null;
+    const isNewBlock = !block || forceNewBlock || ast.dynamicTag !== null || ast.ns;
    let codeIdx = this.target.code.length;
    if (isNewBlock) {
-      if ((ast.dynamicTag || ctx.tKeyExpr) && ctx.block) {
+      if ((ast.dynamicTag || ctx.tKeyExpr || ast.ns) && ctx.block) {
        this.insertAnchor(ctx.block!);
      }
      block = this.createBlock(block, "block", ctx);
      this.blocks.push(block);
      if (ast.dynamicTag) {
-        const tagExpr = this.generateId("tag");
-        this.addLine(`let ${tagExpr} = ${compileExpr(ast.dynamicTag)};`);
+        const tagExpr = generateId("tag");
+        this.define(tagExpr, compileExpr(ast.dynamicTag));
        block.dynamicTagName = tagExpr;
      }
    }
    // attributes
-    const attrs: { [key: string]: string } = {};
+    const attrs: Attrs = {};
    const nameSpace = ast.ns || ctx.nameSpace;
-    console.log(nameSpace)
    if (nameSpace && isNewBlock) {
      // specific namespace uri
      attrs["block-ns"] = nameSpace;
    }
+
    for (let key in ast.attrs) {
+      let expr, attrName;
      if (key.startsWith("t-attf")) {
-        let expr = interpolate(ast.attrs[key]);
+        expr = interpolate(ast.attrs[key]);
        const idx = block!.insertData(expr, "attr");
-        attrs["block-attribute-" + idx] = key.slice(7);
+
+        attrName = key.slice(7);
+        attrs["block-attribute-" + idx] = attrName;
      } else if (key.startsWith("t-att")) {
-        let expr = compileExpr(ast.attrs[key]);
+        expr = compileExpr(ast.attrs[key]);
        const idx = block!.insertData(expr, "attr");
        if (key === "t-att") {
          attrs[`block-attributes`] = String(idx);
        } else {
-          attrs[`block-attribute-${idx}`] = key.slice(6);
+          attrName = key.slice(6);
+          attrs[`block-attribute-${idx}`] = attrName;
        }
      } else if (this.translatableAttributes.includes(key)) {
        attrs[key] = this.translateFn(ast.attrs[key]);
      } else {
+        expr = `"${ast.attrs[key]}"`;
+        attrName = key;
        attrs[key] = ast.attrs[key];
      }
+
+      if (attrName === "value" && ctx.tModelSelectedExpr) {
+        let selectedId = block!.insertData(`${ctx.tModelSelectedExpr} === ${expr}`, "attr");
+        attrs[`block-attribute-${selectedId}`] = "selected";
+      }
    }

    // event handlers
@@ -585,11 +612,8 @@ export class CodeGenerator {
      this.target.hasRef = true;
      const isDynamic = INTERP_REGEXP.test(ast.ref);
      if (isDynamic) {
-        const str = ast.ref.replace(
-          INTERP_REGEXP,
-          (expr) => "${" + this.captureExpression(expr.slice(2, -2), true) + "}"
-        );
-        const idx = block!.insertData(`(el) => refs[\`${str}\`] = el`, "ref");
+        const str = replaceDynamicParts(ast.ref, (expr) => this.captureExpression(expr, true));
+        const idx = block!.insertData(`(el) => refs[${str}] = el`, "ref");
        attrs["block-ref"] = String(idx);
      } else {
        let name = ast.ref;
@@ -601,7 +625,7 @@ export class CodeGenerator {
          attrs["block-ref"] = String(index);
          info[1] = `multiRefSetter(refs, \`${name}\`)`;
        } else {
-          let id = this.generateId("ref");
+          let id = generateId("ref");
          this.target.refInfo[name] = [id, `(el) => refs[\`${name}\`] = el`];
          const index = block!.data.push(id) - 1;
          attrs["block-ref"] = String(index);
@@ -610,8 +634,10 @@ export class CodeGenerator {
    }

    // t-model
+    let tModelSelectedExpr;
    if (ast.model) {
      const {
+        hasDynamicChildren,
        baseExpr,
        expr,
        eventType,
@@ -622,20 +648,25 @@ export class CodeGenerator {
      } = ast.model;

      const baseExpression = compileExpr(baseExpr);
-      const id = this.generateId();
-      this.addLine(`const bExpr${id} = ${baseExpression};`);
+      const bExprId = generateId("bExpr");
+      this.define(bExprId, baseExpression);

      const expression = compileExpr(expr);
+      const exprId = generateId("expr");
+      this.define(exprId, expression);
+
+      const fullExpression = `${bExprId}[${exprId}]`;

      let idx: number;
      if (specialInitTargetAttr) {
-        idx = block!.insertData(
-          `${baseExpression}[${expression}] === '${attrs[targetAttr]}'`,
-          "attr"
-        );
+        idx = block!.insertData(`${fullExpression} === '${attrs[targetAttr]}'`, "attr");
        attrs[`block-attribute-${idx}`] = specialInitTargetAttr;
+      } else if (hasDynamicChildren) {
+        const bValueId = generateId("bValue");
+        tModelSelectedExpr = `${bValueId}`;
+        this.define(tModelSelectedExpr, fullExpression);
      } else {
-        idx = block!.insertData(`${baseExpression}[${expression}]`, "attr");
+        idx = block!.insertData(`${fullExpression}`, "attr");
        attrs[`block-attribute-${idx}`] = targetAttr;
      }
      this.helpers.add("toNumber");
@@ -643,7 +674,7 @@ export class CodeGenerator {
      valueCode = shouldTrim ? `${valueCode}.trim()` : valueCode;
      valueCode = shouldNumberize ? `toNumber(${valueCode})` : valueCode;

-      const handler = `[(ev) => { bExpr${id}[${expression}] = ${valueCode}; }]`;
+      const handler = `[(ev) => { ${fullExpression} = ${valueCode}; }]`;
      idx = block!.insertData(handler, "hdlr");
      attrs[`block-handler-${idx}`] = eventType;
    }
@@ -668,6 +699,7 @@ export class CodeGenerator {
          isLast: ctx.isLast && i === children.length - 1,
          tKeyExpr: ctx.tKeyExpr,
          nameSpace,
+          tModelSelectedExpr,
        });
        this.compileAST(child, subCtx);
      }
@@ -682,13 +714,13 @@ export class CodeGenerator {
        const children = block!.children.slice();
        let current = children.shift();
        for (let i = codeIdx; i < code.length; i++) {
-          if (code[i].trimStart().startsWith(`let ${current!.varName} `)) {
-            code[i] = code[i].replace(`let ${current!.varName}`, current!.varName);
+          if (code[i].trimStart().startsWith(`const ${current!.varName} `)) {
+            code[i] = code[i].replace(`const ${current!.varName}`, current!.varName);
            current = children.shift();
            if (!current) break;
          }
        }
-        this.target.addLine(`let ${block!.children.map((c) => c.varName)};`, codeIdx);
+        this.addLine(`let ${block!.children.map((c) => c.varName)};`, codeIdx);
      }
    }
  }
@@ -777,13 +809,13 @@ export class CodeGenerator {
        const children = block!.children.slice();
        let current = children.shift();
        for (let i = codeIdx; i < code.length; i++) {
-          if (code[i].trimStart().startsWith(`let ${current!.varName} `)) {
-            code[i] = code[i].replace(`let ${current!.varName}`, current!.varName);
+          if (code[i].trimStart().startsWith(`const ${current!.varName} `)) {
+            code[i] = code[i].replace(`const ${current!.varName}`, current!.varName);
            current = children.shift();
            if (!current) break;
          }
        }
-        this.target.addLine(`let ${block!.children.map((c) => c.varName)};`, codeIdx);
+        this.addLine(`let ${block!.children.map((c) => c.varName)};`, codeIdx);
      }

      // note: this part is duplicated from end of compilemulti:
@@ -806,12 +838,10 @@ export class CodeGenerator {
    const l = `l_block${block.id}`;
    const c = `c_block${block.id}`;
    this.helpers.add("prepareList");
-    this.addLine(
-      `const [${keys}, ${vals}, ${l}, ${c}] = prepareList(${compileExpr(ast.collection)});`
-    );
+    this.define(`[${keys}, ${vals}, ${l}, ${c}]`, `prepareList(${compileExpr(ast.collection)});`);
    // Throw errors on duplicate keys in dev mode
    if (this.dev) {
-      this.addLine(`const keys${block.id} = new Set();`);
+      this.define(`keys${block.id}`, `new Set()`);
    }
    this.addLine(`for (let ${loopVar} = 0; ${loopVar} < ${l}; ${loopVar}++) {`);
    this.target.indentLevel++;
@@ -828,7 +858,7 @@ export class CodeGenerator {
    if (!ast.hasNoValue) {
      this.addLine(`ctx[\`${ast.elem}_value\`] = ${keys}[${loopVar}];`);
    }
-    this.addLine(`let key${this.target.loopLevel} = ${ast.key ? compileExpr(ast.key) : loopVar};`);
+    this.define(`key${this.target.loopLevel}`, ast.key ? compileExpr(ast.key) : loopVar);
    if (this.dev) {
      // Throw error on duplicate keys in dev mode
      this.addLine(
@@ -839,9 +869,9 @@ export class CodeGenerator {
    let id: string;
    if (ast.memo) {
      this.target.hasCache = true;
-      id = this.generateId();
-      this.addLine(`let memo${id} = ${compileExpr(ast.memo)}`);
-      this.addLine(`let vnode${id} = cache[key${this.target.loopLevel}];`);
+      id = generateId();
+      this.define(`memo${id}`, compileExpr(ast.memo));
+      this.define(`vnode${id}`, `cache[key${this.target.loopLevel}];`);
      this.addLine(`if (vnode${id}) {`);
      this.target.indentLevel++;
      this.addLine(`if (shallowEqual(vnode${id}.memo, memo${id})) {`);
@@ -874,8 +904,8 @@ export class CodeGenerator {
  }

  compileTKey(ast: ASTTKey, ctx: Context) {
-    const tKeyExpr = this.generateId("tKey_");
-    this.addLine(`const ${tKeyExpr} = ${compileExpr(ast.expr)};`);
+    const tKeyExpr = generateId("tKey_");
+    this.define(tKeyExpr, compileExpr(ast.expr));
    ctx = createContext(ctx, {
      tKeyExpr,
      block: ctx.block,
@@ -921,13 +951,13 @@ export class CodeGenerator {
          const children = block!.children.slice();
          let current = children.shift();
          for (let i = codeIdx; i < code.length; i++) {
-            if (code[i].trimStart().startsWith(`let ${current!.varName} `)) {
-              code[i] = code[i].replace(`let ${current!.varName}`, current!.varName);
+            if (code[i].trimStart().startsWith(`const ${current!.varName} `)) {
+              code[i] = code[i].replace(`const ${current!.varName}`, current!.varName);
              current = children.shift();
              if (!current) break;
            }
          }
-          this.target.addLine(`let ${block!.children.map((c) => c.varName)};`, codeIdx);
+          this.addLine(`let ${block!.children.map((c) => c.varName)};`, codeIdx);
        }
      }

@@ -959,18 +989,19 @@ export class CodeGenerator {
    }
    const key = `key + \`${this.generateComponentKey()}\``;
    if (isDynamic) {
-      const templateVar = this.generateId("template");
-      this.addLine(`const ${templateVar} = ${subTemplate};`);
+      const templateVar = generateId("template");
+      if (!this.staticDefs.find((d) => d.id === "call")) {
+        this.staticDefs.push({ id: "call", expr: `app.callTemplate.bind(app)` });
+      }
+      this.define(templateVar, subTemplate);
      block = this.createBlock(block, "multi", ctx);
-      this.helpers.add("call");
      this.insertBlock(`call(this, ${templateVar}, ctx, node, ${key})`, block!, {
        ...ctx,
        forceNewBlock: !block,
      });
    } else {
-      const id = this.generateId(`callTemplate_`);
-      this.helpers.add("getTemplate");
-      this.staticCalls.push({ id, template: subTemplate, nameSpace: ctx.nameSpace });
+      const id = generateId(`callTemplate_`);
+      this.staticDefs.push({ id, expr: `app.getTemplate(${subTemplate})` });
      block = this.createBlock(block, "multi", ctx);
      this.insertBlock(`${id}.call(this, ctx, node, ${key})`, block!, {
        ...ctx,
@@ -1021,61 +1052,83 @@ export class CodeGenerator {
  }

  generateComponentKey() {
-    const parts = [this.generateId("__")];
+    const parts = [generateId("__")];
    for (let i = 0; i < this.target.loopLevel; i++) {
      parts.push(`\${key${i + 1}}`);
    }
    return parts.join("__");
  }

-  compileComponent(ast: ASTComponent, ctx: Context) {
-    let { block } = ctx;
-
-    // props
-    const props: string[] = [];
-    let hasSlotsProp = false;
-    for (let propName in ast.props) {
-      let propValue = this.captureExpression(ast.props[propName]) || undefined;
-      if (propName.includes(".")) {
-        let [name, suffix] = propName.split(".");
-        if (suffix === "bind") {
-          this.helpers.add("bind");
-          propName = name;
-          propValue = `bind(ctx, ${propValue})`;
-        } else {
-          throw new Error("Invalid prop suffix");
-        }
-      }
-      propName = /^[a-z_]+$/i.test(propName) ? propName : `'${propName}'`;
-      props.push(`${propName}: ${propValue}`);
-      if (propName === "slots") {
-        hasSlotsProp = true;
+  /**
+   * Formats a prop name and value into a string suitable to be inserted in the
+   * generated code. For example:
+   *
+   * Name              Value            Result
+   * ---------------------------------------------------------
+   * "number"          "state"          "number: ctx['state']"
+   * "something"       ""               "something: undefined"
+   * "some-prop"       "state"          "'some-prop': ctx['state']"
+   * "onClick.bind"    "onClick"        "onClick: bind(ctx, ctx['onClick'])"
+   */
+  formatProp(name: string, value: string): string {
+    value = this.captureExpression(value);
+    if (name.includes(".")) {
+      let [_name, suffix] = name.split(".");
+      if (suffix === "bind") {
+        this.helpers.add("bind");
+        name = _name;
+        value = `bind(ctx, ${value || undefined})`;
+      } else {
+        throw new Error("Invalid prop suffix");
      }
    }
+    name = /^[a-z_]+$/i.test(name) ? name : `'${name}'`;
+    return `${name}: ${value || undefined}`;
+  }
+
+  formatPropObject(obj: { [prop: string]: any }): string[] {
+    return Object.entries(obj).map(([k, v]) => this.formatProp(k, v));
+  }
+
+  getPropString(props: string[], dynProps: string | null): string {
+    let propString = `{${props.join(",")}}`;
+    if (dynProps) {
+      propString = `Object.assign({}, ${compileExpr(dynProps)}${
+        props.length ? ", " + propString : ""
+      })`;
+    }
+    return propString;
+  }
+
+  compileComponent(ast: ASTComponent, ctx: Context) {
+    let { block } = ctx;
+    // props
+    const hasSlotsProp = "slots" in (ast.props || {});
+    const props: string[] = ast.props ? this.formatPropObject(ast.props) : [];

    // slots
-    const hasSlot = !!Object.keys(ast.slots).length;
    let slotDef: string = "";
-    if (hasSlot) {
+    if (ast.slots) {
      let ctxStr = "ctx";
      if (this.target.loopLevel || !this.hasSafeContext) {
-        ctxStr = this.generateId("ctx");
+        ctxStr = generateId("ctx");
        this.helpers.add("capture");
-        this.addLine(`const ${ctxStr} = capture(ctx);`);
+        this.define(ctxStr, `capture(ctx)`);
      }
      let slotStr: string[] = [];
      for (let slotName in ast.slots) {
-        const slotAst = ast.slots[slotName].content;
-        const name = this.compileInNewTarget("slot", slotAst, ctx);
-        const params = [`__render: ${name}, __ctx: ${ctxStr}`];
+        const slotAst = ast.slots[slotName];
+        const params = [];
+        if (slotAst.content) {
+          const name = this.compileInNewTarget("slot", slotAst.content, ctx, slotAst.on);
+          params.push(`__render: ${name}, __ctx: ${ctxStr}`);
+        }
        const scope = ast.slots[slotName].scope;
        if (scope) {
          params.push(`__scope: "${scope}"`);
        }
        if (ast.slots[slotName].attrs) {
-          for (const [n, v] of Object.entries(ast.slots[slotName].attrs!)) {
-            params.push(`${n}: ${compileExpr(v) || undefined}`);
-          }
+          params.push(...this.formatPropObject(ast.slots[slotName].attrs!));
        }
        const slotInfo = `{${params.join(", ")}}`;
        slotStr.push(`'${slotName}': ${slotInfo}`);
@@ -1084,43 +1137,36 @@ export class CodeGenerator {
    }

    if (slotDef && !(ast.dynamicProps || hasSlotsProp)) {
-      props.push(`slots: ${slotDef}`);
+      this.helpers.add("markRaw");
+      props.push(`slots: markRaw(${slotDef})`);
    }

-    const propStr = `{${props.join(",")}}`;
-
-    let propString = propStr;
-    if (ast.dynamicProps) {
-      if (!props.length) {
-        propString = `${compileExpr(ast.dynamicProps)}`;
-      } else {
-        propString = `Object.assign({}, ${compileExpr(ast.dynamicProps)}, ${propStr})`;
-      }
-    }
+    let propString = this.getPropString(props, ast.dynamicProps);

    let propVar: string;
    if ((slotDef && (ast.dynamicProps || hasSlotsProp)) || this.dev) {
-      propVar = this.generateId("props");
-      this.addLine(`const ${propVar!} = ${propString}`);
+      propVar = generateId("props");
+      this.define(propVar!, propString);
      propString = propVar!;
    }

    if (slotDef && (ast.dynamicProps || hasSlotsProp)) {
-      this.addLine(`${propVar!}.slots = Object.assign(${slotDef}, ${propVar!}.slots)`);
+      this.helpers.add("markRaw");
+      this.addLine(`${propVar!}.slots = markRaw(Object.assign(${slotDef}, ${propVar!}.slots))`);
    }

    // cmap key
    const key = this.generateComponentKey();
    let expr: string;
    if (ast.isDynamic) {
-      expr = this.generateId("Comp");
-      this.addLine(`let ${expr} = ${compileExpr(ast.name)};`);
+      expr = generateId("Comp");
+      this.define(expr, compileExpr(ast.name));
    } else {
      expr = `\`${ast.name}\``;
    }

    if (this.dev) {
-      this.addLine(`helpers.validateProps(${expr}, ${propVar!}, ctx)`);
+      this.addLine(`helpers.validateProps(${expr}, ${propVar!}, ctx);`);
    }

    if (block && (ctx.forceNewBlock === false || ctx.tKeyExpr)) {
@@ -1137,10 +1183,32 @@ export class CodeGenerator {
    if (ast.isDynamic) {
      blockExpr = `toggler(${expr}, ${blockExpr})`;
    }
+
+    // event handling
+    if (ast.on) {
+      blockExpr = this.wrapWithEventCatcher(blockExpr, ast.on);
+    }
+
    block = this.createBlock(block, "multi", ctx);
    this.insertBlock(blockExpr, block, ctx);
  }

+  wrapWithEventCatcher(expr: string, on: EventHandlers): string {
+    this.helpers.add("createCatcher");
+    let name = generateId("catcher");
+    let spec: any = {};
+    let handlers: any[] = [];
+    for (let ev in on) {
+      let handlerId = generateId("hdlr");
+      let idx = handlers.push(handlerId) - 1;
+      spec[ev] = idx;
+      const handler = this.generateHandlerCode(ev, on[ev]);
+      this.define(handlerId, handler);
+    }
+    this.staticDefs.push({ id: name, expr: `createCatcher(${JSON.stringify(spec)})` });
+    return `${name}(${expr}, [${handlers.join(",")}])`;
+  }
+
  compileTSlot(ast: ASTSlot, ctx: Context) {
    this.helpers.add("callSlot");
    let { block } = ctx;
@@ -1153,28 +1221,29 @@ export class CodeGenerator {
    } else {
      slotName = "'" + ast.name + "'";
    }
-
-    let scope = null;
+    const dynProps = ast.attrs ? ast.attrs["t-props"] : null;
    if (ast.attrs) {
-      const params = [];
-      for (const [n, v] of Object.entries(ast.attrs!)) {
-        params.push(`${n}: ${compileExpr(v) || undefined}`);
-      }
-      scope = `{${params.join(", ")}}`;
+      delete ast.attrs["t-props"];
    }
-
+    const props = ast.attrs ? this.formatPropObject(ast.attrs) : [];
+    const scope = this.getPropString(props, dynProps);
    if (ast.defaultContent) {
      const name = this.compileInNewTarget("defaultContent", ast.defaultContent, ctx);
      blockString = `callSlot(ctx, node, key, ${slotName}, ${dynamic}, ${scope}, ${name})`;
    } else {
      if (dynamic) {
-        let name = this.generateId("slot");
-        this.addLine(`const ${name} = ${slotName};`);
-        blockString = `toggler(${name}, callSlot(ctx, node, key, ${name}), ${dynamic}, ${scope})`;
+        let name = generateId("slot");
+        this.define(name, slotName);
+        blockString = `toggler(${name}, callSlot(ctx, node, key, ${name}, ${dynamic}, ${scope}))`;
      } else {
        blockString = `callSlot(ctx, node, key, ${slotName}, ${dynamic}, ${scope})`;
      }
    }
+    // event handling
+    if (ast.on) {
+      blockString = this.wrapWithEventCatcher(blockString, ast.on);
+    }
+
    if (block) {
      this.insertAnchor(block);
    }
@@ -1188,18 +1257,21 @@ export class CodeGenerator {
    }
  }
  compileTPortal(ast: ASTTPortal, ctx: Context) {
-    this.helpers.add("Portal");
+    if (!this.staticDefs.find((d) => d.id === "Portal")) {
+      this.staticDefs.push({ id: "Portal", expr: `app.Portal` });
+    }

    let { block } = ctx;
    const name = this.compileInNewTarget("slot", ast.content, ctx);
    const key = this.generateComponentKey();
    let ctxStr = "ctx";
    if (this.target.loopLevel || !this.hasSafeContext) {
-      ctxStr = this.generateId("ctx");
+      ctxStr = generateId("ctx");
      this.helpers.add("capture");
-      this.addLine(`const ${ctxStr} = capture(ctx);`);
+      this.define(ctxStr, `capture(ctx);`);
    }
-    const blockString = `component(Portal, {target: ${ast.target},slots: {'default': {__render: ${name}, __ctx: ${ctxStr}}}}, key + \`${key}\`, node, ctx)`;
+    const target = compileExpr(ast.target);
+    const blockString = `component(Portal, {target: ${target},slots: {'default': {__render: ${name}, __ctx: ${ctxStr}}}}, key + \`${key}\`, node, ctx)`;
    if (block) {
      this.insertAnchor(block);
    }
@@ -1,16 +1,19 @@
-import type { BDom } from "../blockdom";
+import type { TemplateSet } from "../runtime/template_set";
+import type { BDom } from "../runtime/blockdom";
 import { CodeGenerator, Config } from "./code_generator";
 import { parse } from "./parser";

 export type Template = (context: any, vnode: any, key?: string) => BDom;

-export type TemplateFunction = (blocks: any, utils: any) => Template;
+export type TemplateFunction = (app: TemplateSet, bdom: any, helpers: any) => Template;

 interface CompileOptions extends Config {
  name?: string;
-  nameSpace?: string,
 }
-export function compile(template: string | Node, options: CompileOptions = {}): TemplateFunction {
+export function compile(
+  template: string | Element,
+  options: CompileOptions = {}
+): TemplateFunction {
  // parsing
  const ast = parse(template);

@@ -21,10 +24,8 @@ export function compile(template: string | Node, options: CompileOptions = {}):
      : !template.includes("t-set") && !template.includes("t-call");

  // code generation
-  console.log("compile", options)
  const codeGenerator = new CodeGenerator(ast, { ...options, hasSafeContext });
  const code = codeGenerator.generateCode();
-  console.log(code)
  // template function
-  return new Function("bdom, helpers", code) as TemplateFunction;
+  return new Function("app, bdom, helpers", code) as TemplateFunction;
 }
@@ -85,8 +85,10 @@ const STATIC_TOKEN_MAP: { [key: string]: TKind } = Object.assign(Object.create(n
 });

 // note that the space after typeof is relevant. It makes sure that the formatted
-// expression has a space after typeof
-const OPERATORS = "...,.,===,==,+,!==,!=,!,||,&&,>=,>,<=,<,?,-,*,/,%,typeof ,=>,=,;,in ".split(",");
+// expression has a space after typeof. Currently we don't support delete and void
+const OPERATORS = "...,.,===,==,+,!==,!=,!,||,&&,>=,>,<=,<,?,-,*,/,%,typeof ,=>,=,;,in ,new ".split(
+  ","
+);

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

@@ -199,24 +201,30 @@ const TOKENIZERS = [
 export function tokenize(expr: string): Token[] {
  const result: Token[] = [];
  let token: boolean | Token = true;
+  let error: any;
+  let current = expr;

-  while (token) {
-    expr = expr.trim();
-    if (expr) {
-      for (let tokenizer of TOKENIZERS) {
-        token = tokenizer(expr);
-        if (token) {
-          result.push(token);
-          expr = expr.slice(token.size || token.value.length);
-          break;
+  try {
+    while (token) {
+      current = current.trim();
+      if (current) {
+        for (let tokenizer of TOKENIZERS) {
+          token = tokenizer(current);
+          if (token) {
+            result.push(token);
+            current = current.slice(token.size || token.value.length);
+            break;
+          }
        }
+      } else {
+        token = false;
      }
-    } else {
-      token = false;
    }
+  } catch (e) {
+    error = e; // Silence all errors and throw a generic error below
  }
-  if (expr.length) {
-    throw new Error(`Tokenizer error: could not tokenize "${expr}"`);
+  if (current.length || error) {
+    throw new Error(`Tokenizer error: could not tokenize \`${expr}\``);
  }
  return result;
 }
@@ -329,28 +337,38 @@ export function compileExprToArray(expr: string): Token[] {
  // Mark all variables that have been used locally.
  // This assumes the expression has only one scope (incorrect but "good enough for now")
  for (const token of tokens) {
-    if (token.type === "SYMBOL" && localVars.has(token.value)) {
+    if (token.type === "SYMBOL" && token.varName && localVars.has(token.value)) {
+      token.originalValue = token.value;
+      token.value = `_${token.value}`;
      token.isLocal = true;
    }
  }
  return tokens;
 }

+// Leading spaces are trimmed during tokenization, so they need to be added back for some values
+const paddedValues = new Map([["in ", " in "]]);
+
 export function compileExpr(expr: string): string {
  return compileExprToArray(expr)
-    .map((t) => t.value)
+    .map((t) => paddedValues.get(t.value) || t.value)
    .join("");
 }

-export const INTERP_REGEXP = /\{\{.*?\}\}/g;
-const INTERP_GROUP_REGEXP = /\{\{.*?\}\}/g;
+export const INTERP_REGEXP = /\{\{.*?\}\}|\#\{.*?\}/g;

-export function interpolate(s: string): string {
+export function replaceDynamicParts(s: string, replacer: (s: string) => string) {
  let matches = s.match(INTERP_REGEXP);
  if (matches && matches[0].length === s.length) {
-    return `(${compileExpr(s.slice(2, -2))})`;
+    return `(${replacer(s.slice(2, matches[0][0] === "{" ? -2 : -1))})`;
  }

-  let r = s.replace(INTERP_GROUP_REGEXP, (s) => "${" + compileExpr(s.slice(2, -2)) + "}");
+  let r = s.replace(
+    INTERP_REGEXP,
+    (s) => "${" + replacer(s.slice(2, s[0] === "{" ? -2 : -1)) + "}"
+  );
  return "`" + r + "`";
 }
+export function interpolate(s: string): string {
+  return replaceDynamicParts(s, compileExpr);
+}
@@ -2,6 +2,9 @@
 // AST Type definition
 // -----------------------------------------------------------------------------

+export type EventHandlers = { [eventName: string]: string };
+export type Attrs = { [attrs: string]: string };
+
 export const enum ASTType {
  Text,
  Comment,
@@ -33,23 +36,26 @@ export interface ASTComment {
  value: string;
 }

+interface TModelInfo {
+  baseExpr: string;
+  expr: string;
+  targetAttr: string;
+  eventType: "change" | "click" | "input";
+  shouldTrim: boolean;
+  shouldNumberize: boolean;
+  hasDynamicChildren: boolean;
+  specialInitTargetAttr: string | null;
+}
+
 export interface ASTDomNode {
  type: ASTType.DomNode;
  tag: string;
-  dynamicTag: string | null;
-  attrs: { [key: string]: string };
  content: AST[];
+  attrs: Attrs | null;
  ref: string | null;
-  on: { [key: string]: string };
-  model: {
-    baseExpr: string;
-    expr: string;
-    targetAttr: string;
-    specialInitTargetAttr: string | null;
-    eventType: "change" | "click" | "input";
-    shouldTrim: boolean;
-    shouldNumberize: boolean;
-  } | null;
+  on: EventHandlers | null;
+  model: TModelInfo | null;
+  dynamicTag: string | null;
  ns: string | null;
 }

@@ -90,13 +96,13 @@ export interface ASTTForEach {
  type: ASTType.TForEach;
  collection: string;
  elem: string;
-  key: string | null;
  body: AST;
  memo: string;
  hasNoFirst: boolean;
  hasNoLast: boolean;
  hasNoIndex: boolean;
  hasNoValue: boolean;
+  key: string | null;
 }

 export interface ASTTKey {
@@ -111,19 +117,28 @@ export interface ASTTCall {
  body: AST[] | null;
 }

+interface SlotDefinition {
+  content: AST | null;
+  scope: string | null;
+  on: EventHandlers | null;
+  attrs: Attrs | null;
+}
+
 export interface ASTComponent {
  type: ASTType.TComponent;
  name: string;
  isDynamic: boolean;
  dynamicProps: string | null;
-  props: { [name: string]: string };
-  slots: { [name: string]: { content: AST; attrs?: { [key: string]: string }; scope?: string } };
+  on: EventHandlers | null;
+  props: { [name: string]: string } | null;
+  slots: { [name: string]: SlotDefinition } | null;
 }

 export interface ASTSlot {
  type: ASTType.TSlot;
  name: string;
-  attrs: { [key: string]: string };
+  attrs: Attrs | null;
+  on: EventHandlers | null;
  defaultContent: AST | null;
 }

@@ -177,23 +192,35 @@ export type AST =
 // -----------------------------------------------------------------------------
 // Parser
 // -----------------------------------------------------------------------------
-interface ParsingContext {
-  inPreTag: boolean;
-  inSVG: boolean;
-}
+const cache: WeakMap<Element, AST> = new WeakMap();

-export function parse(xml: string | Node): AST {
-  const node = xml instanceof Element ? xml : (parseXML(`<t>${xml}</t>`).firstChild! as Element);
-  normalizeXML(node);
-  const ctx = { inPreTag: false, inSVG: false };
-  const ast = parseNode(node, ctx);
+export function parse(xml: string | Element): AST {
+  if (typeof xml === "string") {
+    const elem = parseXML(`<t>${xml}</t>`).firstChild as Element;
+    return _parse(elem);
+  }
+  let ast = cache.get(xml);
  if (!ast) {
-    return { type: ASTType.Text, value: "" };
+    // we clone here the xml to prevent modifying it in place
+    ast = _parse(xml.cloneNode(true) as Element);
+    cache.set(xml, ast);
  }
  return ast;
 }

-function parseNode(node: ChildNode, ctx: ParsingContext): AST | null {
+function _parse(xml: Element): AST {
+  normalizeXML(xml);
+  const ctx = { inPreTag: false, inSVG: false };
+  return parseNode(xml, ctx) || { type: ASTType.Text, value: "" };
+}
+
+interface ParsingContext {
+  tModelInfo?: TModelInfo | null;
+  inPreTag: boolean;
+  inSVG: boolean;
+}
+
+function parseNode(node: Node, ctx: ParsingContext): AST | null {
  if (!(node instanceof Element)) {
    return parseTextCommentNode(node, ctx);
  }
@@ -233,7 +260,7 @@ function parseTNode(node: Element, ctx: ParsingContext): AST | null {
 const lineBreakRE = /[\r\n]/;
 const whitespaceRE = /\s+/g;

-function parseTextCommentNode(node: ChildNode, ctx: ParsingContext): AST | null {
+function parseTextCommentNode(node: Node, ctx: ParsingContext): AST | null {
  if (node.nodeType === Node.TEXT_NODE) {
    let value = node.textContent || "";
    if (!ctx.inPreTag) {
@@ -281,6 +308,8 @@ function parseTDebugLog(node: Element, ctx: ParsingContext): AST | null {
 const hasDotAtTheEnd = /\.[\w_]+\s*$/;
 const hasBracketsAtTheEnd = /\[[^\[]+\]\s*$/;

+const ROOT_SVG_TAGS = new Set(["svg", "g", "path"]);
+
 function parseDOMNode(node: Element, ctx: ParsingContext): AST | null {
  const { tagName } = node;
  const dynamicTag = node.getAttribute("t-tag");
@@ -288,22 +317,23 @@ function parseDOMNode(node: Element, ctx: ParsingContext): AST | null {
  if (tagName === "t" && !dynamicTag) {
    return null;
  }
+  if (tagName.startsWith("block-")) {
+    throw new Error(`Invalid tag name: '${tagName}'`);
+  }
  ctx = Object.assign({}, ctx);
  if (tagName === "pre") {
    ctx.inPreTag = true;
  }
-  const shouldAddSVGNS = tagName === "svg" || (tagName === "g" && !ctx.inSVG);
+  const shouldAddSVGNS = ROOT_SVG_TAGS.has(tagName) && !ctx.inSVG;
  ctx.inSVG = ctx.inSVG || shouldAddSVGNS;
  const ns = shouldAddSVGNS ? "http://www.w3.org/2000/svg" : null;
  const ref = node.getAttribute("t-ref");
  node.removeAttribute("t-ref");

-  const children = parseChildren(node, ctx);
-
  const nodeAttrsNames = node.getAttributeNames();
-  const attrs: ASTDomNode["attrs"] = {};
-  const on: ASTDomNode["on"] = {};
-  let model: ASTDomNode["model"] = null;
+  let attrs: ASTDomNode["attrs"] = null;
+  let on: EventHandlers | null = null;
+  let model: TModelInfo | null = null;

  for (let attr of nodeAttrsNames) {
    const value = node.getAttribute(attr)!;
@@ -311,6 +341,7 @@ function parseDOMNode(node: Element, ctx: ParsingContext): AST | null {
      if (attr === "t-on") {
        throw new Error("Missing event name with t-on directive");
      }
+      on = on || {};
      on[attr.slice(5)] = value;
    } else if (attr.startsWith("t-model")) {
      if (!["input", "select", "textarea"].includes(tagName)) {
@@ -348,16 +379,31 @@ function parseDOMNode(node: Element, ctx: ParsingContext): AST | null {
        targetAttr: isCheckboxInput ? "checked" : "value",
        specialInitTargetAttr: isRadioInput ? "checked" : null,
        eventType,
+        hasDynamicChildren: false,
        shouldTrim: hasTrimMod && (isOtherInput || isTextarea),
        shouldNumberize: hasNumberMod && (isOtherInput || isTextarea),
      };
-    } else {
+      if (isSelect) {
+        // don't pollute the original ctx
+        ctx = Object.assign({}, ctx);
+        ctx.tModelInfo = model;
+      }
+    } else if (attr.startsWith("block-")) {
+      throw new Error(`Invalid attribute: '${attr}'`);
+    } else if (attr !== "t-name") {
      if (attr.startsWith("t-") && !attr.startsWith("t-att")) {
        throw new Error(`Unknown QWeb directive: '${attr}'`);
      }
+      const tModel = ctx.tModelInfo;
+      if (tModel && ["t-att-value", "t-attf-value"].includes(attr)) {
+        tModel.hasDynamicChildren = true;
+      }
+      attrs = attrs || {};
      attrs[attr] = value;
    }
  }
+
+  const children = parseChildren(node, ctx);
  return {
    type: ASTType.DomNode,
    tag: tagName,
@@ -523,7 +569,7 @@ function parseTCall(node: Element, ctx: ParsingContext): AST | null {
    if (ast && ast.type === ASTType.TComponent) {
      return {
        ...ast,
-        slots: { default: { content: tcall } },
+        slots: { default: { content: tcall, scope: null, on: null, attrs: null } },
      };
    }
  }
@@ -619,7 +665,6 @@ function parseTSetNode(node: Element, ctx: ParsingContext): AST | null {

 // Error messages when trying to use an unsupported directive on a component
 const directiveErrorMap = new Map([
-  ["t-on", "t-on is no longer supported on components. Consider passing a callback in props."],
  [
    "t-ref",
    "t-ref is no longer supported on components. Consider exposing only the public part of the component's API through a callback prop.",
@@ -651,18 +696,28 @@ function parseComponent(node: Element, ctx: ParsingContext): AST | null {
  const dynamicProps = node.getAttribute("t-props");
  node.removeAttribute("t-props");

-  const props: ASTComponent["props"] = {};
+  const defaultSlotScope = node.getAttribute("t-slot-scope");
+  node.removeAttribute("t-slot-scope");
+  let on: ASTComponent["on"] = null;
+
+  let props: ASTComponent["props"] = null;
  for (let name of node.getAttributeNames()) {
    const value = node.getAttribute(name)!;
    if (name.startsWith("t-")) {
-      const message = directiveErrorMap.get(name.split("-").slice(0, 2).join("-"));
-      throw new Error(message || `unsupported directive on Component: ${name}`);
+      if (name.startsWith("t-on-")) {
+        on = on || {};
+        on[name.slice(5)] = value;
+      } else {
+        const message = directiveErrorMap.get(name.split("-").slice(0, 2).join("-"));
+        throw new Error(message || `unsupported directive on Component: ${name}`);
+      }
    } else {
+      props = props || {};
      props[name] = value;
    }
  }

-  const slots: ASTComponent["slots"] = {};
+  let slots: ASTComponent["slots"] | null = null;
  if (node.hasChildNodes()) {
    const clone = <Element>node.cloneNode(true);

@@ -694,31 +749,34 @@ function parseComponent(node: Element, ctx: ParsingContext): AST | null {
      slotNode.removeAttribute("t-set-slot");
      slotNode.remove();
      const slotAst = parseNode(slotNode, ctx);
-      if (slotAst) {
-        const slotInfo: any = { content: slotAst };
-        const attrs: { [key: string]: string } = {};
-        for (let attributeName of slotNode.getAttributeNames()) {
-          const value = slotNode.getAttribute(attributeName)!;
-          if (attributeName === "t-slot-scope") {
-            slotInfo.scope = value;
-            continue;
-          }
+      let on: SlotDefinition["on"] = null;
+      let attrs: Attrs | null = null;
+      let scope: string | null = null;
+      for (let attributeName of slotNode.getAttributeNames()) {
+        const value = slotNode.getAttribute(attributeName)!;
+        if (attributeName === "t-slot-scope") {
+          scope = value;
+          continue;
+        } else if (attributeName.startsWith("t-on-")) {
+          on = on || {};
+          on[attributeName.slice(5)] = value;
+        } else {
+          attrs = attrs || {};
          attrs[attributeName] = value;
        }
-        if (Object.keys(attrs).length) {
-          slotInfo.attrs = attrs;
-        }
-        slots[name] = slotInfo;
      }
+      slots = slots || {};
+      slots[name] = { content: slotAst, on, attrs, scope };
    }

    // default slot
    const defaultContent = parseChildNodes(clone, ctx);
    if (defaultContent) {
-      slots.default = { content: defaultContent };
+      slots = slots || {};
+      slots.default = { content: defaultContent, on, attrs: null, scope: defaultSlotScope };
    }
  }
-  return { type: ASTType.TComponent, name, isDynamic, dynamicProps, props, slots };
+  return { type: ASTType.TComponent, name, isDynamic, dynamicProps, props, slots, on };
 }

 // -----------------------------------------------------------------------------
@@ -731,15 +789,23 @@ function parseTSlot(node: Element, ctx: ParsingContext): AST | null {
  }
  const name = node.getAttribute("t-slot")!;
  node.removeAttribute("t-slot");
-  const attrs: { [key: string]: string } = {};
+  let attrs: Attrs | null = null;
+  let on: ASTComponent["on"] = null;
  for (let attributeName of node.getAttributeNames()) {
    const value = node.getAttribute(attributeName)!;
-    attrs[attributeName] = value;
+    if (attributeName.startsWith("t-on-")) {
+      on = on || {};
+      on[attributeName.slice(5)] = value;
+    } else {
+      attrs = attrs || {};
+      attrs[attributeName] = value;
+    }
  }
  return {
    type: ASTType.TSlot,
    name,
    attrs,
+    on,
    defaultContent: parseChildNodes(node, ctx),
  };
 }
@@ -786,7 +852,7 @@ function parseTPortal(node: Element, ctx: ParsingContext): AST | null {
 /**
 * Parse all the child nodes of a given node and return a list of ast elements
 */
-function parseChildren(node: Node, ctx: ParsingContext): AST[] {
+function parseChildren(node: Element, ctx: ParsingContext): AST[] {
  const children: AST[] = [];
  for (let child of node.childNodes) {
    const childAst = parseNode(child, ctx);
@@ -805,7 +871,7 @@ function parseChildren(node: Node, ctx: ParsingContext): AST[] {
 * Parse all the child nodes of a given node and return an ast if possible.
 * In the case there are multiple children, they are wrapped in a astmulti.
 */
-function parseChildNodes(node: Node, ctx: ParsingContext): AST | null {
+function parseChildNodes(node: Element, ctx: ParsingContext): AST | null {
  const children = parseChildren(node, ctx);
  switch (children.length) {
    case 0:
@@ -1,71 +0,0 @@
-import { getCurrent } from "./component_node";
-import { nodeErrorHandlers } from "./error_handling";
-
-// -----------------------------------------------------------------------------
-//  hooks
-// -----------------------------------------------------------------------------
-
-export function onWillStart(fn: () => Promise<void> | void | any) {
-  const node = getCurrent()!;
-  node.willStart.push(fn.bind(node.component));
-}
-
-export function onWillUpdateProps(fn: (nextProps: any) => Promise<void> | void | any) {
-  const node = getCurrent()!;
-  node.willUpdateProps.push(fn.bind(node.component));
-}
-
-export function onMounted(fn: () => void | any) {
-  const node = getCurrent()!;
-  node.mounted.push(fn.bind(node.component));
-}
-
-export function onWillPatch(fn: () => Promise<void> | any | void) {
-  const node = getCurrent()!;
-  node.willPatch.unshift(fn.bind(node.component));
-}
-
-export function onPatched(fn: () => void | any) {
-  const node = getCurrent()!;
-  node.patched.push(fn.bind(node.component));
-}
-
-export function onWillUnmount(fn: () => Promise<void> | void | any) {
-  const node = getCurrent()!;
-  node.willUnmount.unshift(fn.bind(node.component));
-}
-
-export function onWillDestroy(fn: () => Promise<void> | void | any) {
-  const node = getCurrent()!;
-  node.willDestroy.push(fn.bind(node.component));
-}
-
-export function onWillRender(fn: () => void | any) {
-  const node = getCurrent()!;
-  const renderFn = node.renderFn;
-  node.renderFn = () => {
-    fn.call(node.component);
-    return renderFn();
-  };
-}
-
-export function onRendered(fn: () => void | any) {
-  const node = getCurrent()!;
-  const renderFn = node.renderFn;
-  node.renderFn = () => {
-    const result = renderFn();
-    fn.call(node.component);
-    return result;
-  };
-}
-
-type OnErrorCallback = (error: any) => void | any;
-export function onError(callback: OnErrorCallback) {
-  const node = getCurrent()!;
-  let handlers = nodeErrorHandlers.get(node);
-  if (!handlers) {
-    handlers = [];
-    nodeErrorHandlers.set(node, handlers);
-  }
-  handlers.push(callback.bind(node.component));
-}
@@ -1,133 +0,0 @@
-import { Component } from "./component";
-
-/**
- * Apply default props (only top level).
- *
- * Note that this method does modify in place the props
- */
-export function applyDefaultProps(props: { [key: string]: any }, ComponentClass: typeof Component) {
-  const defaultProps = (ComponentClass as any).defaultProps;
-  if (defaultProps) {
-    for (let propName in defaultProps) {
-      if (props![propName] === undefined) {
-        props![propName] = defaultProps[propName];
-      }
-    }
-  }
-}
-
-//------------------------------------------------------------------------------
-// Prop validation helper
-//------------------------------------------------------------------------------
-function getPropDescription(staticProps: any) {
-  if (staticProps instanceof Array) {
-    return Object.fromEntries(
-      staticProps.map((p) => (p.endsWith("?") ? [p.slice(0, -1), false] : [p, true]))
-    );
-  }
-  return staticProps || { "*": true };
-}
-
-/**
- * Validate the component props (or next props) against the (static) props
- * description.  This is potentially an expensive operation: it may needs to
- * visit recursively the props and all the children to check if they are valid.
- * This is why it is only done in 'dev' mode.
- */
-export const validateProps = function (name: string | typeof Component, props: any, parent?: any) {
-  const ComponentClass = (
-    typeof name !== "string" ? name : parent.constructor.components[name]
-  ) as typeof Component;
-
-  applyDefaultProps(props, ComponentClass);
-
-  let propsDef = getPropDescription(ComponentClass.props);
-  const allowAdditionalProps = "*" in propsDef;
-
-  for (let propName in propsDef) {
-    if (propName === "*") {
-      continue;
-    }
-    if (props[propName] === undefined) {
-      if (propsDef[propName] && !propsDef[propName].optional) {
-        throw new Error(`Missing props '${propName}' (component '${ComponentClass.name}')`);
-      } else {
-        continue;
-      }
-    }
-    let isValid;
-    try {
-      isValid = isValidProp(props[propName], propsDef[propName]);
-    } catch (e) {
-      (e as Error).message = `Invalid prop '${propName}' in component ${ComponentClass.name} (${
-        (e as Error).message
-      })`;
-      throw e;
-    }
-    if (!isValid) {
-      throw new Error(`Invalid Prop '${propName}' in component '${ComponentClass.name}'`);
-    }
-  }
-  if (!allowAdditionalProps) {
-    for (let propName in props) {
-      if (!(propName in propsDef)) {
-        throw new Error(`Unknown prop '${propName}' given to component '${ComponentClass.name}'`);
-      }
-    }
-  }
-};
-
-/**
- * Check if an invidual prop value matches its (static) prop definition
- */
-function isValidProp(prop: any, propDef: any): boolean {
-  if (propDef === true) {
-    return true;
-  }
-  if (typeof propDef === "function") {
-    // Check if a value is constructed by some Constructor.  Note that there is a
-    // slight abuse of language: we want to consider primitive values as well.
-    //
-    // So, even though 1 is not an instance of Number, we want to consider that
-    // it is valid.
-    if (typeof prop === "object") {
-      return prop instanceof propDef;
-    }
-    return typeof prop === propDef.name.toLowerCase();
-  } else if (propDef instanceof Array) {
-    // If this code is executed, this means that we want to check if a prop
-    // matches at least one of its descriptor.
-    let result = false;
-    for (let i = 0, iLen = propDef.length; i < iLen; i++) {
-      result = result || isValidProp(prop, propDef[i]);
-    }
-    return result;
-  }
-  // propsDef is an object
-  if (propDef.optional && prop === undefined) {
-    return true;
-  }
-  let result = propDef.type ? isValidProp(prop, propDef.type) : true;
-  if (propDef.validate) {
-    result = result && propDef.validate(prop);
-  }
-  if (propDef.type === Array && propDef.element) {
-    for (let i = 0, iLen = prop.length; i < iLen; i++) {
-      result = result && isValidProp(prop[i], propDef.element);
-    }
-  }
-  if (propDef.type === Object && propDef.shape) {
-    const shape = propDef.shape;
-    for (let key in shape) {
-      result = result && isValidProp(prop[key], shape[key]);
-    }
-    if (result) {
-      for (let propName in prop) {
-        if (!(propName in shape)) {
-          throw new Error(`unknown prop '${propName}'`);
-        }
-      }
-    }
-  }
-  return result;
-}
@@ -1,77 +0,0 @@
-import { fibersInError } from "./error_handling";
-import { Fiber, RootFiber } from "./fibers";
-import { STATUS } from "./status";
-
-// -----------------------------------------------------------------------------
-//  Scheduler
-// -----------------------------------------------------------------------------
-
-export class Scheduler {
-  // capture the value of requestAnimationFrame as soon as possible, to avoid
-  // interactions with other code, such as test frameworks that override them
-  static requestAnimationFrame = window.requestAnimationFrame.bind(window);
-  tasks: Set<RootFiber> = new Set();
-  isRunning: boolean = false;
-  requestAnimationFrame: Window["requestAnimationFrame"];
-
-  constructor() {
-    this.requestAnimationFrame = Scheduler.requestAnimationFrame;
-  }
-
-  start() {
-    this.isRunning = true;
-    this.scheduleTasks();
-  }
-
-  stop() {
-    this.isRunning = false;
-  }
-
-  addFiber(fiber: Fiber) {
-    this.tasks.add(fiber.root!);
-    if (!this.isRunning) {
-      this.start();
-    }
-  }
-
-  /**
-   * Process all current tasks. This only applies to the fibers that are ready.
-   * Other tasks are left unchanged.
-   */
-  flush() {
-    this.tasks.forEach((fiber) => {
-      if (fiber.root !== fiber) {
-        this.tasks.delete(fiber);
-        return;
-      }
-      const hasError = fibersInError.has(fiber);
-      if (hasError && fiber.counter !== 0) {
-        this.tasks.delete(fiber);
-        return;
-      }
-      if (fiber.node.status === STATUS.DESTROYED) {
-        this.tasks.delete(fiber);
-        return;
-      }
-
-      if (fiber.counter === 0) {
-        if (!hasError) {
-          fiber.complete();
-        }
-        this.tasks.delete(fiber);
-      }
-    });
-    if (this.tasks.size === 0) {
-      this.stop();
-    }
-  }
-
-  scheduleTasks() {
-    this.requestAnimationFrame(() => {
-      this.flush();
-      if (this.isRunning) {
-        this.scheduleTasks();
-      }
-    });
-  }
-}
@@ -1,61 +1,16 @@
-import { UTILS } from "./app/template_helpers";
-import {
-  config,
-  createBlock,
-  html,
-  list,
-  mount as blockMount,
-  multi,
-  patch,
-  remove,
-  text,
-  toggler,
-  comment,
-} from "./blockdom";
-import { mainEventHandler } from "./component/handler";
-import { Portal } from "./portal";
-export type { Reactive } from "./reactivity";
+import { TemplateSet } from "./runtime/template_set";
+import { compile } from "./compiler";

-config.shouldNormalizeDom = false;
-config.mainEventHandler = mainEventHandler;
-(UTILS as any).Portal = Portal;
+export * from "./runtime";

-export const blockDom = {
-  config,
-  // bdom entry points
-  mount: blockMount,
-  patch,
-  remove,
-  // bdom block types
-  list,
-  multi,
-  text,
-  toggler,
-  createBlock,
-  html,
-  comment,
+TemplateSet.prototype._compileTemplate = function _compileTemplate(
+  name: string,
+  template: string | Element
+) {
+  return compile(template, {
+    name,
+    dev: this.dev,
+    translateFn: this.translateFn,
+    translatableAttributes: this.translatableAttributes,
+  });
 };
-
-export { App, mount } from "./app/app";
-export { Component } from "./component/component";
-export { useComponent } from "./component/component_node";
-export { status } from "./component/status";
-export { Memo } from "./memo";
-export { xml } from "./app/template_set";
-export { useState, reactive } from "./reactivity";
-export { useEffect, useEnv, useExternalListener, useRef, useSubEnv } from "./hooks";
-export { EventBus, whenReady, loadFile, markup } from "./utils";
-export {
-  onWillStart,
-  onMounted,
-  onWillUnmount,
-  onWillUpdateProps,
-  onWillPatch,
-  onPatched,
-  onWillRender,
-  onRendered,
-  onWillDestroy,
-  onError,
-} from "./component/lifecycle_hooks";
-
-export const __info__ = {};
@@ -1,47 +0,0 @@
-import { Component } from "./component/component";
-import type { ComponentNode } from "./component/component_node";
-import { xml } from "./app/template_set";
-import { Fiber } from "./component/fibers";
-
-export class Memo extends Component {
-  static template = xml`<t t-slot="default"/>`;
-
-  constructor(props: any, env: any, node: ComponentNode) {
-    super(props, env, node);
-
-    // prevent patching process conditionally
-    let applyPatch = false;
-    const patchFn = node.patch;
-    node.patch = () => {
-      if (applyPatch) {
-        patchFn.call(node);
-        applyPatch = false;
-      }
-    };
-
-    // check props change, and render/apply patch if it changed
-    let prevProps = props;
-    const updateAndRender = node.updateAndRender;
-    node.updateAndRender = function (props: any, parentFiber: Fiber) {
-      const shouldUpdate = !shallowEqual(prevProps, props);
-      if (shouldUpdate) {
-        prevProps = props;
-        updateAndRender.call(node, props, parentFiber);
-        applyPatch = true;
-      }
-      return Promise.resolve();
-    };
-  }
-}
-
-/**
- * we assume that each object have the same set of keys
- */
-function shallowEqual(p1: any, p2: any): boolean {
-  for (let k in p1) {
-    if (k !== "slots" && p1[k] !== p2[k]) {
-      return false;
-    }
-  }
-  return true;
-}
@@ -1,217 +0,0 @@
-import { onWillUnmount } from "./component/lifecycle_hooks";
-import { ComponentNode, getCurrent } from "./component/component_node";
-import { batched, Callback } from "./utils";
-
-// Allows to get the target of a Reactive (used for making a new Reactive from the underlying object)
-const TARGET = Symbol("Target");
-// Special key to subscribe to, to be notified of key creation/deletion
-const KEYCHANGES = Symbol("Key changes");
-
-type ObjectKey = string | number | symbol;
-type Target = object;
-export type Reactive<T extends Target = Target> = T & {
-  [TARGET]: any;
-};
-
-/**
- * Checks whether a given value can be made into a reactive object.
- *
- * @param value the value to check
- * @returns whether the value can be made reactive
- */
-function canBeMadeReactive(value: any): boolean {
-  return (
-    typeof value === "object" &&
-    value !== null &&
-    !(value instanceof Date) &&
-    !(value instanceof Promise) &&
-    !(value instanceof String) &&
-    !(value instanceof Number)
-  );
-}
-
-const targetToKeysToCallbacks = new WeakMap<Target, Map<ObjectKey, Set<Callback>>>();
-/**
- * Observes a given key on a target with an callback. The callback will be
- * called when the given key changes on the target.
- *
- * @param target the target whose key should be observed
- * @param key the key to observe (or Symbol(KEYCHANGES) for key creation
- *  or deletion)
- * @param callback the function to call when the key changes
- */
-function observeTargetKey(target: Target, key: ObjectKey, callback: Callback): void {
-  if (!targetToKeysToCallbacks.get(target)) {
-    targetToKeysToCallbacks.set(target, new Map());
-  }
-  const keyToCallbacks = targetToKeysToCallbacks.get(target)!;
-  if (!keyToCallbacks.get(key)) {
-    keyToCallbacks.set(key, new Set());
-  }
-  keyToCallbacks.get(key)!.add(callback);
-  if (!callbacksToTargets.has(callback)) {
-    callbacksToTargets.set(callback, new Set());
-  }
-  callbacksToTargets.get(callback)!.add(target);
-}
-/**
- * Notify Reactives that are observing a given target that a key has changed on
- * the target.
- *
- * @param target target whose Reactives should be notified that the target was
- *  changed.
- * @param key the key that changed (or Symbol `KEYCHANGES` if a key was created
- *   or deleted)
- */
-function notifyReactives(target: Target, key: ObjectKey): void {
-  const keyToCallbacks = targetToKeysToCallbacks.get(target);
-  if (!keyToCallbacks) {
-    return;
-  }
-  const callbacks = keyToCallbacks.get(key);
-  if (!callbacks) {
-    return;
-  }
-  // Loop on copy because clearReactivesForCallback will modify the set in place
-  for (const callback of [...callbacks]) {
-    clearReactivesForCallback(callback);
-    callback();
-  }
-}
-
-const callbacksToTargets = new WeakMap<Callback, Set<Target>>();
-/**
- * Clears all subscriptions of the Reactives associated with a given callback.
- *
- * @param callback the callback for which the reactives need to be cleared
- */
-function clearReactivesForCallback(callback: Callback): void {
-  const targetsToClear = callbacksToTargets.get(callback);
-  if (!targetsToClear) {
-    return;
-  }
-  for (const target of targetsToClear) {
-    const observedKeys = targetToKeysToCallbacks.get(target);
-    if (!observedKeys) {
-      continue;
-    }
-    for (const callbacks of observedKeys.values()) {
-      callbacks.delete(callback);
-    }
-  }
-  targetsToClear.clear();
-}
-
-const reactiveCache = new WeakMap<Target, WeakMap<Callback, Reactive>>();
-/**
- * Creates a reactive proxy for an object. Reading data on the reactive object
- * subscribes to changes to the data. Writing data on the object will cause the
- * notify callback to be called if there are suscriptions to that data. Nested
- * objects and arrays are automatically made reactive as well.
- *
- * Whenever you are notified of a change, all subscriptions are cleared, and if
- * you would like to be notified of any further changes, you should go read
- * the underlying data again. We assume that if you don't go read it again after
- * being notified, it means that you are no longer interested in that data.
- *
- * Subscriptions:
- * + Reading a property on an object will subscribe you to changes in the value
- *    of that property.
- * + Accessing an object keys (eg with Object.keys or with `for..in`) will
- *    subscribe you to the creation/deletion of keys. Checking the presence of a
- *    key on the object with 'in' has the same effect.
- * - getOwnPropertyDescriptor does not currently subscribe you to the property.
- *    This is a choice that was made because changing a key's value will trigger
- *    this trap and we do not want to subscribe by writes. This also means that
- *    Object.hasOwnProperty doesn't subscribe as it goes through this trap.
- *
- * @param target the object for which to create a reactive proxy
- * @param callback the function to call when an observed property of the
- *  reactive has changed
- * @returns a proxy that tracks changes to it
- */
-export function reactive<T extends Target>(target: T, callback: Callback = () => {}): Reactive<T> {
-  if (!canBeMadeReactive(target)) {
-    throw new Error(`Cannot make the given value reactive`);
-  }
-  const originalTarget = (target as Reactive)[TARGET];
-  if (originalTarget) {
-    return reactive(originalTarget, callback);
-  }
-  if (!reactiveCache.has(target)) {
-    reactiveCache.set(target, new Map());
-  }
-  const reactivesForTarget = reactiveCache.get(target)!;
-  if (!reactivesForTarget.has(callback)) {
-    const proxy = new Proxy(target, {
-      get(target: any, key: ObjectKey, proxy: Reactive<T>) {
-        if (key === TARGET) {
-          return target;
-        }
-        observeTargetKey(target, key, callback);
-        const value = Reflect.get(target, key, proxy);
-        if (!canBeMadeReactive(value)) {
-          return value;
-        }
-        return reactive(value, callback);
-      },
-      set(target, key, value, proxy) {
-        const isNewKey = !Object.hasOwnProperty.call(target, key);
-        const originalValue = Reflect.get(target, key, proxy);
-        const ret = Reflect.set(target, key, value, proxy);
-        if (isNewKey) {
-          notifyReactives(target, KEYCHANGES);
-        }
-        // While Array length may trigger the set trap, it's not actually set by this
-        // method but is updated behind the scenes, and the trap is not called with the
-        // new value. We disable the "same-value-optimization" for it because of that.
-        if (originalValue !== value || (Array.isArray(target) && key === "length")) {
-          notifyReactives(target, key);
-        }
-        return ret;
-      },
-      deleteProperty(target, key) {
-        const ret = Reflect.deleteProperty(target, key);
-        notifyReactives(target, KEYCHANGES);
-        notifyReactives(target, key);
-        return ret;
-      },
-      ownKeys(target) {
-        observeTargetKey(target, KEYCHANGES, callback);
-        return Reflect.ownKeys(target);
-      },
-      has(target, key) {
-        // TODO: this observes all key changes instead of only the presence of the argument key
-        observeTargetKey(target, KEYCHANGES, callback);
-        return Reflect.has(target, key);
-      },
-    });
-    reactivesForTarget.set(callback, proxy);
-  }
-  return reactivesForTarget.get(callback) as Reactive<T>;
-}
-
-const batchedRenderFunctions = new WeakMap<ComponentNode, Callback>();
-/**
- * Creates a reactive object that will be observed by the current component.
- * Reading data from the returned object (eg during rendering) will cause the
- * component to subscribe to that data and be rerendered when it changes.
- *
- * @param state the state to observe
- * @returns a reactive object that will cause the component to re-render on
- *  relevant changes
- * @see reactive
- */
-export function useState<T extends object>(state: T): Reactive<T> {
-  const node = getCurrent()!;
-  if (!batchedRenderFunctions.has(node)) {
-    batchedRenderFunctions.set(
-      node,
-      batched(() => node.render())
-    );
-    onWillUnmount(() => clearReactivesForCallback(render));
-  }
-  const render = batchedRenderFunctions.get(node)!;
-  const reactiveState = reactive(state, render);
-  return reactiveState;
-}
@@ -0,0 +1,127 @@
+import { Component, ComponentConstructor } from "./component";
+import { ComponentNode } from "./component_node";
+import { MountOptions } from "./fibers";
+import { Scheduler } from "./scheduler";
+import { TemplateSet, TemplateSetConfig } from "./template_set";
+import { nodeErrorHandlers } from "./error_handling";
+import { validateTarget } from "./utils";
+import { validateProps } from "./template_helpers";
+
+// reimplement dev mode stuff see last change in 0f7a8289a6fb8387c3c1af41c6664b2a8448758f
+
+export interface Env {
+  [key: string]: any;
+}
+
+export interface AppConfig<P, E> extends TemplateSetConfig {
+  props?: P;
+  env?: E;
+  test?: boolean;
+  warnIfNoStaticProps?: boolean;
+}
+
+let hasBeenLogged = false;
+
+export const DEV_MSG = () => {
+  const hash = (window as any).owl ? (window as any).owl.__info__.hash : "master";
+
+  return `Owl is running in 'dev' mode.
+
+This is not suitable for production use.
+See https://github.com/odoo/owl/blob/${hash}/doc/reference/app.md#configuration for more information.`;
+};
+
+export class App<
+  T extends abstract new (...args: any) => any = any,
+  P extends object = any,
+  E = any
+> extends TemplateSet {
+  static validateTarget = validateTarget;
+
+  Root: ComponentConstructor<P, E>;
+  props: P;
+  env: E;
+  scheduler = new Scheduler();
+  root: ComponentNode<P, E> | null = null;
+  warnIfNoStaticProps: boolean;
+
+  constructor(Root: ComponentConstructor<P, E>, config: AppConfig<P, E> = {}) {
+    super(config);
+    this.Root = Root;
+    if (config.test) {
+      this.dev = true;
+    }
+    this.warnIfNoStaticProps = config.warnIfNoStaticProps || false;
+    if (this.dev && !config.test && !hasBeenLogged) {
+      console.info(DEV_MSG());
+      hasBeenLogged = true;
+    }
+    const env = config.env || {};
+    const descrs = Object.getOwnPropertyDescriptors(env);
+    this.env = Object.freeze(Object.create(Object.getPrototypeOf(env), descrs));
+    this.props = config.props || ({} as P);
+  }
+
+  mount(target: HTMLElement, options?: MountOptions): Promise<Component<P, E> & InstanceType<T>> {
+    App.validateTarget(target);
+    if (this.dev) {
+      validateProps(this.Root, this.props, { __owl__: { app: this } });
+    }
+    const node = this.makeNode(this.Root, this.props);
+    const prom = this.mountNode(node, target, options);
+    this.root = node;
+    return prom;
+  }
+
+  makeNode(Component: ComponentConstructor, props: any): ComponentNode {
+    return new ComponentNode(Component, props, this, null, null);
+  }
+
+  mountNode(node: ComponentNode, target: HTMLElement, options?: MountOptions) {
+    const promise: any = new Promise((resolve, reject) => {
+      let isResolved = false;
+      // manually set a onMounted callback.
+      // that way, we are independant from the current node.
+      node.mounted.push(() => {
+        resolve(node.component);
+        isResolved = true;
+      });
+
+      // Manually add the last resort error handler on the node
+      let handlers = nodeErrorHandlers.get(node);
+      if (!handlers) {
+        handlers = [];
+        nodeErrorHandlers.set(node, handlers);
+      }
+      handlers.unshift((e) => {
+        if (isResolved) {
+          console.error(e);
+        } else {
+          reject(e);
+        }
+        throw e;
+      });
+    });
+    node.mountComponent(target, options);
+    return promise;
+  }
+
+  destroy() {
+    if (this.root) {
+      this.scheduler.flush();
+      this.root.destroy();
+    }
+  }
+}
+
+export async function mount<
+  T extends abstract new (...args: any) => any = any,
+  P extends object = any,
+  E = any
+>(
+  C: T & ComponentConstructor<P, E>,
+  target: HTMLElement,
+  config: AppConfig<P, E> & MountOptions = {}
+): Promise<Component<P, E> & InstanceType<T>> {
+  return new App(C, config).mount(target, config);
+}
@@ -139,7 +139,8 @@ export function updateClass(this: HTMLElement, val: any, oldVal: any) {

 export function makePropSetter(name: string): Setter<HTMLElement> {
  return function setProp(this: HTMLElement, value: any) {
-    (this as any)[name] = value;
+    // support 0, fallback to empty string for other falsy values
+    (this as any)[name] = value === 0 ? 0 : value || "";
  };
 }

@@ -299,12 +299,13 @@ interface BlockCtx {
  locations: IndexedLocation[];
  children: Child[];
  cbRefs: number[];
+  refList: (() => void)[][];
 }

 function buildContext(tree: IntermediateTree, ctx?: BlockCtx, fromIdx?: number): BlockCtx {
  if (!ctx) {
    const children = new Array(tree.info.filter((v) => v.type === "child").length);
-    ctx = { collectors: [], locations: [], children, cbRefs: [], refN: tree.refN };
+    ctx = { collectors: [], locations: [], children, cbRefs: [], refN: tree.refN, refList: [] };
    fromIdx = 0;
  }
  if (tree.refN) {
@@ -408,11 +409,11 @@ function updateCtx(ctx: BlockCtx, tree: IntermediateTree) {
        break;
      }
      case "ref":
-        ctx.cbRefs.push(info.idx);
+        const index = ctx.cbRefs.push(info.idx) - 1;
        ctx.locations.push({
          idx: info.idx,
          refIdx: info.refIdx!,
-          setData: setRef,
+          setData: makeRefSetter(index, ctx.refList),
          updateData: NO_OP,
        });
    }
@@ -426,12 +427,21 @@ function buildBlock(template: HTMLElement, ctx: BlockCtx): BlockType {
  let B = createBlockClass(template, ctx);

  if (ctx.cbRefs.length) {
-    const refs = ctx.cbRefs;
+    const cbRefs = ctx.cbRefs;
+    const refList = ctx.refList;
+    let cbRefsNumber = cbRefs.length;
    B = class extends B {
+      mount(parent: HTMLElement, afterNode: Node | null) {
+        refList.push(new Array(cbRefsNumber));
+        super.mount(parent, afterNode);
+        for (let cbRef of refList.pop()!) {
+          cbRef();
+        }
+      }
      remove() {
        super.remove();
-        for (let ref of refs) {
-          let fn = (this as any).data[ref];
+        for (let cbRef of cbRefs) {
+          let fn = (this as any).data[cbRef];
          fn(null);
        }
      }
@@ -476,12 +486,12 @@ function createBlockClass(template: HTMLElement, ctx: BlockCtx): BlockClass {
  const nodeInsertBefore = nodeProto.insertBefore;
  const elementRemove = elementProto.remove;

-  return class Block {
+  class Block {
    el: HTMLElement | undefined;
-    refs: Node[] | undefined;
-    data: any[] | undefined;
    parentEl?: HTMLElement | undefined;
+    data: any[] | undefined;
    children?: (VNode | undefined)[];
+    refs: Node[] | undefined;

    constructor(data?: any[]) {
      this.data = data;
@@ -502,46 +512,62 @@ function createBlockClass(template: HTMLElement, ctx: BlockCtx): BlockClass {
      nodeInsertBefore.call(this.parentEl, this.el!, target);
    }

+    toString() {
+      const div = document.createElement("div");
+      this.mount(div, null);
+      return div.innerHTML;
+    }
+
    mount(parent: HTMLElement, afterNode: Node | null) {
-      const el = nodeCloneNode.call(template, true);
+      const el = nodeCloneNode.call(template, true) as HTMLElement;
      nodeInsertBefore.call(parent, el, afterNode);
-      if (isDynamic) {
-        // collecting references
-        const refs: Node[] = new Array(refN);
-        this.refs = refs;
-        refs[0] = el;
-        for (let i = 0; i < colN; i++) {
-          const w = collectors[i];
-          refs[w.idx] = w.getVal.call(refs[w.prevIdx]);
-        }
+      this.el = el;
+      this.parentEl = parent;
+    }
+    patch(other: Block, withBeforeRemove: boolean) {}
+  }

-        // applying data to all update points
-        if (locN) {
-          const data = this.data!;
-          for (let i = 0; i < locN; i++) {
-            const loc = locations[i];
-            loc.setData.call(refs[loc.refIdx], data[i]);
-          }
-        }
+  if (isDynamic) {
+    Block.prototype.mount = function mount(parent: HTMLElement, afterNode: Node | null) {
+      const el = nodeCloneNode.call(template, true);
+      // collecting references
+      const refs: Node[] = new Array(refN);
+      this.refs = refs;
+      refs[0] = el;
+      for (let i = 0; i < colN; i++) {
+        const w = collectors[i];
+        refs[w.idx] = w.getVal.call(refs[w.prevIdx]);
+      }

-        // preparing all children
-        if (childN) {
-          const children = this.children;
-          for (let i = 0; i < childN; i++) {
-            const child = children![i];
-            if (child) {
-              const loc = childrenLocs[i];
-              const afterNode = loc.afterRefIdx ? refs[loc.afterRefIdx] : null;
-              child.isOnlyChild = loc.isOnlyChild;
-              child.mount(refs[loc.parentRefIdx] as any, afterNode);
-            }
+      // applying data to all update points
+      if (locN) {
+        const data = this.data!;
+        for (let i = 0; i < locN; i++) {
+          const loc = locations[i];
+          loc.setData.call(refs[loc.refIdx], data[i]);
+        }
+      }
+
+      nodeInsertBefore.call(parent, el, afterNode);
+
+      // preparing all children
+      if (childN) {
+        const children = this.children;
+        for (let i = 0; i < childN; i++) {
+          const child = children![i];
+          if (child) {
+            const loc = childrenLocs[i];
+            const afterNode = loc.afterRefIdx ? refs[loc.afterRefIdx] : null;
+            child.isOnlyChild = loc.isOnlyChild;
+            child.mount(refs[loc.parentRefIdx] as any, afterNode);
          }
        }
      }
      this.el = el as HTMLElement;
      this.parentEl = parent;
-    }
-    patch(other: Block, withBeforeRemove: boolean) {
+    };
+
+    Block.prototype.patch = function patch(other: Block, withBeforeRemove: boolean) {
      if (this === other) {
        return;
      }
@@ -586,19 +612,17 @@ function createBlockClass(template: HTMLElement, ctx: BlockCtx): BlockClass {
          }
        }
      }
-    }
-    toString() {
-      const div = document.createElement("div");
-      this.mount(div, null);
-      return div.innerHTML;
-    }
-  };
+    };
+  }
+  return Block;
 }

 function setText(this: Text, value: any) {
  characterDataSetData.call(this, toText(value));
 }

-function setRef(this: HTMLElement, fn: any) {
-  fn(this);
+function makeRefSetter(index: number, refs: (() => void)[][]): Setter<HTMLElement> {
+  return function setRef(this: HTMLElement, fn: any) {
+    refs[refs.length - 1][index] = () => fn(this);
+  };
 }
@@ -0,0 +1,101 @@
+import { createEventHandler } from "./events";
+import type { VNode } from "./index";
+
+type EventsSpec = { [name: string]: number };
+
+type Catcher = (child: VNode, handlers: any[]) => VNode;
+
+export function createCatcher(eventsSpec: EventsSpec): Catcher {
+  const n = Object.keys(eventsSpec).length;
+
+  class VCatcher {
+    child: VNode;
+    handlerData: any[];
+    handlerFns: any[] = [];
+
+    parentEl?: HTMLElement | undefined;
+    afterNode: Text | null = null;
+
+    constructor(child: VNode, handlers: any[]) {
+      this.child = child;
+      this.handlerData = handlers;
+    }
+
+    mount(parent: HTMLElement, afterNode: Node | null) {
+      this.parentEl = parent;
+      this.child.mount(parent, afterNode);
+      this.afterNode = document.createTextNode("");
+      parent.insertBefore(this.afterNode, afterNode);
+      this.wrapHandlerData();
+      for (let name in eventsSpec) {
+        const index = eventsSpec[name];
+        const handler = createEventHandler(name);
+        this.handlerFns[index] = handler;
+        handler.setup.call(parent, this.handlerData[index]);
+      }
+    }
+
+    wrapHandlerData() {
+      for (let i = 0; i < n; i++) {
+        let handler = this.handlerData[i];
+        // handler = [...mods, fn, comp], so we need to replace second to last elem
+        let idx = handler.length - 2;
+        let origFn = handler[idx];
+        const self = this;
+        handler[idx] = function (ev: any) {
+          const target = ev.target;
+          let currentNode: any = self.child.firstNode();
+          const afterNode = self.afterNode;
+          while (currentNode !== afterNode) {
+            if (currentNode.contains(target)) {
+              return origFn.call(this, ev);
+            }
+            currentNode = currentNode.nextSibling;
+          }
+        };
+      }
+    }
+
+    moveBefore(other: VCatcher | null, afterNode: Node | null) {
+      this.child.moveBefore(other ? other.child : null, afterNode);
+      this.parentEl!.insertBefore(this.afterNode!, afterNode);
+    }
+
+    patch(other: VCatcher, withBeforeRemove: boolean) {
+      if (this === other) {
+        return;
+      }
+      this.handlerData = other.handlerData;
+      this.wrapHandlerData();
+      for (let i = 0; i < n; i++) {
+        this.handlerFns[i].update.call(this.parentEl!, this.handlerData[i]);
+      }
+
+      this.child.patch(other.child, withBeforeRemove);
+    }
+
+    beforeRemove() {
+      this.child.beforeRemove();
+    }
+
+    remove() {
+      for (let i = 0; i < n; i++) {
+        this.handlerFns[i].remove.call(this.parentEl!);
+      }
+      this.child.remove();
+      this.afterNode!.remove();
+    }
+
+    firstNode(): Node | undefined {
+      return this.child.firstNode();
+    }
+
+    toString(): string {
+      return this.child.toString();
+    }
+  }
+
+  return function (child: VNode, handlers: any[]): VNode<VCatcher> {
+    return new VCatcher(child, handlers);
+  };
+}
@@ -5,6 +5,7 @@ type EventHandlerSetter = (this: HTMLElement, data: any) => void;
 interface EventHandlerCreator {
  setup: EventHandlerSetter;
  update: EventHandlerSetter;
+  remove: (this: HTMLElement) => void;
 }

 export function createEventHandler(rawEvent: string): EventHandlerCreator {
@@ -38,11 +39,15 @@ function createElementHandler(evName: string, capture: boolean = false): EventHa
    this.addEventListener(evName, listener, { capture });
  }

+  function remove(this: HTMLElement) {
+    delete (this as any)[eventKey];
+    this.removeEventListener(evName, listener, { capture });
+  }
  function update(this: HTMLElement, data: any) {
    (this as any)[eventKey] = data;
  }

-  return { setup, update };
+  return { setup, update, remove };
 }

 // Synthetic handler: a form of event delegation that allows placing only one
@@ -60,7 +65,12 @@ function createSyntheticHandler(evName: string, capture: boolean = false): Event
    _data[currentId] = data;
    (this as any)[eventKey] = _data;
  }
-  return { setup, update: setup };
+
+  function remove(this: HTMLElement) {
+    delete (this as any)[eventKey];
+  }
+
+  return { setup, update: setup, remove };
 }

 function nativeToSyntheticEvent(eventKey: string, event: Event) {
@@ -61,6 +61,7 @@ class VHtml {
      // remove current content
      this.remove();
      this.content = content;
+      this.html = other.html;
    }
  }

@@ -6,6 +6,7 @@ export { list } from "./list";
 export { multi } from "./multi";
 export { text, comment } from "./text";
 export { html } from "./html";
+export { createCatcher } from "./event_catcher";

 export interface VNode<T = any> {
  mount(parent: HTMLElement, afterNode: Node | null): void;
@@ -9,11 +9,11 @@ const characterDataSetData = getDescriptor(characterDataProto, "data").set!;
 const nodeRemoveChild = nodeProto.removeChild;

 abstract class VSimpleNode {
-  text: string;
+  text: string | String;
  parentEl?: HTMLElement | undefined;
  el?: any;

-  constructor(text: string) {
+  constructor(text: string | String) {
    this.text = text;
  }

@@ -65,7 +65,7 @@ class VComment extends VSimpleNode {
  patch() {}
 }

-export function text(str: string): VNode<VText> {
+export function text(str: string | String): VNode<VText> {
  return new VText(str);
 }

@@ -1,12 +1,30 @@
+import { Schema } from "./validation";
 import type { ComponentNode } from "./component_node";

 // -----------------------------------------------------------------------------
 //  Component Class
 // -----------------------------------------------------------------------------

+type Props = { [key: string]: any };
+
+interface StaticComponentProperties {
+  template: string;
+  defaultProps?: any;
+  props?: Schema;
+  components?: { [componentName: string]: ComponentConstructor };
+}
+
+export type ComponentConstructor<P extends Props = any, E = any> = (new (
+  props: P,
+  env: E,
+  node: ComponentNode
+) => Component<P, E>) &
+  StaticComponentProperties;
+
 export class Component<Props = any, Env = any> {
  static template: string = "";
  static props?: any;
+  static defaultProps?: any;

  props: Props;
  env: Env;
@@ -20,7 +38,7 @@ export class Component<Props = any, Env = any> {

  setup() {}

-  render() {
-    this.__owl__.render();
+  render(deep: boolean = false) {
+    this.__owl__.render(deep === true);
  }
 }
@@ -1,21 +1,26 @@
-import type { App, Env } from "../app/app";
-import { BDom, VNode } from "../blockdom";
-import { Component } from "./component";
+import type { App, Env } from "./app";
+import { BDom, VNode } from "./blockdom";
 import {
-  Fiber,
-  makeChildFiber,
-  makeRootFiber,
-  MountFiber,
-  MountOptions,
-  RootFiber,
-} from "./fibers";
-import { handleError, fibersInError } from "./error_handling";
-import { applyDefaultProps } from "./props_validation";
+  clearReactivesForCallback,
+  getSubscriptions,
+  NonReactive,
+  Reactive,
+  reactive,
+  toRaw,
+  TARGET,
+} from "./reactivity";
+import { batched, Callback } from "./utils";
+import { Component, ComponentConstructor } from "./component";
+import { fibersInError, handleError } from "./error_handling";
+import { Fiber, makeChildFiber, makeRootFiber, MountFiber, MountOptions } from "./fibers";
 import { STATUS } from "./status";

 let currentNode: ComponentNode | null = null;

-export function getCurrent(): ComponentNode | null {
+export function getCurrent(): ComponentNode {
+  if (!currentNode) {
+    throw new Error("No active component (a hook function should only be called in 'setup')");
+  }
  return currentNode;
 }

@@ -23,23 +28,73 @@ export function useComponent(): Component {
  return currentNode!.component;
 }

-export function component(
-  name: string | typeof Component,
-  props: any,
+/**
+ * Apply default props (only top level).
+ */
+function applyDefaultProps<P extends object>(props: P, defaultProps: Partial<P>): P {
+  const result = Object.assign({} as any, props);
+  for (let propName in defaultProps) {
+    if (props[propName] === undefined) {
+      result[propName] = defaultProps[propName];
+    }
+  }
+  return result;
+}
+// -----------------------------------------------------------------------------
+// Integration with reactivity system (useState)
+// -----------------------------------------------------------------------------
+
+const batchedRenderFunctions = new WeakMap<ComponentNode, Callback>();
+/**
+ * Creates a reactive object that will be observed by the current component.
+ * Reading data from the returned object (eg during rendering) will cause the
+ * component to subscribe to that data and be rerendered when it changes.
+ *
+ * @param state the state to observe
+ * @returns a reactive object that will cause the component to re-render on
+ *  relevant changes
+ * @see reactive
+ */
+export function useState<T extends object>(state: T): Reactive<T> | NonReactive<T> {
+  const node = getCurrent();
+  let render = batchedRenderFunctions.get(node)!;
+  if (!render) {
+    render = batched(node.render.bind(node, false));
+    batchedRenderFunctions.set(node, render);
+    // manual implementation of onWillDestroy to break cyclic dependency
+    node.willDestroy.push(clearReactivesForCallback.bind(null, render));
+  }
+  return reactive(state, render);
+}
+
+// -----------------------------------------------------------------------------
+// component function (used in compiled template code)
+// -----------------------------------------------------------------------------
+type Props = { [key: string]: any };
+
+function arePropsDifferent(props1: Props, props2: Props): boolean {
+  for (let k in props1) {
+    const prop1 = props1[k] && typeof props1[k] === "object" ? toRaw(props1[k]) : props1[k];
+    const prop2 = props2[k] && typeof props2[k] === "object" ? toRaw(props2[k]) : props2[k];
+    if (prop1 !== prop2) {
+      return true;
+    }
+  }
+  return Object.keys(props1).length !== Object.keys(props2).length;
+}
+
+export function component<P extends Props>(
+  name: string | ComponentConstructor<P>,
+  props: P,
  key: string,
  ctx: ComponentNode,
  parent: any
-): ComponentNode {
+): ComponentNode<P> {
  let node: any = ctx.children[key];
  let isDynamic = typeof name !== "string";

-  if (node) {
-    if (node.status < STATUS.MOUNTED) {
-      node.destroy();
-      node = undefined;
-    } else if (node.status === STATUS.DESTROYED) {
-      node = undefined;
-    }
+  if (node && node.status === STATUS.DESTROYED) {
+    node = undefined;
  }
  if (isDynamic && node && node.component.constructor !== name) {
    node = undefined;
@@ -47,7 +102,16 @@ export function component(

  const parentFiber = ctx.fiber!;
  if (node) {
-    node.updateAndRender(props, parentFiber);
+    let shouldRender = node.forceNextRender;
+    if (shouldRender) {
+      node.forceNextRender = false;
+    } else {
+      const currentProps = node.props;
+      shouldRender = parentFiber.deep || arePropsDifferent(currentProps, props);
+    }
+    if (shouldRender) {
+      node.updateAndRender(props, parentFiber);
+    }
  } else {
    // new component
    let C;
@@ -57,32 +121,34 @@ export function component(
      C = parent.constructor.components[name as any];
      if (!C) {
        throw new Error(`Cannot find the definition of component "${name}"`);
+      } else if (!(C.prototype instanceof Component)) {
+        throw new Error(`"${name}" is not a Component. It must inherit from the Component class`);
      }
    }
-    node = new ComponentNode(C, props, ctx.app, ctx);
+    node = new ComponentNode(C, props, ctx.app, ctx, key);
    ctx.children[key] = node;
-
-    const fiber = makeChildFiber(node, parentFiber);
-    node.initiateRender(fiber);
+    node.initiateRender(new Fiber(node, parentFiber));
  }
+  parentFiber.childrenMap[key] = node;
  return node;
 }

 // -----------------------------------------------------------------------------
-//  Component VNode
+//  Component VNode class
 // -----------------------------------------------------------------------------

 type LifecycleHook = Function;

-export class ComponentNode<T extends typeof Component = typeof Component>
-  implements VNode<ComponentNode>
-{
+export class ComponentNode<P extends Props = any, E = any> implements VNode<ComponentNode<P, E>> {
  el?: HTMLElement | Text | undefined;
  app: App;
  fiber: Fiber | null = null;
-  component: InstanceType<T>;
+  component: Component<P, E>;
  bdom: BDom | null = null;
  status: STATUS = STATUS.NEW;
+  forceNextRender: boolean = false;
+  parentKey: string | null;
+  props: P;

  renderFn: Function;
  parent: ComponentNode | null;
@@ -99,17 +165,35 @@ export class ComponentNode<T extends typeof Component = typeof Component>
  patched: LifecycleHook[] = [];
  willDestroy: LifecycleHook[] = [];

-  constructor(C: T, props: any, app: App, parent?: ComponentNode) {
+  constructor(
+    C: ComponentConstructor<P, E>,
+    props: P,
+    app: App,
+    parent: ComponentNode | null,
+    parentKey: string | null
+  ) {
    currentNode = this;
    this.app = app;
-    this.parent = parent || null;
+    this.parent = parent;
+    this.props = props;
+    this.parentKey = parentKey;
    this.level = parent ? parent.level + 1 : 0;
-    applyDefaultProps(props, C);
+    const defaultProps = C.defaultProps;
+    if (defaultProps) {
+      props = applyDefaultProps(props, defaultProps);
+    }
    const env = (parent && parent.childEnv) || app.env;
    this.childEnv = env;
-    this.component = new C(props, env, this) as any;
+    for (const key in props) {
+      const prop = props[key];
+      if (prop && typeof prop === "object" && prop[TARGET]) {
+        props[key] = useState(prop);
+      }
+    }
+    this.component = new C(props, env, this);
    this.renderFn = app.getTemplate(C.template).bind(this.component, this.component, this);
    this.component.setup();
+    currentNode = null;
  }

  mountComponent(target: any, options?: MountOptions) {
@@ -131,26 +215,35 @@ export class ComponentNode<T extends typeof Component = typeof Component>
      return;
    }
    if (this.status === STATUS.NEW && this.fiber === fiber) {
-      this._render(fiber);
+      fiber.render();
    }
  }

-  async render() {
+  async render(deep: boolean) {
    let current = this.fiber;
-    if (current && current.root!.locked) {
+    if (current && (current.root!.locked || (current as any).bdom === true)) {
      await Promise.resolve();
      // situation may have changed after the microtask tick
      current = this.fiber;
    }
-    if (current && !current.bdom && !fibersInError.has(current)) {
-      return;
-    }
-    if (!this.bdom && !current) {
+    if (current) {
+      if (!current.bdom && !fibersInError.has(current)) {
+        if (deep) {
+          // we want the render from this point on to be with deep=true
+          current.deep = deep;
+        }
+        return;
+      }
+      // if current rendering was with deep=true, we want this one to be the same
+      deep = deep || current.deep;
+    } else if (!this.bdom) {
      return;
    }

    const fiber = makeRootFiber(this);
+    fiber.deep = deep;
    this.fiber = fiber;
+
    this.app.scheduler.addFiber(fiber);
    await Promise.resolve();
    if (this.status === STATUS.DESTROYED) {
@@ -168,16 +261,7 @@ export class ComponentNode<T extends typeof Component = typeof Component>
    //   embedded in a rendering coming from above, so the fiber will be rendered
    //   in the next microtick anyway, so we should not render it again.
    if (this.fiber === fiber && (current || !fiber.parent)) {
-      this._render(fiber);
-    }
-  }
-
-  _render(fiber: Fiber | RootFiber) {
-    try {
-      fiber.bdom = this.renderFn();
-      fiber.root!.counter--;
-    } catch (e) {
-      handleError({ node: this, error: e });
+      fiber.render();
    }
  }

@@ -199,25 +283,45 @@ export class ComponentNode<T extends typeof Component = typeof Component>
    for (let child of Object.values(this.children)) {
      child._destroy();
    }
-    for (let cb of this.willDestroy) {
-      cb.call(component);
+    if (this.willDestroy.length) {
+      try {
+        for (let cb of this.willDestroy) {
+          cb.call(component);
+        }
+      } catch (e) {
+        handleError({ error: e, node: this });
+      }
    }
    this.status = STATUS.DESTROYED;
  }

-  async updateAndRender(props: any, parentFiber: Fiber) {
+  async updateAndRender(props: P, parentFiber: Fiber) {
+    const rawProps = props;
    // update
    const fiber = makeChildFiber(this, parentFiber);
    this.fiber = fiber;
    const component = this.component;
-    applyDefaultProps(props, component.constructor as any);
+    const defaultProps = (component.constructor as any).defaultProps;
+    if (defaultProps) {
+      props = applyDefaultProps(props, defaultProps);
+    }
+
+    currentNode = this;
+    for (const key in props) {
+      const prop = props[key];
+      if (prop && typeof prop === "object" && prop[TARGET]) {
+        props[key] = useState(prop);
+      }
+    }
+    currentNode = null;
    const prom = Promise.all(this.willUpdateProps.map((f) => f.call(component, props)));
    await prom;
    if (fiber !== this.fiber) {
      return;
    }
    component.props = props;
-    this._render(fiber);
+    this.props = rawProps;
+    fiber.render();
    const parentRoot = parentFiber.root!;
    if (this.willPatch.length) {
      parentRoot.willPatch.push(fiber);
@@ -267,6 +371,7 @@ export class ComponentNode<T extends typeof Component = typeof Component>
    bdom.mount(parent, anchor);
    this.status = STATUS.MOUNTED;
    this.fiber!.appliedToDom = true;
+    this.children = this.fiber!.childrenMap;
    this.fiber = null;
  }

@@ -275,11 +380,17 @@ export class ComponentNode<T extends typeof Component = typeof Component>
  }

  patch() {
-    const hasChildren = Object.keys(this.children).length > 0;
-    this.bdom!.patch(this!.fiber!.bdom!, hasChildren);
-    if (hasChildren) {
-      this.cleanOutdatedChildren();
+    if (this.fiber && this.fiber.parent) {
+      // we only patch here renderings coming from above. renderings initiated
+      // by the component will be patched independently in the appropriate
+      // fiber.complete
+      this._patch();
    }
+  }
+  _patch() {
+    const hasChildren = Object.keys(this.children).length > 0;
+    this.children = this.fiber!.childrenMap;
+    this.bdom!.patch(this!.fiber!.bdom!, hasChildren);
    this.fiber!.appliedToDom = true;
    this.fiber = null;
  }
@@ -292,17 +403,15 @@ export class ComponentNode<T extends typeof Component = typeof Component>
    this.bdom!.remove();
  }

-  cleanOutdatedChildren() {
-    const children = this.children;
-    for (const key in children) {
-      const node = children[key];
-      const status = node.status;
-      if (status !== STATUS.MOUNTED) {
-        delete children[key];
-        if (status !== STATUS.DESTROYED) {
-          node.destroy();
-        }
-      }
-    }
+  // ---------------------------------------------------------------------------
+  // Some debug helpers
+  // ---------------------------------------------------------------------------
+  get name(): string {
+    return this.component.constructor.name;
+  }
+
+  get subscriptions(): ReturnType<typeof getSubscriptions> {
+    const render = batchedRenderFunctions.get(this);
+    return render ? getSubscriptions(render) : [];
  }
 }
@@ -5,7 +5,7 @@ import type { Fiber } from "./fibers";
 export const fibersInError: WeakMap<Fiber, any> = new WeakMap();
 export const nodeErrorHandlers: WeakMap<ComponentNode, ((error: any) => void)[]> = new WeakMap();

-function _handleError(node: ComponentNode | null, error: any, isFirstRound = false): boolean {
+function _handleError(node: ComponentNode | null, error: any): boolean {
  if (!node) {
    return false;
  }
@@ -16,22 +16,19 @@ function _handleError(node: ComponentNode | null, error: any, isFirstRound = fal

  const errorHandlers = nodeErrorHandlers.get(node);
  if (errorHandlers) {
-    let stopped = false;
+    let handled = false;
    // execute in the opposite order
    for (let i = errorHandlers.length - 1; i >= 0; i--) {
      try {
        errorHandlers[i](error);
-        stopped = true;
+        handled = true;
        break;
      } catch (e) {
        error = e;
      }
    }

-    if (stopped) {
-      if (isFirstRound && fiber && fiber.node.fiber) {
-        fiber.root!.counter--;
-      }
+    if (handled) {
      return true;
    }
  }
@@ -54,7 +51,7 @@ export function handleError(params: ErrorParams) {

  fibersInError.set(fiber.root!, error);

-  const handled = _handleError(node, error, true);
+  const handled = _handleError(node, error);
  if (!handled) {
    console.warn(`[Owl] Unhandled error. Destroying the root component`);
    try {
@@ -1,4 +1,4 @@
-import { filterOutModifiersFromData } from "../blockdom/config";
+import { filterOutModifiersFromData } from "./blockdom/config";
 import { STATUS } from "./status";

 export const mainEventHandler = (data: any, ev: Event, currentTarget?: EventTarget | null) => {
@@ -1,4 +1,4 @@
-import { BDom, mount } from "../blockdom";
+import { BDom, mount } from "./blockdom";
 import type { ComponentNode } from "./component_node";
 import { fibersInError, handleError } from "./error_handling";
 import { STATUS } from "./status";
@@ -6,8 +6,7 @@ import { STATUS } from "./status";
 export function makeChildFiber(node: ComponentNode, parent: Fiber): Fiber {
  let current = node.fiber;
  if (current) {
-    let root = parent.root;
-    cancelFibers(root, current.children);
+    cancelFibers(current.children);
    current.root = null;
  }
  return new Fiber(node, parent);
@@ -17,9 +16,14 @@ export function makeRootFiber(node: ComponentNode): Fiber {
  let current = node.fiber;
  if (current) {
    let root = current.root!;
-    root.counter -= cancelFibers(root, current.children);
+    // lock root fiber because canceling children fibers may destroy components,
+    // which means any arbitrary code can be run in onWillDestroy, which may
+    // trigger new renderings
+    root.locked = true;
+    root.setCounter(root.counter + 1 - cancelFibers(current.children));
+    root.locked = false;
    current.children = [];
-    root.counter++;
+    current.childrenMap = {};
    current.bdom = null;
    if (fibersInError.has(current)) {
      fibersInError.delete(current);
@@ -35,22 +39,37 @@ export function makeRootFiber(node: ComponentNode): Fiber {
  if (node.patched.length) {
    fiber.patched.push(fiber);
  }
-
  return fiber;
 }

+function throwOnRender() {
+  throw new Error("Attempted to render cancelled fiber");
+}
+
 /**
 * @returns number of not-yet rendered fibers cancelled
 */
-function cancelFibers(root: any, fibers: Fiber[]): number {
+function cancelFibers(fibers: Fiber[]): number {
  let result = 0;
  for (let fiber of fibers) {
-    fiber.node.fiber = null;
-    fiber.root = root;
-    if (!fiber.bdom) {
+    let node = fiber.node;
+    fiber.render = throwOnRender;
+    if (node.status === STATUS.NEW) {
+      node.destroy();
+    }
+    node.fiber = null;
+    if (fiber.bdom) {
+      // if fiber has been rendered, this means that the component props have
+      // been updated. however, this fiber will not be patched to the dom, so
+      // it could happen that the next render compare the current props with
+      // the same props, and skip the render completely. With the next line,
+      // we kindly request the component code to force a render, so it works as
+      // expected.
+      node.forceNextRender = true;
+    } else {
      result++;
    }
-    result += cancelFibers(root, fiber.children);
+    result += cancelFibers(fiber.children);
  }
  return result;
 }
@@ -62,19 +81,59 @@ export class Fiber {
  parent: Fiber | null;
  children: Fiber[] = [];
  appliedToDom = false;
+  deep: boolean = false;
+  childrenMap: ComponentNode["children"] = {};

  constructor(node: ComponentNode, parent: Fiber | null) {
    this.node = node;
    this.parent = parent;
    if (parent) {
+      this.deep = parent.deep;
      const root = parent.root!;
-      root.counter++;
+      root.setCounter(root.counter + 1);
      this.root = root;
      parent.children.push(this);
    } else {
      this.root = this as any;
    }
  }
+
+  render() {
+    // if some parent has a fiber => register in followup
+    let prev = this.root!.node;
+    let scheduler = prev.app.scheduler;
+    let current = prev.parent;
+    while (current) {
+      if (current.fiber) {
+        let root = current.fiber.root!;
+        if (root.counter === 0 && prev.parentKey! in current.fiber.childrenMap) {
+          current = root.node;
+        } else {
+          scheduler.delayedRenders.push(this);
+          return;
+        }
+      }
+      prev = current;
+      current = current.parent;
+    }
+
+    // there are no current rendering from above => we can render
+    this._render();
+  }
+
+  _render() {
+    const node = this.node;
+    const root = this.root;
+    if (root) {
+      try {
+        (this.bdom as any) = true;
+        this.bdom = node.renderFn();
+      } catch (e) {
+        handleError({ node, error: e });
+      }
+      root.setCounter(root.counter - 1);
+    }
+  }
 }

 export class RootFiber extends Fiber {
@@ -109,7 +168,7 @@ export class RootFiber extends Fiber {
      current = undefined;

      // Step 2: patching the dom
-      node.patch();
+      node._patch();
      this.locked = false;

      // Step 4: calling all mounted lifecycle hooks
@@ -138,6 +197,13 @@ export class RootFiber extends Fiber {
      handleError({ fiber: current || this, error: e });
    }
  }
+
+  setCounter(newValue: number) {
+    this.counter = newValue;
+    if (newValue === 0) {
+      this.node.app.scheduler.flush();
+    }
+  }
 }

 type Position = "first-child" | "last-child";
@@ -159,6 +225,8 @@ export class MountFiber extends RootFiber {
    let current: Fiber | undefined = this;
    try {
      const node = this.node;
+      node.children = this.childrenMap;
+      (node.app.constructor as any).validateTarget(this.target);
      if (node.bdom) {
        // this is a complicated situation: if we mount a fiber with an existing
        // bdom, this means that this same fiber was already completed, mounted,
@@ -1,6 +1,6 @@
-import type { Env } from "./app/app";
-import { getCurrent } from "./component/component_node";
-import { onMounted, onPatched, onWillUnmount } from "./component/lifecycle_hooks";
+import type { Env } from "./app";
+import { getCurrent } from "./component_node";
+import { onMounted, onPatched, onWillUnmount } from "./lifecycle_hooks";

 // -----------------------------------------------------------------------------
 // useRef
@@ -11,7 +11,7 @@ import { onMounted, onPatched, onWillUnmount } from "./component/lifecycle_hooks
 * html node or component.
 */
 export function useRef<T extends HTMLElement = HTMLElement>(name: string): { el: T | null } {
-  const node = getCurrent()!;
+  const node = getCurrent();
  const refs = node.refs;
  return {
    get el(): T | null {
@@ -29,7 +29,13 @@ export function useRef<T extends HTMLElement = HTMLElement>(name: string): { el:
 * need a reference to the env of the component calling them.
 */
 export function useEnv<E extends Env>(): E {
-  return getCurrent()!.component.env as any;
+  return getCurrent().component.env as any;
+}
+
+function extendEnv(currentEnv: Object, extension: Object): Object {
+  const env = Object.create(currentEnv);
+  const descrs = Object.getOwnPropertyDescriptors(extension);
+  return Object.freeze(Object.defineProperties(env, descrs));
 }

 /**
@@ -38,17 +44,19 @@ export function useEnv<E extends Env>(): E {
 * constructor method.
 */
 export function useSubEnv(envExtension: Env) {
-  const node = getCurrent()!;
-  const env = Object.create(node.childEnv);
-  const descrs = Object.getOwnPropertyDescriptors(envExtension);
-  node.childEnv = Object.freeze(Object.defineProperties(env, descrs));
+  const node = getCurrent();
+  node.component.env = extendEnv(node.component.env as any, envExtension);
+  useChildSubEnv(envExtension);
 }

+export function useChildSubEnv(envExtension: Env) {
+  const node = getCurrent();
+  node.childEnv = extendEnv(node.childEnv, envExtension);
+}
 // -----------------------------------------------------------------------------
 // useEffect
 // -----------------------------------------------------------------------------

-const NO_OP = () => {};
 /**
 * @param {...any} dependencies the dependencies computed by computeDependencies
 * @returns {void|(()=>void)} a cleanup function that reverses the side
@@ -69,11 +77,11 @@ type Effect = (...dependencies: any[]) => void | (() => void);
 *      NaN !== NaN, which will cause the effect to rerun on every patch.
 */
 export function useEffect(effect: Effect, computeDependencies: () => any[] = () => [NaN]) {
-  let cleanup: () => void;
+  let cleanup: (() => void) | void;
  let dependencies: any[];
  onMounted(() => {
    dependencies = computeDependencies();
-    cleanup = effect(...dependencies) || NO_OP;
+    cleanup = effect(...dependencies);
  });

  onPatched(() => {
@@ -81,12 +89,14 @@ export function useEffect(effect: Effect, computeDependencies: () => any[] = ()
    const shouldReapply = newDeps.some((val, i) => val !== dependencies[i]);
    if (shouldReapply) {
      dependencies = newDeps;
-      cleanup();
-      cleanup = effect(...dependencies) || NO_OP;
+      if (cleanup) {
+        cleanup();
+      }
+      cleanup = effect(...dependencies);
    }
  });

-  onWillUnmount(() => cleanup());
+  onWillUnmount(() => cleanup && cleanup());
 }

 // -----------------------------------------------------------------------------
@@ -112,7 +122,7 @@ export function useExternalListener(
  handler: EventListener,
  eventParams?: AddEventListenerOptions
 ) {
-  const node = getCurrent()!;
+  const node = getCurrent();
  const boundHandler = handler.bind(node.component);
  onMounted(() => target.addEventListener(eventName, boundHandler, eventParams));
  onWillUnmount(() => target.removeEventListener(eventName, boundHandler, eventParams));
@@ -0,0 +1,58 @@
+import {
+  config,
+  createBlock,
+  html,
+  list,
+  mount as blockMount,
+  multi,
+  patch,
+  remove,
+  text,
+  toggler,
+  comment,
+} from "./blockdom";
+import { mainEventHandler } from "./event_handling";
+export type { Reactive } from "./reactivity";
+
+config.shouldNormalizeDom = false;
+config.mainEventHandler = mainEventHandler;
+
+export const blockDom = {
+  config,
+  // bdom entry points
+  mount: blockMount,
+  patch,
+  remove,
+  // bdom block types
+  list,
+  multi,
+  text,
+  toggler,
+  createBlock,
+  html,
+  comment,
+};
+
+export { App, mount } from "./app";
+export { xml } from "./template_set";
+export { Component } from "./component";
+export { useComponent, useState } from "./component_node";
+export { status } from "./status";
+export { reactive, markRaw, toRaw } from "./reactivity";
+export { useEffect, useEnv, useExternalListener, useRef, useChildSubEnv, useSubEnv } from "./hooks";
+export { EventBus, whenReady, loadFile, markup } from "./utils";
+export {
+  onWillStart,
+  onMounted,
+  onWillUnmount,
+  onWillUpdateProps,
+  onWillPatch,
+  onPatched,
+  onWillRender,
+  onRendered,
+  onWillDestroy,
+  onError,
+} from "./lifecycle_hooks";
+export { validate } from "./validation";
+
+export const __info__ = {};
@@ -0,0 +1,122 @@
+import { getCurrent } from "./component_node";
+import { nodeErrorHandlers } from "./error_handling";
+
+const TIMEOUT = Symbol("timeout");
+function wrapError(fn: (...args: any[]) => any, hookName: string) {
+  const error = new Error(`The following error occurred in ${hookName}: `) as Error & {
+    cause: any;
+  };
+  const timeoutError = new Error(`${hookName}'s promise hasn't resolved after 3 seconds`);
+  const node = getCurrent();
+  return (...args: any[]) => {
+    try {
+      const result = fn(...args);
+      if (result instanceof Promise) {
+        if (hookName === "onWillStart" || hookName === "onWillUpdateProps") {
+          const fiber = node.fiber;
+          Promise.race([
+            result,
+            new Promise((resolve) => setTimeout(() => resolve(TIMEOUT), 3000)),
+          ]).then((res) => {
+            if (res === TIMEOUT && node.fiber === fiber) {
+              console.warn(timeoutError);
+            }
+          });
+        }
+        return result.catch((cause) => {
+          error.cause = cause;
+          if (cause instanceof Error) {
+            error.message += `"${cause.message}"`;
+          }
+          throw error;
+        });
+      }
+      return result;
+    } catch (cause) {
+      if (cause instanceof Error) {
+        error.message += `"${cause.message}"`;
+      }
+      throw error;
+    }
+  };
+}
+
+// -----------------------------------------------------------------------------
+//  hooks
+// -----------------------------------------------------------------------------
+
+export function onWillStart(fn: () => Promise<void> | void | any) {
+  const node = getCurrent();
+  const decorate = node.app.dev ? wrapError : (fn: any) => fn;
+  node.willStart.push(decorate(fn.bind(node.component), "onWillStart"));
+}
+
+export function onWillUpdateProps(fn: (nextProps: any) => Promise<void> | void | any) {
+  const node = getCurrent();
+  const decorate = node.app.dev ? wrapError : (fn: any) => fn;
+  node.willUpdateProps.push(decorate(fn.bind(node.component), "onWillUpdateProps"));
+}
+
+export function onMounted(fn: () => void | any) {
+  const node = getCurrent();
+  const decorate = node.app.dev ? wrapError : (fn: any) => fn;
+  node.mounted.push(decorate(fn.bind(node.component), "onMounted"));
+}
+
+export function onWillPatch(fn: () => Promise<void> | any | void) {
+  const node = getCurrent();
+  const decorate = node.app.dev ? wrapError : (fn: any) => fn;
+  node.willPatch.unshift(decorate(fn.bind(node.component), "onWillPatch"));
+}
+
+export function onPatched(fn: () => void | any) {
+  const node = getCurrent();
+  const decorate = node.app.dev ? wrapError : (fn: any) => fn;
+  node.patched.push(decorate(fn.bind(node.component), "onPatched"));
+}
+
+export function onWillUnmount(fn: () => Promise<void> | void | any) {
+  const node = getCurrent();
+  const decorate = node.app.dev ? wrapError : (fn: any) => fn;
+  node.willUnmount.unshift(decorate(fn.bind(node.component), "onWillUnmount"));
+}
+
+export function onWillDestroy(fn: () => Promise<void> | void | any) {
+  const node = getCurrent();
+  const decorate = node.app.dev ? wrapError : (fn: any) => fn;
+  node.willDestroy.push(decorate(fn.bind(node.component), "onWillDestroy"));
+}
+
+export function onWillRender(fn: () => void | any) {
+  const node = getCurrent();
+  const renderFn = node.renderFn;
+  const decorate = node.app.dev ? wrapError : (fn: any) => fn;
+  fn = decorate(fn.bind(node.component), "onWillRender");
+  node.renderFn = () => {
+    fn();
+    return renderFn();
+  };
+}
+
+export function onRendered(fn: () => void | any) {
+  const node = getCurrent();
+  const renderFn = node.renderFn;
+  const decorate = node.app.dev ? wrapError : (fn: any) => fn;
+  fn = decorate(fn.bind(node.component), "onRendered");
+  node.renderFn = () => {
+    const result = renderFn();
+    fn();
+    return result;
+  };
+}
+
+type OnErrorCallback = (error: any) => void | any;
+export function onError(callback: OnErrorCallback) {
+  const node = getCurrent();
+  let handlers = nodeErrorHandlers.get(node);
+  if (!handlers) {
+    handlers = [];
+    nodeErrorHandlers.set(node, handlers);
+  }
+  handlers.push(callback.bind(node.component));
+}
@@ -1,7 +1,6 @@
-import { onWillUnmount } from "./component/lifecycle_hooks";
-import { xml } from "./app/template_set";
+import { onWillUnmount } from "./lifecycle_hooks";
 import { BDom, text, VNode } from "./blockdom";
-import { Component } from "./component/component";
+import { Component } from "./component";

 const VText: any = text("").constructor;

@@ -53,8 +52,18 @@ class VPortal extends VText implements Partial<VNode<VPortal>> {
  }
 }

+/**
+ * <t t-slot="default"/>
+ */
+export function portalTemplate(app: any, bdom: any, helpers: any) {
+  let { callSlot } = helpers;
+  return function template(ctx: any, node: any, key = "") {
+    return callSlot(ctx, node, key, "default", false, null);
+  };
+}
+
 export class Portal extends Component {
-  static template = xml`<t t-slot="default"/>`;
+  static template = "__portal__";
  static props = {
    target: {
      type: String,
@@ -0,0 +1,457 @@
+import { Callback } from "./utils";
+
+// Allows to get the target of a Reactive (used for making a new Reactive from the underlying object)
+export const TARGET = Symbol("Target");
+// Escape hatch to prevent reactivity system to turn something into a reactive
+const SKIP = Symbol("Skip");
+// Special key to subscribe to, to be notified of key creation/deletion
+const KEYCHANGES = Symbol("Key changes");
+
+type Target = object;
+type Collection = Set<any> | Map<any, any> | WeakMap<any, any>;
+type CollectionRawType = "Set" | "Map" | "WeakMap";
+
+export type Reactive<T extends Target = Target> = T & {
+  [TARGET]: any;
+};
+
+export type NonReactive<T extends Target = Target> = T & {
+  [SKIP]: any;
+};
+
+const objectToString = Object.prototype.toString;
+const objectHasOwnProperty = Object.prototype.hasOwnProperty;
+
+const SUPPORTED_RAW_TYPES = new Set(["Object", "Array", "Set", "Map", "WeakMap"]);
+const COLLECTION_RAWTYPES = new Set(["Set", "Map", "WeakMap"]);
+
+/**
+ * extract "RawType" from strings like "[object RawType]" => this lets us ignore
+ * many native objects such as Promise (whose toString is [object Promise])
+ * or Date ([object Date]), while also supporting collections without using
+ * instanceof in a loop
+ *
+ * @param obj the object to check
+ * @returns the raw type of the object
+ */
+function rawType(obj: any) {
+  return objectToString.call(obj).slice(8, -1);
+}
+/**
+ * Checks whether a given value can be made into a reactive object.
+ *
+ * @param value the value to check
+ * @returns whether the value can be made reactive
+ */
+function canBeMadeReactive(value: any): boolean {
+  if (typeof value !== "object") {
+    return false;
+  }
+  return SUPPORTED_RAW_TYPES.has(rawType(value));
+}
+/**
+ * Creates a reactive from the given object/callback if possible and returns it,
+ * returns the original object otherwise.
+ *
+ * @param value the value make reactive
+ * @returns a reactive for the given object when possible, the original otherwise
+ */
+function possiblyReactive(val: any, cb: Callback) {
+  return canBeMadeReactive(val) ? reactive(val, cb) : val;
+}
+
+/**
+ * Mark an object or array so that it is ignored by the reactivity system
+ *
+ * @param value the value to mark
+ * @returns the object itself
+ */
+export function markRaw<T extends Target>(value: T): NonReactive<T> {
+  (value as any)[SKIP] = true;
+  return value as NonReactive<T>;
+}
+
+/**
+ * Given a reactive objet, return the raw (non reactive) underlying object
+ *
+ * @param value a reactive value
+ * @returns the underlying value
+ */
+export function toRaw<T extends object>(value: Reactive<T>): T {
+  return value[TARGET] || value;
+}
+
+const targetToKeysToCallbacks = new WeakMap<Target, Map<PropertyKey, Set<Callback>>>();
+/**
+ * Observes a given key on a target with an callback. The callback will be
+ * called when the given key changes on the target.
+ *
+ * @param target the target whose key should be observed
+ * @param key the key to observe (or Symbol(KEYCHANGES) for key creation
+ *  or deletion)
+ * @param callback the function to call when the key changes
+ */
+function observeTargetKey(target: Target, key: PropertyKey, callback: Callback): void {
+  if (!targetToKeysToCallbacks.get(target)) {
+    targetToKeysToCallbacks.set(target, new Map());
+  }
+  const keyToCallbacks = targetToKeysToCallbacks.get(target)!;
+  if (!keyToCallbacks.get(key)) {
+    keyToCallbacks.set(key, new Set());
+  }
+  keyToCallbacks.get(key)!.add(callback);
+  if (!callbacksToTargets.has(callback)) {
+    callbacksToTargets.set(callback, new Set());
+  }
+  callbacksToTargets.get(callback)!.add(target);
+}
+/**
+ * Notify Reactives that are observing a given target that a key has changed on
+ * the target.
+ *
+ * @param target target whose Reactives should be notified that the target was
+ *  changed.
+ * @param key the key that changed (or Symbol `KEYCHANGES` if a key was created
+ *   or deleted)
+ */
+function notifyReactives(target: Target, key: PropertyKey): void {
+  const keyToCallbacks = targetToKeysToCallbacks.get(target);
+  if (!keyToCallbacks) {
+    return;
+  }
+  const callbacks = keyToCallbacks.get(key);
+  if (!callbacks) {
+    return;
+  }
+  // Loop on copy because clearReactivesForCallback will modify the set in place
+  for (const callback of [...callbacks]) {
+    clearReactivesForCallback(callback);
+    callback();
+  }
+}
+
+const callbacksToTargets = new WeakMap<Callback, Set<Target>>();
+/**
+ * Clears all subscriptions of the Reactives associated with a given callback.
+ *
+ * @param callback the callback for which the reactives need to be cleared
+ */
+export function clearReactivesForCallback(callback: Callback): void {
+  const targetsToClear = callbacksToTargets.get(callback);
+  if (!targetsToClear) {
+    return;
+  }
+  for (const target of targetsToClear) {
+    const observedKeys = targetToKeysToCallbacks.get(target);
+    if (!observedKeys) {
+      continue;
+    }
+    for (const callbacks of observedKeys.values()) {
+      callbacks.delete(callback);
+    }
+  }
+  targetsToClear.clear();
+}
+
+export function getSubscriptions(callback: Callback) {
+  const targets = callbacksToTargets.get(callback) || [];
+  return [...targets].map((target) => {
+    const keysToCallbacks = targetToKeysToCallbacks.get(target);
+    return {
+      target,
+      keys: keysToCallbacks ? [...keysToCallbacks.keys()] : [],
+    };
+  });
+}
+
+const reactiveCache = new WeakMap<Target, WeakMap<Callback, Reactive>>();
+/**
+ * Creates a reactive proxy for an object. Reading data on the reactive object
+ * subscribes to changes to the data. Writing data on the object will cause the
+ * notify callback to be called if there are suscriptions to that data. Nested
+ * objects and arrays are automatically made reactive as well.
+ *
+ * Whenever you are notified of a change, all subscriptions are cleared, and if
+ * you would like to be notified of any further changes, you should go read
+ * the underlying data again. We assume that if you don't go read it again after
+ * being notified, it means that you are no longer interested in that data.
+ *
+ * Subscriptions:
+ * + Reading a property on an object will subscribe you to changes in the value
+ *    of that property.
+ * + Accessing an object keys (eg with Object.keys or with `for..in`) will
+ *    subscribe you to the creation/deletion of keys. Checking the presence of a
+ *    key on the object with 'in' has the same effect.
+ * - getOwnPropertyDescriptor does not currently subscribe you to the property.
+ *    This is a choice that was made because changing a key's value will trigger
+ *    this trap and we do not want to subscribe by writes. This also means that
+ *    Object.hasOwnProperty doesn't subscribe as it goes through this trap.
+ *
+ * @param target the object for which to create a reactive proxy
+ * @param callback the function to call when an observed property of the
+ *  reactive has changed
+ * @returns a proxy that tracks changes to it
+ */
+export function reactive<T extends Target>(
+  target: T,
+  callback: Callback = () => {}
+): Reactive<T> | NonReactive<T> {
+  if (!canBeMadeReactive(target)) {
+    throw new Error(`Cannot make the given value reactive`);
+  }
+  if (SKIP in target) {
+    return target as NonReactive<T>;
+  }
+  const originalTarget = (target as Reactive)[TARGET];
+  if (originalTarget) {
+    return reactive(originalTarget, callback);
+  }
+  if (!reactiveCache.has(target)) {
+    reactiveCache.set(target, new WeakMap());
+  }
+  const reactivesForTarget = reactiveCache.get(target)!;
+  if (!reactivesForTarget.has(callback)) {
+    const targetRawType = rawType(target);
+    const handler = COLLECTION_RAWTYPES.has(targetRawType)
+      ? collectionsProxyHandler(target as Collection, callback, targetRawType as CollectionRawType)
+      : basicProxyHandler<T>(callback);
+    const proxy = new Proxy(target, handler as ProxyHandler<T>) as Reactive<T>;
+    reactivesForTarget.set(callback, proxy);
+  }
+  return reactivesForTarget.get(callback) as Reactive<T>;
+}
+/**
+ * Creates a basic proxy handler for regular objects and arrays.
+ *
+ * @param callback @see reactive
+ * @returns a proxy handler object
+ */
+function basicProxyHandler<T extends Target>(callback: Callback): ProxyHandler<T> {
+  return {
+    get(target: any, key: PropertyKey, proxy: Reactive<T>) {
+      if (key === TARGET) {
+        return target;
+      }
+      // non-writable non-configurable properties cannot be made reactive
+      const desc = Object.getOwnPropertyDescriptor(target, key);
+      if (desc && !desc.writable && !desc.configurable) {
+        return Reflect.get(target, key, proxy);
+      }
+      observeTargetKey(target, key, callback);
+      return possiblyReactive(Reflect.get(target, key, proxy), callback);
+    },
+    set(target, key, value, proxy) {
+      const isNewKey = !objectHasOwnProperty.call(target, key);
+      const originalValue = Reflect.get(target, key, proxy);
+      const ret = Reflect.set(target, key, value, proxy);
+      if (isNewKey) {
+        notifyReactives(target, KEYCHANGES);
+      }
+      // While Array length may trigger the set trap, it's not actually set by this
+      // method but is updated behind the scenes, and the trap is not called with the
+      // new value. We disable the "same-value-optimization" for it because of that.
+      if (originalValue !== value || (Array.isArray(target) && key === "length")) {
+        notifyReactives(target, key);
+      }
+      return ret;
+    },
+    deleteProperty(target, key) {
+      const ret = Reflect.deleteProperty(target, key);
+      // TODO: only notify when something was actually deleted
+      notifyReactives(target, KEYCHANGES);
+      notifyReactives(target, key);
+      return ret;
+    },
+    ownKeys(target) {
+      observeTargetKey(target, KEYCHANGES, callback);
+      return Reflect.ownKeys(target);
+    },
+    has(target, key) {
+      // TODO: this observes all key changes instead of only the presence of the argument key
+      // observing the key itself would observe value changes instead of presence changes
+      // so we may need a finer grained system to distinguish observing value vs presence.
+      observeTargetKey(target, KEYCHANGES, callback);
+      return Reflect.has(target, key);
+    },
+  } as ProxyHandler<T>;
+}
+/**
+ * Creates a function that will observe the key that is passed to it when called
+ * and delegates to the underlying method.
+ *
+ * @param methodName name of the method to delegate to
+ * @param target @see reactive
+ * @param callback @see reactive
+ */
+function makeKeyObserver(methodName: "has" | "get", target: any, callback: Callback) {
+  return (key: any) => {
+    key = toRaw(key);
+    observeTargetKey(target, key, callback);
+    return possiblyReactive(target[methodName](key), callback);
+  };
+}
+/**
+ * Creates an iterable that will delegate to the underlying iteration method and
+ * observe keys as necessary.
+ *
+ * @param methodName name of the method to delegate to
+ * @param target @see reactive
+ * @param callback @see reactive
+ */
+function makeIteratorObserver(
+  methodName: "keys" | "values" | "entries" | typeof Symbol.iterator,
+  target: any,
+  callback: Callback
+) {
+  return function* () {
+    observeTargetKey(target, KEYCHANGES, callback);
+    const keys = target.keys();
+    for (const item of target[methodName]()) {
+      const key = keys.next().value;
+      observeTargetKey(target, key, callback);
+      yield possiblyReactive(item, callback);
+    }
+  };
+}
+/**
+ * Creates a forEach function that will delegate to forEach on the underlying
+ * collection while observing key changes, and keys as they're iterated over,
+ * and making the passed keys/values reactive.
+ *
+ * @param target @see reactive
+ * @param callback @see reactive
+ */
+function makeForEachObserver(target: any, callback: Callback) {
+  return function forEach(forEachCb: (val: any, key: any, target: any) => void, thisArg: any) {
+    observeTargetKey(target, KEYCHANGES, callback);
+    target.forEach(function (val: any, key: any, targetObj: any) {
+      observeTargetKey(target, key, callback);
+      forEachCb.call(
+        thisArg,
+        possiblyReactive(val, callback),
+        possiblyReactive(key, callback),
+        possiblyReactive(targetObj, callback)
+      );
+    }, thisArg);
+  };
+}
+/**
+ * Creates a function that will delegate to an underlying method, and check if
+ * that method has modified the presence or value of a key, and notify the
+ * reactives appropriately.
+ *
+ * @param setterName name of the method to delegate to
+ * @param getterName name of the method which should be used to retrieve the
+ *  value before calling the delegate method for comparison purposes
+ * @param target @see reactive
+ */
+function delegateAndNotify(
+  setterName: "set" | "add" | "delete",
+  getterName: "has" | "get",
+  target: any
+) {
+  return (key: any, value: any) => {
+    key = toRaw(key);
+    const hadKey = target.has(key);
+    const originalValue = target[getterName](key);
+    const ret = target[setterName](key, value);
+    const hasKey = target.has(key);
+    if (hadKey !== hasKey) {
+      notifyReactives(target, KEYCHANGES);
+    }
+    if (originalValue !== value) {
+      notifyReactives(target, key);
+    }
+    return ret;
+  };
+}
+/**
+ * Creates a function that will clear the underlying collection and notify that
+ * the keys of the collection have changed.
+ *
+ * @param target @see reactive
+ */
+function makeClearNotifier(target: Map<any, any> | Set<any>) {
+  return () => {
+    const allKeys = [...target.keys()];
+    target.clear();
+    notifyReactives(target, KEYCHANGES);
+    for (const key of allKeys) {
+      notifyReactives(target, key);
+    }
+  };
+}
+/**
+ * Maps raw type of an object to an object containing functions that can be used
+ * to build an appropritate proxy handler for that raw type. Eg: when making a
+ * reactive set, calling the has method should mark the key that is being
+ * retrieved as observed, and calling the add or delete method should notify the
+ * reactives that the key which is being added or deleted has been modified.
+ */
+const rawTypeToFuncHandlers = {
+  Set: (target: any, callback: Callback) => ({
+    has: makeKeyObserver("has", target, callback),
+    add: delegateAndNotify("add", "has", target),
+    delete: delegateAndNotify("delete", "has", target),
+    keys: makeIteratorObserver("keys", target, callback),
+    values: makeIteratorObserver("values", target, callback),
+    entries: makeIteratorObserver("entries", target, callback),
+    [Symbol.iterator]: makeIteratorObserver(Symbol.iterator, target, callback),
+    forEach: makeForEachObserver(target, callback),
+    clear: makeClearNotifier(target),
+    get size() {
+      observeTargetKey(target, KEYCHANGES, callback);
+      return target.size;
+    },
+  }),
+  Map: (target: any, callback: Callback) => ({
+    has: makeKeyObserver("has", target, callback),
+    get: makeKeyObserver("get", target, callback),
+    set: delegateAndNotify("set", "get", target),
+    delete: delegateAndNotify("delete", "has", target),
+    keys: makeIteratorObserver("keys", target, callback),
+    values: makeIteratorObserver("values", target, callback),
+    entries: makeIteratorObserver("entries", target, callback),
+    [Symbol.iterator]: makeIteratorObserver(Symbol.iterator, target, callback),
+    forEach: makeForEachObserver(target, callback),
+    clear: makeClearNotifier(target),
+    get size() {
+      observeTargetKey(target, KEYCHANGES, callback);
+      return target.size;
+    },
+  }),
+  WeakMap: (target: any, callback: Callback) => ({
+    has: makeKeyObserver("has", target, callback),
+    get: makeKeyObserver("get", target, callback),
+    set: delegateAndNotify("set", "get", target),
+    delete: delegateAndNotify("delete", "has", target),
+  }),
+};
+/**
+ * Creates a proxy handler for collections (Set/Map/WeakMap)
+ *
+ * @param callback @see reactive
+ * @param target @see reactive
+ * @returns a proxy handler object
+ */
+function collectionsProxyHandler<T extends Collection>(
+  target: T,
+  callback: Callback,
+  targetRawType: CollectionRawType
+): ProxyHandler<T> {
+  // TODO: if performance is an issue we can create the special handlers lazily when each
+  // property is read.
+  const specialHandlers = rawTypeToFuncHandlers[targetRawType](target, callback);
+  return Object.assign(basicProxyHandler(callback), {
+    get(target: any, key: PropertyKey) {
+      if (key === TARGET) {
+        return target;
+      }
+      if (objectHasOwnProperty.call(specialHandlers, key)) {
+        return (specialHandlers as any)[key];
+      }
+      observeTargetKey(target, key, callback);
+      return possiblyReactive(target[key], callback);
+    },
+  }) as ProxyHandler<T>;
+}
@@ -0,0 +1,76 @@
+import { fibersInError } from "./error_handling";
+import { Fiber, RootFiber } from "./fibers";
+import { STATUS } from "./status";
+
+// -----------------------------------------------------------------------------
+//  Scheduler
+// -----------------------------------------------------------------------------
+
+export class Scheduler {
+  // capture the value of requestAnimationFrame as soon as possible, to avoid
+  // interactions with other code, such as test frameworks that override them
+  static requestAnimationFrame = window.requestAnimationFrame.bind(window);
+  tasks: Set<RootFiber> = new Set();
+  requestAnimationFrame: Window["requestAnimationFrame"];
+  frame: number = 0;
+  delayedRenders: Fiber[] = [];
+
+  constructor() {
+    this.requestAnimationFrame = Scheduler.requestAnimationFrame;
+  }
+
+  addFiber(fiber: Fiber) {
+    this.tasks.add(fiber.root!);
+  }
+
+  /**
+   * Process all current tasks. This only applies to the fibers that are ready.
+   * Other tasks are left unchanged.
+   */
+  flush() {
+    if (this.delayedRenders.length) {
+      let renders = this.delayedRenders;
+      this.delayedRenders = [];
+      for (let f of renders) {
+        if (f.root && f.node.status !== STATUS.DESTROYED && f.node.fiber === f) {
+          f.render();
+        }
+      }
+    }
+
+    if (this.frame === 0) {
+      this.frame = this.requestAnimationFrame(() => {
+        this.frame = 0;
+        this.tasks.forEach((fiber) => this.processFiber(fiber));
+        for (let task of this.tasks) {
+          if (task.node.status === STATUS.DESTROYED) {
+            this.tasks.delete(task);
+          }
+        }
+      });
+    }
+  }
+
+  processFiber(fiber: RootFiber) {
+    if (fiber.root !== fiber) {
+      this.tasks.delete(fiber);
+      return;
+    }
+    const hasError = fibersInError.has(fiber);
+    if (hasError && fiber.counter !== 0) {
+      this.tasks.delete(fiber);
+      return;
+    }
+    if (fiber.node.status === STATUS.DESTROYED) {
+      this.tasks.delete(fiber);
+      return;
+    }
+
+    if (fiber.counter === 0) {
+      if (!hasError) {
+        fiber.complete();
+      }
+      this.tasks.delete(fiber);
+    }
+  }
+}
@@ -1,7 +1,10 @@
-import { BDom, multi, text, toggler } from "../blockdom";
-import { validateProps } from "../component/props_validation";
-import { Markup } from "../utils";
-import { html } from "../blockdom/index";
+import { BDom, multi, text, toggler, createCatcher } from "./blockdom";
+import { Markup } from "./utils";
+import { html } from "./blockdom/index";
+import { isOptional, validateSchema } from "./validation";
+import type { ComponentConstructor } from "./component";
+import { markRaw } from "./reactivity";
+
 /**
 * This file contains utility functions that will be injected in each template,
 * to perform various useful tasks in the compiled code.
@@ -21,11 +24,11 @@ function callSlot(
  defaultContent?: (ctx: any, node: any, key: string) => BDom
 ): BDom {
  key = key + "__slot_" + name;
-  const slots = (ctx.props && ctx.props.slots) || {};
+  const slots = ctx.props.slots || {};
  const { __render, __ctx, __scope } = slots[name] || {};
  const slotScope = Object.create(__ctx || {});
  if (__scope) {
-    slotScope[__scope] = extra || {};
+    slotScope[__scope] = extra;
  }
  const slotBDom = __render ? __render.call(__ctx.__owl__.component, slotScope, parent, key) : null;
  if (defaultContent) {
@@ -129,19 +132,30 @@ export function safeOutput(value: any): ReturnType<typeof toggler> {
  }
  let safeKey;
  let block;
-  if (value instanceof Markup) {
-    safeKey = `string_safe`;
-    block = html(value as string);
-  } else if (value instanceof LazyValue) {
-    safeKey = `lazy_value`;
-    block = value.evaluate();
-  } else if (typeof value === "string") {
-    safeKey = "string_unsafe";
-    block = text(value);
-  } else {
-    // Assuming it is a block
-    safeKey = "block_safe";
-    block = value;
+  switch (typeof value) {
+    case "object":
+      if (value instanceof Markup) {
+        safeKey = `string_safe`;
+        block = html(value as string);
+      } else if (value instanceof LazyValue) {
+        safeKey = `lazy_value`;
+        block = value.evaluate();
+      } else if (value instanceof String) {
+        safeKey = "string_unsafe";
+        block = text(value);
+      } else {
+        // Assuming it is a block
+        safeKey = "block_safe";
+        block = value;
+      }
+      break;
+    case "string":
+      safeKey = "string_unsafe";
+      block = text(value);
+      break;
+    default:
+      safeKey = "string_unsafe";
+      block = text(String(value));
  }
  return toggler(safeKey, block);
 }
@@ -181,7 +195,53 @@ function multiRefSetter(refs: RefMap, name: string): RefSetter {
  };
 }

-export const UTILS = {
+/**
+ * Validate the component props (or next props) against the (static) props
+ * description.  This is potentially an expensive operation: it may needs to
+ * visit recursively the props and all the children to check if they are valid.
+ * This is why it is only done in 'dev' mode.
+ */
+export function validateProps<P>(name: string | ComponentConstructor<P>, props: P, parent?: any) {
+  const ComponentClass =
+    typeof name !== "string"
+      ? name
+      : (parent.constructor.components[name] as ComponentConstructor<P> | undefined);
+
+  if (!ComponentClass) {
+    // this is an error, wrong component. We silently return here instead so the
+    // error is triggered by the usual path ('component' function)
+    return;
+  }
+
+  const schema = ComponentClass.props;
+  if (!schema) {
+    if (parent.__owl__.app.warnIfNoStaticProps) {
+      console.warn(`Component '${ComponentClass.name}' does not have a static props description`);
+    }
+    return;
+  }
+  const defaultProps = ComponentClass.defaultProps;
+  if (defaultProps) {
+    let isMandatory = (name: string) =>
+      Array.isArray(schema)
+        ? schema.includes(name)
+        : name in schema && !("*" in schema) && !isOptional(schema[name]);
+    for (let p in defaultProps) {
+      if (isMandatory(p)) {
+        throw new Error(
+          `A default value cannot be defined for a mandatory prop (name: '${p}', component: ${ComponentClass.name})`
+        );
+      }
+    }
+  }
+
+  const errors = validateSchema(props, schema);
+  if (errors.length) {
+    throw new Error(`Invalid props for component '${ComponentClass.name}': ` + errors.join(", "));
+  }
+}
+
+export const helpers = {
  withDefault,
  zero: Symbol("zero"),
  isBoundary,
@@ -197,4 +257,6 @@ export const UTILS = {
  LazyValue,
  safeOutput,
  bind,
+  createCatcher,
+  markRaw,
 };
@@ -1,12 +1,11 @@
-import { createBlock, html, list, multi, text, toggler, comment } from "../blockdom";
-import { compile, Template } from "../compiler";
-import { component } from "../component/component_node";
-import { UTILS } from "./template_helpers";
+import { createBlock, html, list, multi, text, toggler, comment } from "./blockdom";
+import { compile, Template, TemplateFunction } from "../compiler";
+import { Portal, portalTemplate } from "./portal";
+import { component, getCurrent } from "./component_node";
+import { helpers } from "./template_helpers";

 const bdom = { text, createBlock, list, multi, html, toggler, component, comment };

-export const globalTemplates: { [key: string]: string | Node } = {};
-
 function parseXML(xml: string): Document {
  const parser = new DOMParser();

@@ -45,18 +44,15 @@ export interface TemplateSetConfig {
 }

 export class TemplateSet {
+  static registerTemplate(name: string, fn: TemplateFunction) {
+    globalTemplates[name] = fn;
+  }
  dev: boolean;
  rawTemplates: typeof globalTemplates = Object.create(globalTemplates);
  templates: { [name: string]: Template } = {};
  translateFn?: (s: string) => string;
  translatableAttributes?: string[];
-  utils: typeof UTILS = Object.assign({}, UTILS, {
-    call: (owner: any, subTemplate: string, ctx: any, parent: any, key: any) => {
-      const template = this.getTemplate(subTemplate);
-      return toggler(subTemplate, template.call(owner, ctx, parent, key));
-    },
-    getTemplate: (name: string, nameSpace?: string) => this.getTemplate(name, nameSpace),
-  });
+  Portal = Portal;

  constructor(config: TemplateSetConfig = {}) {
    this.dev = config.dev || false;
@@ -67,14 +63,25 @@ export class TemplateSet {
    }
  }

-  addTemplate(name: string, template: string | Node, options: { allowDuplicate?: boolean } = {}) {
-    if (name in this.rawTemplates && !options.allowDuplicate) {
-      throw new Error(`Template ${name} already defined`);
+  addTemplate(name: string, template: string | Element) {
+    if (name in this.rawTemplates) {
+      const rawTemplate = this.rawTemplates[name];
+      const currentAsString =
+        typeof rawTemplate === "string"
+          ? rawTemplate
+          : rawTemplate instanceof Element
+          ? rawTemplate.outerHTML
+          : rawTemplate.toString();
+      const newAsString = typeof template === "string" ? template : template.outerHTML;
+      if (currentAsString === newAsString) {
+        return;
+      }
+      throw new Error(`Template ${name} already defined with different content`);
    }
    this.rawTemplates[name] = template;
  }

-  addTemplates(xml: string | Document, options: { allowDuplicate?: boolean } = {}) {
+  addTemplates(xml: string | Document) {
    if (!xml) {
      // empty string
      return;
@@ -82,47 +89,50 @@ export class TemplateSet {
    xml = xml instanceof Document ? xml : parseXML(xml);
    for (const template of xml.querySelectorAll("[t-name]")) {
      const name = template.getAttribute("t-name")!;
-      template.removeAttribute("t-name");
-      this.addTemplate(name, template, options);
+      this.addTemplate(name, template);
    }
  }

-  getTemplate(name: string, nameSpace?: string): Template {
-
+  getTemplate(name: string): Template {
    if (!(name in this.templates)) {
      const rawTemplate = this.rawTemplates[name];
      if (rawTemplate === undefined) {
-        throw new Error(`Missing template: "${name}"`);
+        let extraInfo = "";
+        try {
+          const componentName = getCurrent().component.constructor.name;
+          extraInfo = ` (for component "${componentName}")`;
+        } catch {}
+        throw new Error(`Missing template: "${name}"${extraInfo}`);
      }
-          console.log("getTemplate", nameSpace);
-      const templateFn = this._compileTemplate(name, rawTemplate, nameSpace);
+      const isFn = typeof rawTemplate === "function" && !(rawTemplate instanceof Element);
+      const templateFn = isFn ? rawTemplate : this._compileTemplate(name, rawTemplate);
      // first add a function to lazily get the template, in case there is a
      // recursive call to the template name
      const templates = this.templates;
      this.templates[name] = function (context, parent) {
        return templates[name].call(this, context, parent);
      };
-      const template = templateFn(bdom, this.utils);
+      const template = templateFn(this, bdom, helpers);
      this.templates[name] = template;
    }
    return this.templates[name];
  }

-  _compileTemplate(name: string, template: string | Node, nameSpace?: string) {
-    console.log("CompileTpm", nameSpace)
-    return compile(template, {
-      name,
-      dev: this.dev,
-      translateFn: this.translateFn,
-      translatableAttributes: this.translatableAttributes,
-      nameSpace: nameSpace,
-    });
+  _compileTemplate(name: string, template: string | Element): ReturnType<typeof compile> {
+    throw new Error(`Unable to compile a template. Please use owl full build instead`);
+  }
+
+  callTemplate(owner: any, subTemplate: string, ctx: any, parent: any, key: any): any {
+    const template = this.getTemplate(subTemplate);
+    return toggler(subTemplate, template.call(owner, ctx, parent, key));
  }
 }

 // -----------------------------------------------------------------------------
 //  xml tag helper
 // -----------------------------------------------------------------------------
+export const globalTemplates: { [key: string]: string | Element | TemplateFunction } = {};
+
 export function xml(...args: Parameters<typeof String.raw>) {
  const name = `__template__${xml.nextId++}`;
  const value = String.raw(...args);
@@ -131,3 +141,5 @@ export function xml(...args: Parameters<typeof String.raw>) {
 }

 xml.nextId = 1;
+
+TemplateSet.registerTemplate("__portal__", portalTemplate);
@@ -15,15 +15,26 @@ export function batched(callback: Callback): Callback {
    await Promise.resolve();
    if (!called) {
      called = true;
-      callback();
      // wait for all calls in this microtick to fall through before resetting "called"
-      // so that only the first call to the batched function calls the original callback
-      await Promise.resolve();
-      called = false;
+      // so that only the first call to the batched function calls the original callback.
+      // Schedule this before calling the callback so that calls to the batched function
+      // within the callback will proceed only after resetting called to false, and have
+      // a chance to execute the callback again
+      Promise.resolve().then(() => (called = false));
+      callback();
    }
  };
 }

+export function validateTarget(target: HTMLElement) {
+  if (!(target instanceof HTMLElement)) {
+    throw new Error("Cannot mount component: the target is not a valid DOM element");
+  }
+  if (!document.body.contains(target)) {
+    throw new Error("Cannot mount a component on a detached dom node");
+  }
+}
+
 export class EventBus extends EventTarget {
  trigger(name: string, payload?: any) {
    this.dispatchEvent(new CustomEvent(name, { detail: payload }));
@@ -0,0 +1,161 @@
+type BaseType =
+  | typeof String
+  | typeof Boolean
+  | typeof Number
+  | typeof Date
+  | typeof Object
+  | typeof Array
+  | true
+  | "*";
+
+type UnionType = (TypeInfo | BaseType)[];
+type TypeDescription = BaseType | UnionType | TypeInfo;
+
+interface TypeInfo {
+  type?: TypeDescription;
+  optional?: boolean;
+  validate?: Function;
+  shape?: Schema;
+  element?: TypeDescription;
+}
+
+type SimplifiedSchema = string[];
+type NormalizedSchema = { [key: string]: TypeDescription };
+export type Schema = SimplifiedSchema | NormalizedSchema;
+
+// -----------------------------------------------------------------------------
+// helpers
+// -----------------------------------------------------------------------------
+const isUnionType = (t: TypeDescription): t is UnionType => Array.isArray(t);
+const isBaseType = (t: TypeDescription): t is BaseType => typeof t !== "object";
+
+export function isOptional(t: TypeDescription): Boolean {
+  return typeof t === "object" && "optional" in t ? t.optional || false : false;
+}
+
+function describeType(type: BaseType): string {
+  return type === "*" || type === true ? "value" : type.name.toLowerCase();
+}
+
+function describe(info: TypeDescription): string {
+  if (isBaseType(info)) {
+    return describeType(info);
+  } else if (isUnionType(info)) {
+    return info.map(describe).join(" or ");
+  }
+  if ("element" in info) {
+    return `list of ${describe({ type: info.element, optional: false })}s`;
+  }
+  if ("shape" in (info as TypeInfo)) {
+    return `object`;
+  }
+  return describe(info.type || "*");
+}
+
+function toSchema(spec: SimplifiedSchema): NormalizedSchema {
+  return Object.fromEntries(
+    spec.map((e) =>
+      e.endsWith("?") ? [e.slice(0, -1), { optional: true }] : [e, { type: "*", optional: false }]
+    )
+  );
+}
+
+/**
+ * Main validate function
+ */
+export function validate(obj: { [key: string]: any }, spec: Schema) {
+  let errors = validateSchema(obj, spec);
+  if (errors.length) {
+    throw new Error("Invalid object: " + errors.join(", "));
+  }
+}
+
+/**
+ * Helper validate function, to get the list of errors. useful if one want to
+ * manipulate the errors without parsing an error object
+ */
+export function validateSchema(obj: { [key: string]: any }, schema: Schema): string[] {
+  if (Array.isArray(schema)) {
+    schema = toSchema(schema);
+  }
+  let errors = [];
+  // check if each value in obj has correct shape
+  for (let key in obj) {
+    if (key in schema) {
+      let result = validateType(key, obj[key], schema[key]);
+      if (result) {
+        errors.push(result);
+      }
+    } else if (!("*" in schema)) {
+      errors.push(`unknown key '${key}'`);
+    }
+  }
+  // check that all specified keys are defined in obj
+  for (let key in schema) {
+    const spec = schema[key];
+    if (key !== "*" && !isOptional(spec) && !(key in obj)) {
+      const isObj = typeof spec === "object" && !Array.isArray(spec);
+      const isAny = spec === "*" || (isObj && "type" in spec ? spec.type === "*" : isObj);
+      let detail = isAny ? "" : ` (should be a ${describe(spec)})`;
+      errors.push(`'${key}' is missing${detail}`);
+    }
+  }
+  return errors;
+}
+
+function validateBaseType(key: string, value: any, type: BaseType): string | null {
+  if (typeof type === "function") {
+    if (typeof value === "object") {
+      if (!(value instanceof type)) {
+        return `'${key}' is not a ${describeType(type)}`;
+      }
+    } else if (typeof value !== type.name.toLowerCase()) {
+      return `'${key}' is not a ${describeType(type)}`;
+    }
+  }
+  return null;
+}
+
+function validateArrayType(key: string, value: any, descr: TypeDescription): string | null {
+  if (!Array.isArray(value)) {
+    return `'${key}' is not a list of ${describe(descr)}s`;
+  }
+  for (let i = 0; i < value.length; i++) {
+    const error = validateType(`${key}[${i}]`, value[i], descr);
+    if (error) {
+      return error;
+    }
+  }
+  return null;
+}
+
+function validateType(key: string, value: any, descr: TypeDescription): string | null {
+  if (value === undefined) {
+    return isOptional(descr) ? null : `'${key}' is undefined (should be a ${describe(descr)})`;
+  } else if (isBaseType(descr)) {
+    return validateBaseType(key, value, descr);
+  } else if (isUnionType(descr)) {
+    let validDescr = descr.find((p) => !validateType(key, value, p));
+    return validDescr ? null : `'${key}' is not a ${describe(descr)}`;
+  }
+  let result: string | null = null;
+  if ("element" in descr) {
+    result = validateArrayType(key, value, descr.element!);
+  } else if ("shape" in descr && !result) {
+    if (typeof value !== "object" || Array.isArray(value)) {
+      result = `'${key}' is not an object`;
+    } else {
+      const errors = validateSchema(value, descr.shape!);
+      if (errors.length) {
+        result = `'${key}' has not the correct shape (${errors.join(", ")})`;
+      }
+    }
+  }
+  if ("type" in descr && !result) {
+    result = validateType(key, value, descr.type!);
+  }
+  if ("validate" in descr && !result) {
+    result = !descr.validate!(value) ? `'${key}' is not valid` : null;
+  }
+  return result;
+}
@@ -47,7 +47,7 @@ exports[`Reactivity: useState concurrent renderings 3`] = `
 `;

 exports[`Reactivity: useState destroyed component before being mounted is inactive 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -64,7 +64,7 @@ exports[`Reactivity: useState destroyed component before being mounted is inacti
 `;

 exports[`Reactivity: useState destroyed component before being mounted is inactive 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -78,7 +78,7 @@ exports[`Reactivity: useState destroyed component before being mounted is inacti
 `;

 exports[`Reactivity: useState destroyed component is inactive 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -95,7 +95,7 @@ exports[`Reactivity: useState destroyed component is inactive 1`] = `
 `;

 exports[`Reactivity: useState destroyed component is inactive 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -109,7 +109,7 @@ exports[`Reactivity: useState destroyed component is inactive 2`] = `
 `;

 exports[`Reactivity: useState one components can subscribe twice to same context 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -124,14 +124,14 @@ exports[`Reactivity: useState one components can subscribe twice to same context
 `;

 exports[`Reactivity: useState parent and children subscribed to same context 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
  let block1 = createBlock(\`<div><block-child-0/><block-text-0/></div>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    const b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
    let txt1 = ctx['contextObj'].b;
    return block1([txt1], [b2]);
  }
@@ -139,7 +139,7 @@ exports[`Reactivity: useState parent and children subscribed to same context 1`]
 `;

 exports[`Reactivity: useState parent and children subscribed to same context 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -216,22 +216,22 @@ exports[`Reactivity: useState several nodes on different level use same context
 `;

 exports[`Reactivity: useState two components are updated in parallel 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
  let block1 = createBlock(\`<div><block-child-0/><block-child-1/></div>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
-    let b3 = component(\`Child\`, {}, key + \`__2\`, node, ctx);
+    const b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    const b3 = component(\`Child\`, {}, key + \`__2\`, node, ctx);
    return block1([], [b2, b3]);
  }
 }"
 `;

 exports[`Reactivity: useState two components are updated in parallel 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -245,22 +245,22 @@ exports[`Reactivity: useState two components are updated in parallel 2`] = `
 `;

 exports[`Reactivity: useState two components can subscribe to same context 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
  let block1 = createBlock(\`<div><block-child-0/><block-child-1/></div>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
-    let b3 = component(\`Child\`, {}, key + \`__2\`, node, ctx);
+    const b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    const b3 = component(\`Child\`, {}, key + \`__2\`, node, ctx);
    return block1([], [b2, b3]);
  }
 }"
 `;

 exports[`Reactivity: useState two components can subscribe to same context 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -274,22 +274,22 @@ exports[`Reactivity: useState two components can subscribe to same context 2`] =
 `;

 exports[`Reactivity: useState two independent components on different levels are updated in parallel 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
  let block1 = createBlock(\`<div><block-child-0/><block-child-1/></div>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
-    let b3 = component(\`Parent\`, {}, key + \`__2\`, node, ctx);
+    const b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    const b3 = component(\`Parent\`, {}, key + \`__2\`, node, ctx);
    return block1([], [b2, b3]);
  }
 }"
 `;

 exports[`Reactivity: useState two independent components on different levels are updated in parallel 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -303,21 +303,21 @@ exports[`Reactivity: useState two independent components on different levels are
 `;

 exports[`Reactivity: useState two independent components on different levels are updated in parallel 3`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
  let block1 = createBlock(\`<div><block-child-0/></div>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    const b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`Reactivity: useState useContext=useState hook is reactive, for one component 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -331,7 +331,7 @@ exports[`Reactivity: useState useContext=useState hook is reactive, for one comp
 `;

 exports[`Reactivity: useState useless atoms should be deleted 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { prepareList, withKey } = helpers;
@@ -340,14 +340,14 @@ exports[`Reactivity: useState useless atoms should be deleted 1`] = `
  
  return function template(ctx, node, key = \\"\\") {
    ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(Object.keys(ctx['state']));
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(Object.keys(ctx['state']));;
    for (let i1 = 0; i1 < l_block2; i1++) {
      ctx[\`id\`] = v_block2[i1];
-      let key1 = ctx['id'];
+      const key1 = ctx['id'];
      c_block2[i1] = withKey(component(\`Quantity\`, {id: ctx['id']}, key + \`__1__\${key1}\`, node, ctx), key1);
    }
    ctx = ctx.__proto__;
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
    let txt1 = ctx['total'];
    let txt2 = Object.keys(ctx['state']).length;
    return block1([txt1, txt2], [b2]);
@@ -356,7 +356,7 @@ exports[`Reactivity: useState useless atoms should be deleted 1`] = `
 `;

 exports[`Reactivity: useState useless atoms should be deleted 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -370,7 +370,7 @@ exports[`Reactivity: useState useless atoms should be deleted 2`] = `
 `;

 exports[`Reactivity: useState very simple use, with initial value 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -1,7 +1,7 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP

 exports[`app App supports env with getters/setters 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -16,7 +16,7 @@ exports[`app App supports env with getters/setters 1`] = `
 `;

 exports[`app can configure an app with props 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -30,7 +30,7 @@ exports[`app can configure an app with props 1`] = `
 `;

 exports[`app destroy remove the widget from the DOM 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -41,3 +41,17 @@ exports[`app destroy remove the widget from the DOM 1`] = `
  }
 }"
 `;
+
+exports[`app warnIfNoStaticProps works as expected 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block1 = createBlock(\`<div><block-text-0/></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let txt1 = ctx['message'];
+    return block1([txt1]);
+  }
+}"
+`;
@@ -1,5 +1,5 @@
-import { App, Component, xml } from "../../src";
-import { status } from "../../src/component/status";
+import { App, Component, mount, xml } from "../../src";
+import { status } from "../../src/runtime/status";
 import { makeTestFixture, snapshotEverything, nextTick, elem } from "../helpers";

 let fixture: HTMLElement;
@@ -59,4 +59,21 @@ describe("app", () => {
    await app.mount(fixture);
    expect(fixture.innerHTML).toBe("<div>333</div>");
  });
+
+  test("warnIfNoStaticProps works as expected", async () => {
+    let originalconsoleWarn = console.warn;
+    let mockConsoleWarn = jest.fn(() => {});
+    console.warn = mockConsoleWarn;
+
+    class Root extends Component {
+      static template = xml`<div t-esc="message"/>`;
+    }
+
+    await mount(Root, fixture, { dev: true, props: { messge: "hey" }, warnIfNoStaticProps: true });
+
+    console.warn = originalconsoleWarn;
+    expect(mockConsoleWarn).toBeCalledWith(
+      "Component 'Root' does not have a static props description"
+    );
+  });
 });
@@ -1,4 +1,4 @@
-import { createBlock, mount, patch, remove, text } from "../../src/blockdom";
+import { createBlock, mount, patch, remove, text } from "../../src/runtime/blockdom";
 import { makeTestFixture } from "./helpers";

 //------------------------------------------------------------------------------
@@ -1,4 +1,4 @@
-import { mount, patch, createBlock } from "../../src/blockdom";
+import { mount, patch, createBlock } from "../../src/runtime/blockdom";
 import { makeTestFixture } from "./helpers";

 //------------------------------------------------------------------------------
@@ -169,6 +169,27 @@ describe("properties", () => {
    expect(input.value).toBe("potato");
  });

+  test("input with value attribute, and falsy value given", () => {
+    const block = createBlock(`<input block-attribute-0="value"/>`);
+
+    const tree = block([undefined]);
+    mount(tree, fixture);
+    const input = fixture.querySelector("input")!;
+    expect(input.value).toBe("");
+
+    patch(tree, block([null]));
+    expect(input.value).toBe("");
+
+    patch(tree, block([0]));
+    expect(input.value).toBe("0");
+
+    patch(tree, block([""]));
+    expect(input.value).toBe("");
+
+    patch(tree, block([false]));
+    expect(input.value).toBe("");
+  });
+
  test("input type=checkbox with checked attribute", () => {
    // render input with initial value
    const block = createBlock(`<input type="checkbox" block-attribute-0="checked"/>`);
@@ -1,4 +1,4 @@
-import { mount, createBlock, multi, config, patch } from "../../src/blockdom";
+import { mount, createBlock, multi, config, patch } from "../../src/runtime/blockdom";
 // import { defaultHandler, setupMainHandler } from "../../src/bdom/block";
 import { makeTestFixture } from "./helpers";

@@ -1,4 +1,5 @@
-import { createBlock, mount, patch, remove } from "../../src/blockdom";
+import { createBlock, mount, patch, remove } from "../../src/runtime/blockdom";
+import { logStep } from "../helpers";
 import { makeTestFixture } from "./helpers";

 //------------------------------------------------------------------------------
@@ -55,3 +56,15 @@ test("is in dom when callback is called", async () => {

  mount(tree, fixture);
 });
+
+test("callback ref in callback ref with same block", async () => {
+  const block = createBlock('<p block-ref="0"><block-text-1/><block-child-0/></p>');
+  let refFn = (el: HTMLParagraphElement) => logStep(el.outerHTML);
+
+  const child = block([refFn, "child"], []);
+  const parent = block([refFn, "parent"], [child]);
+  mount(parent, fixture);
+
+  expect(fixture.innerHTML).toBe("<p>parent<p>child</p></p>");
+  expect(["<p>child</p>", "<p>parent<p>child</p></p>"]).toBeLogged();
+});
@@ -1,4 +1,4 @@
-import { comment, mount } from "../../src/blockdom";
+import { comment, mount } from "../../src/runtime/blockdom";
 import { makeTestFixture } from "./helpers";

 //------------------------------------------------------------------------------
@@ -0,0 +1,54 @@
+import { config, createBlock, createCatcher, mount } from "../../src/runtime/blockdom";
+import { makeTestFixture } from "./helpers";
+import { mainEventHandler } from "../../src/runtime/event_handling";
+
+//------------------------------------------------------------------------------
+// Setup and helpers
+//------------------------------------------------------------------------------
+
+let fixture: HTMLElement;
+config.mainEventHandler = mainEventHandler;
+
+beforeEach(() => {
+  fixture = makeTestFixture();
+});
+
+afterEach(() => {
+  fixture.remove();
+});
+
+test("simple event catcher", async () => {
+  const catcher = createCatcher({ click: 0 });
+  const block = createBlock("<div></div>");
+  let n = 0;
+  let ctx = {};
+  let handler = [() => n++, ctx];
+  const tree = catcher(block(), [handler]);
+
+  mount(tree, fixture);
+  expect(fixture.innerHTML).toBe("<div></div>");
+
+  expect(fixture.firstChild).toBeInstanceOf(HTMLDivElement);
+  expect(n).toBe(0);
+  (fixture.firstChild as HTMLDivElement).click();
+  expect(n).toBe(1);
+});
+
+test("do not catch events outside of itself", async () => {
+  const catcher = createCatcher({ click: 0 });
+  const childBlock = createBlock("<div></div>");
+  const parentBlock = createBlock("<button><block-child-0/></button>");
+  let n = 0;
+  let ctx = {};
+  let handler = [() => n++, ctx];
+  const tree = parentBlock([], [catcher(childBlock(), [handler])]);
+
+  mount(tree, fixture);
+  expect(fixture.innerHTML).toBe("<button><div></div></button>");
+
+  expect(n).toBe(0);
+  fixture.querySelector("div")!.click();
+  expect(n).toBe(1);
+  fixture.querySelector("button")!.click();
+  expect(n).toBe(1);
+});
@@ -1,4 +1,4 @@
-import { html, mount, patch, text } from "../../src/blockdom";
+import { html, mount, patch, text } from "../../src/runtime/blockdom";
 import { makeTestFixture } from "./helpers";

 //------------------------------------------------------------------------------
@@ -1,4 +1,13 @@
-import { list, mount, multi, patch, text, createBlock, VNode, withKey } from "../../src/blockdom";
+import {
+  list,
+  mount,
+  multi,
+  patch,
+  text,
+  createBlock,
+  VNode,
+  withKey,
+} from "../../src/runtime/blockdom";
 import { makeTestFixture } from "./helpers";

 //------------------------------------------------------------------------------
@@ -1,4 +1,4 @@
-import { mount, multi, patch, text, createBlock } from "../../src/blockdom";
+import { mount, multi, patch, text, createBlock } from "../../src/runtime/blockdom";
 import { makeTestFixture } from "./helpers";

 //------------------------------------------------------------------------------
@@ -1,4 +1,4 @@
-import { createBlock, mount } from "../../src/blockdom";
+import { createBlock, mount } from "../../src/runtime/blockdom";
 import { makeTestFixture } from "./helpers";

 //------------------------------------------------------------------------------
@@ -1,4 +1,4 @@
-import { createBlock, mount, multi, patch } from "../../src/blockdom";
+import { createBlock, mount, multi, patch } from "../../src/runtime/blockdom";
 import { makeTestFixture } from "./helpers";

 //------------------------------------------------------------------------------
@@ -1,4 +1,4 @@
-import { mount, patch, remove, text } from "../../src/blockdom";
+import { mount, patch, remove, text } from "../../src/runtime/blockdom";
 import { makeTestFixture } from "./helpers";

 //------------------------------------------------------------------------------
@@ -1,4 +1,4 @@
-import { createBlock, mount, patch, text, toggler } from "../../src/blockdom";
+import { createBlock, mount, patch, text, toggler } from "../../src/runtime/blockdom";
 import { makeTestFixture } from "./helpers";

 //------------------------------------------------------------------------------
@@ -1,7 +1,7 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP

 exports[`attributes changing a class with t-att-class (preexisting class 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -15,7 +15,7 @@ exports[`attributes changing a class with t-att-class (preexisting class 1`] = `
 `;

 exports[`attributes changing a class with t-att-class 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -29,7 +29,7 @@ exports[`attributes changing a class with t-att-class 1`] = `
 `;

 exports[`attributes changing an attribute with t-att- 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -43,7 +43,7 @@ exports[`attributes changing an attribute with t-att- 1`] = `
 `;

 exports[`attributes class and t-att-class should combine together 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -57,7 +57,7 @@ exports[`attributes class and t-att-class should combine together 1`] = `
 `;

 exports[`attributes class and t-attf-class with ternary operation 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -71,7 +71,7 @@ exports[`attributes class and t-attf-class with ternary operation 1`] = `
 `;

 exports[`attributes dynamic attribute evaluating to 0 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -85,7 +85,7 @@ exports[`attributes dynamic attribute evaluating to 0 1`] = `
 `;

 exports[`attributes dynamic attribute falsy variable  1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -99,7 +99,7 @@ exports[`attributes dynamic attribute falsy variable  1`] = `
 `;

 exports[`attributes dynamic attribute with a dash 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -113,7 +113,7 @@ exports[`attributes dynamic attribute with a dash 1`] = `
 `;

 exports[`attributes dynamic attributes 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -127,7 +127,7 @@ exports[`attributes dynamic attributes 1`] = `
 `;

 exports[`attributes dynamic class attribute 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -141,7 +141,7 @@ exports[`attributes dynamic class attribute 1`] = `
 `;

 exports[`attributes dynamic class attribute evaluating to 0 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -155,7 +155,7 @@ exports[`attributes dynamic class attribute evaluating to 0 1`] = `
 `;

 exports[`attributes dynamic empty class attribute 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -169,7 +169,7 @@ exports[`attributes dynamic empty class attribute 1`] = `
 `;

 exports[`attributes dynamic formatted attributes with a dash 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -183,7 +183,7 @@ exports[`attributes dynamic formatted attributes with a dash 1`] = `
 `;

 exports[`attributes dynamic undefined class attribute 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -197,7 +197,7 @@ exports[`attributes dynamic undefined class attribute 1`] = `
 `;

 exports[`attributes dynamic undefined generic attribute 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -211,7 +211,7 @@ exports[`attributes dynamic undefined generic attribute 1`] = `
 `;

 exports[`attributes fixed variable 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -225,7 +225,7 @@ exports[`attributes fixed variable 1`] = `
 `;

 exports[`attributes format expression 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -239,7 +239,7 @@ exports[`attributes format expression 1`] = `
 `;

 exports[`attributes format literal 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -253,7 +253,7 @@ exports[`attributes format literal 1`] = `
 `;

 exports[`attributes format multiple 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -267,7 +267,7 @@ exports[`attributes format multiple 1`] = `
 `;

 exports[`attributes format value 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -281,7 +281,7 @@ exports[`attributes format value 1`] = `
 `;

 exports[`attributes from object variables set previously 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue } = helpers;
@@ -299,7 +299,7 @@ exports[`attributes from object variables set previously 1`] = `
 `;

 exports[`attributes from variables set previously (no external node) 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue } = helpers;
@@ -317,7 +317,7 @@ exports[`attributes from variables set previously (no external node) 1`] = `
 `;

 exports[`attributes from variables set previously 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue } = helpers;
@@ -335,7 +335,7 @@ exports[`attributes from variables set previously 1`] = `
 `;

 exports[`attributes object 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -349,7 +349,7 @@ exports[`attributes object 1`] = `
 `;

 exports[`attributes static attributes 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -362,7 +362,7 @@ exports[`attributes static attributes 1`] = `
 `;

 exports[`attributes static attributes on void elements 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -375,7 +375,7 @@ exports[`attributes static attributes on void elements 1`] = `
 `;

 exports[`attributes static attributes with dashes 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -387,8 +387,22 @@ exports[`attributes static attributes with dashes 1`] = `
 }"
 `;

+exports[`attributes string interpolation, alternate syntax 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block1 = createBlock(\`<div block-attribute-0=\\"foo\\"/>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let attr1 = \`b\${ctx['value']}r\`;
+    return block1([attr1]);
+  }
+}"
+`;
+
 exports[`attributes t-att-class and class should combine together 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -402,7 +416,7 @@ exports[`attributes t-att-class and class should combine together 1`] = `
 `;

 exports[`attributes t-att-class with multiple classes 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -416,7 +430,7 @@ exports[`attributes t-att-class with multiple classes 1`] = `
 `;

 exports[`attributes t-att-class with multiple classes 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -430,7 +444,7 @@ exports[`attributes t-att-class with multiple classes 2`] = `
 `;

 exports[`attributes t-att-class with multiple classes, some of which are duplicate 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -444,7 +458,7 @@ exports[`attributes t-att-class with multiple classes, some of which are duplica
 `;

 exports[`attributes t-att-class with object 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -458,7 +472,7 @@ exports[`attributes t-att-class with object 1`] = `
 `;

 exports[`attributes t-attf-class 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -472,7 +486,7 @@ exports[`attributes t-attf-class 1`] = `
 `;

 exports[`attributes t-attf-class should combine with class 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -486,7 +500,7 @@ exports[`attributes t-attf-class should combine with class 1`] = `
 `;

 exports[`attributes t-attf-class with multiple classes 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -500,7 +514,7 @@ exports[`attributes t-attf-class with multiple classes 1`] = `
 `;

 exports[`attributes t-attf-class with multiple classes separated by multiple spaces 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -514,7 +528,7 @@ exports[`attributes t-attf-class with multiple classes separated by multiple spa
 `;

 exports[`attributes tuple literal 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -528,7 +542,7 @@ exports[`attributes tuple literal 1`] = `
 `;

 exports[`attributes tuple variable 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -542,7 +556,7 @@ exports[`attributes tuple variable 1`] = `
 `;

 exports[`attributes two classes 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -555,7 +569,7 @@ exports[`attributes two classes 1`] = `
 `;

 exports[`attributes two dynamic attributes 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -570,7 +584,7 @@ exports[`attributes two dynamic attributes 1`] = `
 `;

 exports[`attributes updating classes (with obj notation) 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -584,7 +598,7 @@ exports[`attributes updating classes (with obj notation) 1`] = `
 `;

 exports[`attributes various escapes 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -600,7 +614,7 @@ exports[`attributes various escapes 1`] = `
 `;

 exports[`attributes various escapes 2 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -613,7 +627,7 @@ exports[`attributes various escapes 2 1`] = `
 `;

 exports[`special cases for some specific html attributes/properties input of type checkbox with t-att-indeterminate 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -627,7 +641,7 @@ exports[`special cases for some specific html attributes/properties input of typ
 `;

 exports[`special cases for some specific html attributes/properties input type= checkbox, with t-att-checked 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -641,7 +655,7 @@ exports[`special cases for some specific html attributes/properties input type=
 `;

 exports[`special cases for some specific html attributes/properties input with t-att-value 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -655,7 +669,7 @@ exports[`special cases for some specific html attributes/properties input with t
 `;

 exports[`special cases for some specific html attributes/properties select with t-att-value 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -669,7 +683,7 @@ exports[`special cases for some specific html attributes/properties select with
 `;

 exports[`special cases for some specific html attributes/properties textarea with t-att-value 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -683,7 +697,7 @@ exports[`special cases for some specific html attributes/properties textarea wit
 `;

 exports[`special cases for some specific html attributes/properties various boolean html attributes 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -1,7 +1,7 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP

 exports[`comments only a comment 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -12,7 +12,7 @@ exports[`comments only a comment 1`] = `
 `;

 exports[`comments properly handle comments 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -25,7 +25,7 @@ exports[`comments properly handle comments 1`] = `
 `;

 exports[`comments properly handle comments between t-if/t-else 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -1,7 +1,7 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP

 exports[`t-on can bind event handler 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -15,7 +15,7 @@ exports[`t-on can bind event handler 1`] = `
 `;

 exports[`t-on can bind handlers with arguments 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -30,7 +30,7 @@ exports[`t-on can bind handlers with arguments 1`] = `
 `;

 exports[`t-on can bind handlers with empty  object 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -45,7 +45,7 @@ exports[`t-on can bind handlers with empty  object 1`] = `
 `;

 exports[`t-on can bind handlers with empty object (with non empty inner string) 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -60,7 +60,7 @@ exports[`t-on can bind handlers with empty object (with non empty inner string)
 `;

 exports[`t-on can bind handlers with empty object (with non empty inner string) 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { prepareList, withKey } = helpers;
@@ -70,24 +70,24 @@ exports[`t-on can bind handlers with empty object (with non empty inner string)
  
  return function template(ctx, node, key = \\"\\") {
    ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(['someval']);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(['someval']);;
    for (let i1 = 0; i1 < l_block2; i1++) {
      ctx[\`action\`] = v_block2[i1];
      ctx[\`action_index\`] = i1;
-      let key1 = ctx['action_index'];
+      const key1 = ctx['action_index'];
      const v1 = ctx['activate'];
      const v2 = ctx['action'];
      let hdlr1 = [()=>v1(v2), ctx];
      c_block2[i1] = withKey(block3([hdlr1]), key1);
    }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-on can bind handlers with object arguments 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -102,7 +102,7 @@ exports[`t-on can bind handlers with object arguments 1`] = `
 `;

 exports[`t-on can bind two event handlers 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -117,7 +117,7 @@ exports[`t-on can bind two event handlers 1`] = `
 `;

 exports[`t-on handler is bound to proper owner 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -131,7 +131,7 @@ exports[`t-on handler is bound to proper owner 1`] = `
 `;

 exports[`t-on handler is bound to proper owner, part 2 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { prepareList, withKey } = helpers;
@@ -140,10 +140,10 @@ exports[`t-on handler is bound to proper owner, part 2 1`] = `
  
  return function template(ctx, node, key = \\"\\") {
    ctx = Object.create(ctx);
-    const [k_block1, v_block1, l_block1, c_block1] = prepareList([1]);
+    const [k_block1, v_block1, l_block1, c_block1] = prepareList([1]);;
    for (let i1 = 0; i1 < l_block1; i1++) {
      ctx[\`value\`] = v_block1[i1];
-      let key1 = ctx['value'];
+      const key1 = ctx['value'];
      let hdlr1 = [ctx['add'], ctx];
      c_block1[i1] = withKey(block2([hdlr1]), key1);
    }
@@ -153,11 +153,10 @@ exports[`t-on handler is bound to proper owner, part 2 1`] = `
 `;

 exports[`t-on handler is bound to proper owner, part 3 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
-  let { getTemplate } = helpers;
-  const callTemplate_1 = getTemplate(\`sub\`);
+  const callTemplate_1 = app.getTemplate(\`sub\`);
  
  return function template(ctx, node, key = \\"\\") {
    return callTemplate_1.call(this, ctx, node, key + \`__1\`);
@@ -166,7 +165,7 @@ exports[`t-on handler is bound to proper owner, part 3 1`] = `
 `;

 exports[`t-on handler is bound to proper owner, part 3 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -180,22 +179,22 @@ exports[`t-on handler is bound to proper owner, part 3 2`] = `
 `;

 exports[`t-on handler is bound to proper owner, part 4 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
-  let { prepareList, getTemplate, withKey } = helpers;
-  const callTemplate_1 = getTemplate(\`sub\`);
+  let { prepareList, withKey } = helpers;
+  const callTemplate_1 = app.getTemplate(\`sub\`);
  
  return function template(ctx, node, key = \\"\\") {
    ctx = Object.create(ctx);
-    const [k_block1, v_block1, l_block1, c_block1] = prepareList([1]);
+    const [k_block1, v_block1, l_block1, c_block1] = prepareList([1]);;
    for (let i1 = 0; i1 < l_block1; i1++) {
      ctx[\`value\`] = v_block1[i1];
      ctx[\`value_first\`] = i1 === 0;
      ctx[\`value_last\`] = i1 === v_block1.length - 1;
      ctx[\`value_index\`] = i1;
      ctx[\`value_value\`] = k_block1[i1];
-      let key1 = ctx['value'];
+      const key1 = ctx['value'];
      c_block1[i1] = withKey(callTemplate_1.call(this, ctx, node, key + \`__1__\${key1}\`), key1);
    }
    return list(c_block1);
@@ -204,7 +203,7 @@ exports[`t-on handler is bound to proper owner, part 4 1`] = `
 `;

 exports[`t-on handler is bound to proper owner, part 4 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -218,7 +217,7 @@ exports[`t-on handler is bound to proper owner, part 4 2`] = `
 `;

 exports[`t-on receive event in first argument 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -232,7 +231,7 @@ exports[`t-on receive event in first argument 1`] = `
 `;

 exports[`t-on t-on modifiers (native listener) basic support for native listener 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -247,7 +246,7 @@ exports[`t-on t-on modifiers (native listener) basic support for native listener
 `;

 exports[`t-on t-on modifiers (native listener) t-on combined with t-esc 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -262,7 +261,7 @@ exports[`t-on t-on modifiers (native listener) t-on combined with t-esc 1`] = `
 `;

 exports[`t-on t-on modifiers (native listener) t-on combined with t-out 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { safeOutput } = helpers;
@@ -271,14 +270,14 @@ exports[`t-on t-on modifiers (native listener) t-on combined with t-out 1`] = `
  
  return function template(ctx, node, key = \\"\\") {
    let hdlr1 = [ctx['onClick'], ctx];
-    let b2 = safeOutput(ctx['html']);
+    const b2 = safeOutput(ctx['html']);
    return block1([hdlr1], [b2]);
  }
 }"
 `;

 exports[`t-on t-on modifiers (native listener) t-on with .capture modifier 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -293,7 +292,7 @@ exports[`t-on t-on modifiers (native listener) t-on with .capture modifier 1`] =
 `;

 exports[`t-on t-on modifiers (native listener) t-on with empty handler (only modifiers) 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -307,7 +306,7 @@ exports[`t-on t-on modifiers (native listener) t-on with empty handler (only mod
 `;

 exports[`t-on t-on modifiers (native listener) t-on with prevent and self modifiers (order matters) 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -321,7 +320,7 @@ exports[`t-on t-on modifiers (native listener) t-on with prevent and self modifi
 `;

 exports[`t-on t-on modifiers (native listener) t-on with prevent and/or stop modifiers 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -337,7 +336,7 @@ exports[`t-on t-on modifiers (native listener) t-on with prevent and/or stop mod
 `;

 exports[`t-on t-on modifiers (native listener) t-on with prevent modifier in t-foreach 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { prepareList, withKey } = helpers;
@@ -347,24 +346,24 @@ exports[`t-on t-on modifiers (native listener) t-on with prevent modifier in t-f
  
  return function template(ctx, node, key = \\"\\") {
    ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['projects']);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['projects']);;
    for (let i1 = 0; i1 < l_block2; i1++) {
      ctx[\`project\`] = v_block2[i1];
-      let key1 = ctx['project'];
+      const key1 = ctx['project'];
      const v1 = ctx['onEdit'];
      const v2 = ctx['project'];
-      let hdlr1 = [\\"prevent\\", ev=>v1(v2.id,ev), ctx];
+      let hdlr1 = [\\"prevent\\", _ev=>v1(v2.id,_ev), ctx];
      let txt1 = ctx['project'].name;
      c_block2[i1] = withKey(block3([hdlr1, txt1]), key1);
    }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-on t-on modifiers (native listener) t-on with self and prevent modifiers (order matters) 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -378,7 +377,7 @@ exports[`t-on t-on modifiers (native listener) t-on with self and prevent modifi
 `;

 exports[`t-on t-on modifiers (native listener) t-on with self modifier 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -393,7 +392,7 @@ exports[`t-on t-on modifiers (native listener) t-on with self modifier 1`] = `
 `;

 exports[`t-on t-on modifiers (synthetic listener) basic support for synthetic 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -408,7 +407,7 @@ exports[`t-on t-on modifiers (synthetic listener) basic support for synthetic 1`
 `;

 exports[`t-on t-on with inline statement (function call) 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -423,7 +422,7 @@ exports[`t-on t-on with inline statement (function call) 1`] = `
 `;

 exports[`t-on t-on with inline statement 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -438,7 +437,7 @@ exports[`t-on t-on with inline statement 1`] = `
 `;

 exports[`t-on t-on with inline statement, part 2 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -453,7 +452,7 @@ exports[`t-on t-on with inline statement, part 2 1`] = `
 `;

 exports[`t-on t-on with inline statement, part 3 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -469,23 +468,22 @@ exports[`t-on t-on with inline statement, part 3 1`] = `
 `;

 exports[`t-on t-on with t-call 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
-  let { getTemplate } = helpers;
-  const callTemplate_1 = getTemplate(\`sub\`);
+  const callTemplate_1 = app.getTemplate(\`sub\`);
  
  let block1 = createBlock(\`<div><block-child-0/></div>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    const b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-on t-on with t-call 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -499,23 +497,22 @@ exports[`t-on t-on with t-call 2`] = `
 `;

 exports[`t-on t-on, with arguments and t-call 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
-  let { getTemplate } = helpers;
-  const callTemplate_1 = getTemplate(\`sub\`);
+  const callTemplate_1 = app.getTemplate(\`sub\`);
  
  let block1 = createBlock(\`<div><block-child-0/></div>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    const b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-on t-on, with arguments and t-call 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -1,7 +1,7 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP

 exports[`misc complex template 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { prepareList, withKey } = helpers;
@@ -30,28 +30,28 @@ exports[`misc complex template 1`] = `
      b3 = block3();
    }
    ctx = Object.create(ctx);
-    const [k_block4, v_block4, l_block4, c_block4] = prepareList(ctx['batch'].slot_ids.filter(slot=>slot.build_id.id&&!slot.trigger_id.manual&&(ctx['options'].trigger_display[slot.trigger_id.id])));
+    const [k_block4, v_block4, l_block4, c_block4] = prepareList(ctx['batch'].slot_ids.filter(_slot=>_slot.build_id.id&&!_slot.trigger_id.manual&&(ctx['options'].trigger_display[_slot.trigger_id.id])));;
    for (let i1 = 0; i1 < l_block4; i1++) {
      ctx[\`slot\`] = v_block4[i1];
-      let key1 = ctx['slot'].id;
+      const key1 = ctx['slot'].id;
      c_block4[i1] = withKey(component(\`SlotButton\`, {class: ctx['slot_container'],slot: ctx['slot']}, key + \`__1__\${key1}\`, node, ctx), key1);
    }
    ctx = ctx.__proto__;
    b4 = list(c_block4);
    ctx = Object.create(ctx);
-    const [k_block6, v_block6, l_block6, c_block6] = prepareList([1,2,3,4]);
+    const [k_block6, v_block6, l_block6, c_block6] = prepareList([1,2,3,4]);;
    for (let i1 = 0; i1 < l_block6; i1++) {
      ctx[\`x\`] = v_block6[i1];
-      let key1 = ctx['x'];
+      const key1 = ctx['x'];
      c_block6[i1] = withKey(block7(), key1);
    }
    ctx = ctx.__proto__;
    b6 = list(c_block6);
    ctx = Object.create(ctx);
-    const [k_block8, v_block8, l_block8, c_block8] = prepareList(ctx['commit_links']);
+    const [k_block8, v_block8, l_block8, c_block8] = prepareList(ctx['commit_links']);;
    for (let i1 = 0; i1 < l_block8; i1++) {
      ctx[\`commit_link\`] = v_block8[i1];
-      let key1 = ctx['commit_link'].id;
+      const key1 = ctx['commit_link'].id;
      let b10,b11,b12,b13;
      let attr5 = \`/runbot/commit/\${ctx['commit_link'].commit_id}\`;
      let attr6 = \`badge badge-light batch_commit match_type_\${ctx['commit_link'].match_type}\`;
@@ -79,15 +79,15 @@ exports[`misc complex template 1`] = `
 `;

 exports[`misc global 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
-  let { prepareList, isBoundary, withDefault, setContextValue, getTemplate, zero, withKey } = helpers;
-  const callTemplate_1 = getTemplate(\`_callee-uses-foo\`);
-  const callTemplate_2 = getTemplate(\`_callee-uses-foo\`);
-  const callTemplate_3 = getTemplate(\`_callee-uses-foo\`);
-  const callTemplate_4 = getTemplate(\`_callee-asc\`);
-  const callTemplate_5 = getTemplate(\`_callee-asc-toto\`);
+  let { prepareList, isBoundary, withDefault, setContextValue, zero, withKey } = helpers;
+  const callTemplate_1 = app.getTemplate(\`_callee-uses-foo\`);
+  const callTemplate_2 = app.getTemplate(\`_callee-uses-foo\`);
+  const callTemplate_3 = app.getTemplate(\`_callee-uses-foo\`);
+  const callTemplate_4 = app.getTemplate(\`_callee-asc\`);
+  const callTemplate_5 = app.getTemplate(\`_callee-asc-toto\`);
  
  let block1 = createBlock(\`<div><block-child-0/><block-child-1/></div>\`);
  let block4 = createBlock(\`<span><block-text-0/></span>\`);
@@ -96,42 +96,42 @@ exports[`misc global 1`] = `
    ctx = Object.create(ctx);
    ctx[isBoundary] = 1
    ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList([4,5,6]);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList([4,5,6]);;
    for (let i1 = 0; i1 < l_block2; i1++) {
      ctx[\`value\`] = v_block2[i1];
      ctx[\`value_first\`] = i1 === 0;
      ctx[\`value_last\`] = i1 === v_block2.length - 1;
      ctx[\`value_index\`] = i1;
      ctx[\`value_value\`] = k_block2[i1];
-      let key1 = ctx['value'];
+      const key1 = ctx['value'];
      let txt1 = ctx['value'];
-      let b4 = block4([txt1]);
+      const b4 = block4([txt1]);
      ctx = Object.create(ctx);
      ctx[isBoundary] = 1;
      ctx = Object.create(ctx);
      ctx[isBoundary] = 1;
      setContextValue(ctx, \\"foo\\", 'aaa');
-      let b6 = callTemplate_1.call(this, ctx, node, key + \`__1__\${key1}\`);
+      const b6 = callTemplate_1.call(this, ctx, node, key + \`__1__\${key1}\`);
      ctx = ctx.__proto__;
-      let b7 = callTemplate_2.call(this, ctx, node, key + \`__2__\${key1}\`);
+      const b7 = callTemplate_2.call(this, ctx, node, key + \`__2__\${key1}\`);
      setContextValue(ctx, \\"foo\\", 'bbb');
-      let b8 = callTemplate_3.call(this, ctx, node, key + \`__3__\${key1}\`);
-      let b5 = multi([b6, b7, b8]);
+      const b8 = callTemplate_3.call(this, ctx, node, key + \`__3__\${key1}\`);
+      const b5 = multi([b6, b7, b8]);
      ctx[zero] = b5;
-      let b9 = callTemplate_4.call(this, ctx, node, key + \`__4__\${key1}\`);
+      const b9 = callTemplate_4.call(this, ctx, node, key + \`__4__\${key1}\`);
      ctx = ctx.__proto__;
      c_block2[i1] = withKey(multi([b4, b9]), key1);
    }
    ctx = ctx.__proto__;
-    let b2 = list(c_block2);
-    let b10 = callTemplate_5.call(this, ctx, node, key + \`__5\`);
+    const b2 = list(c_block2);
+    const b10 = callTemplate_5.call(this, ctx, node, key + \`__5\`);
    return block1([], [b2, b10]);
  }
 }"
 `;

 exports[`misc global 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { withDefault } = helpers;
@@ -146,7 +146,7 @@ exports[`misc global 2`] = `
 `;

 exports[`misc global 3`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { zero } = helpers;
@@ -155,14 +155,14 @@ exports[`misc global 3`] = `
  
  return function template(ctx, node, key = \\"\\") {
    let attr1 = 'agüero';
-    let b2 = ctx[zero];
+    const b2 = ctx[zero];
    return block1([attr1], [b2]);
  }
 }"
 `;

 exports[`misc global 4`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { safeOutput, withDefault } = helpers;
@@ -170,19 +170,19 @@ exports[`misc global 4`] = `
  let block1 = createBlock(\`<div><block-child-0/></div>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b3 = text(\`toto default\`);
-    let b2 = withDefault(safeOutput(ctx['toto']), b3);
+    const b3 = text(\`toto default\`);
+    const b2 = withDefault(safeOutput(ctx['toto']), b3);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`misc other complex template 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
-  let { prepareList, withKey, getTemplate } = helpers;
-  const callTemplate_1 = getTemplate(\`LOAD_INFOS_TEMPLATE\`);
+  let { prepareList, withKey } = helpers;
+  const callTemplate_1 = app.getTemplate(\`LOAD_INFOS_TEMPLATE\`);
  
  let block1 = createBlock(\`<div><header><nav class=\\"navbar navbar-expand-md navbar-light bg-light\\"><a block-attribute-0=\\"href\\"><b style=\\"color:#777;\\"><block-text-1/></b></a><button type=\\"button\\" class=\\"navbar-toggler\\" data-toggle=\\"collapse\\" data-target=\\"#top_menu_collapse\\"><span class=\\"navbar-toggler-icon\\"/></button><div class=\\"collapse navbar-collapse\\" id=\\"top_menu_collapse\\" aria-expanded=\\"false\\"><ul class=\\"nav navbar-nav ml-auto text-right\\" id=\\"top_menu\\"><block-child-0/><li class=\\"nav-item divider\\"/><block-child-1/></ul><div><div class=\\"input-group input-group-sm\\"><div class=\\"input-group-prepend input-group-sm\\"><button class=\\"btn btn-default fa fa-cog\\" title=\\"Settings\\" block-handler-2=\\"click\\"/><button class=\\"btn btn-default\\" block-handler-3=\\"click\\"> More </button><block-child-2/></div><input class=\\"form-control\\" type=\\"text\\" placeholder=\\"Search\\" aria-label=\\"Search\\" name=\\"search\\" block-attribute-4=\\"value\\" block-handler-5=\\"keyup\\" block-handler-6=\\"change\\" block-ref=\\"7\\"/><div class=\\"input-group-append\\"><button class=\\"btn btn-default fa fa-eraser\\" block-handler-8=\\"click\\"/></div></div></div></div></nav></header><div class=\\"container-fluid\\" block-ref=\\"9\\"><div class=\\"row\\"><!--div class=\\"form-group col-md-6\\">
                      <h5>Search options</h5>
@@ -221,10 +221,10 @@ exports[`misc other complex template 1`] = `
    let attr1 = \`/runbot/\${ctx['project'].slug}\`;
    let txt1 = ctx['project'].name;
    ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['projects']);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['projects']);;
    for (let i1 = 0; i1 < l_block2; i1++) {
      ctx[\`project\`] = v_block2[i1];
-      let key1 = ctx['project'].id;
+      const key1 = ctx['project'].id;
      let hdlr1 = [ctx['selectProject'](ctx['project']), ctx];
      let txt2 = ctx['project'].name;
      c_block2[i1] = withKey(block3([hdlr1, txt2]), key1);
@@ -241,12 +241,12 @@ exports[`misc other complex template 1`] = `
        if (ctx['nb_assigned_errors']&&ctx['nb_assigned_errors']>0) {
          let attr3 = \`You have \${ctx['nb_assigned_errors']} random bug assigned\`;
          let txt3 = ctx['nb_assigned_errors'];
-          let b8 = block8([attr3, txt3]);
-          let b9 = block9();
+          const b8 = block8([attr3, txt3]);
+          const b9 = block9();
          b7 = multi([b8, b9]);
        } else if (ctx['nb_build_errors']&&ctx['nb_build_errors']>0) {
-          let b11 = block11();
-          let b12 = block12();
+          const b11 = block11();
+          const b12 = block12();
          b10 = multi([b11, b12]);
        }
        let txt4 = ctx['user'].name.length>25?ctx['user'].namesubstring(0,23)+'...':ctx['user'].name;
@@ -261,17 +261,17 @@ exports[`misc other complex template 1`] = `
    let hdlr3 = [ctx['toggleMore'], ctx];
    if (ctx['categories']&&ctx['categories'].length>1) {
      ctx = Object.create(ctx);
-      const [k_block15, v_block15, l_block15, c_block15] = prepareList(ctx['categories']);
+      const [k_block15, v_block15, l_block15, c_block15] = prepareList(ctx['categories']);;
      for (let i1 = 0; i1 < l_block15; i1++) {
        ctx[\`category\`] = v_block15[i1];
-        let key1 = ctx['category'].id;
+        const key1 = ctx['category'].id;
        let attr6 = ctx['category'].id;
        let attr7 = ctx['category'].id==ctx['options'].active_category_id;
        let txt5 = ctx['category'].name;
        c_block15[i1] = withKey(block16([attr6, attr7, txt5]), key1);
      }
      ctx = ctx.__proto__;
-      let b15 = list(c_block15);
+      const b15 = list(c_block15);
      b14 = block14([], [b15]);
    }
    let attr8 = ctx['search'].value;
@@ -280,10 +280,10 @@ exports[`misc other complex template 1`] = `
    let hdlr6 = [ctx['clearSearch'], ctx];
    if (ctx['triggers']) {
      ctx = Object.create(ctx);
-      const [k_block18, v_block18, l_block18, c_block18] = prepareList(ctx['triggers']);
+      const [k_block18, v_block18, l_block18, c_block18] = prepareList(ctx['triggers']);;
      for (let i1 = 0; i1 < l_block18; i1++) {
        ctx[\`trigger\`] = v_block18[i1];
-        let key1 = ctx['trigger'].id;
+        const key1 = ctx['trigger'].id;
        let b20;
        if (!ctx['trigger'].manual&&ctx['trigger'].project_id===ctx['project'].id&&ctx['trigger'].category_id===ctx['options'].active_category_id) {
          let attr9 = \`trigger_\${ctx['trigger'].id}\`;
@@ -298,12 +298,12 @@ exports[`misc other complex template 1`] = `
        c_block18[i1] = withKey(multi([b20]), key1);
      }
      ctx = ctx.__proto__;
-      let b18 = list(c_block18);
+      const b18 = list(c_block18);
      let hdlr8 = [ctx['triggerAll'], ctx];
      let hdlr9 = [ctx['triggerNone'], ctx];
      let hdlr10 = [ctx['triggerDefault'], ctx];
      let hdlr11 = [ctx['toggleSettingsMenu'], ctx];
-      let b21 = block21([hdlr8, hdlr9, hdlr10, hdlr11]);
+      const b21 = block21([hdlr8, hdlr9, hdlr10, hdlr11]);
      b17 = multi([b18, b21]);
    }
    if (ctx['load_infos']) {
@@ -316,8 +316,8 @@ exports[`misc other complex template 1`] = `
    if (!ctx['project']) {
      b24 = block24();
    } else {
-      let b26 = component(\`BundlesList\`, {bundles: ctx['bundles'].sticky,category_custom_views: ctx['category_custom_views'],search: ctx['search']}, key + \`__2\`, node, ctx);
-      let b27 = component(\`BundlesList\`, {bundles: ctx['bundles'].dev,search: ctx['search']}, key + \`__3\`, node, ctx);
+      const b26 = component(\`BundlesList\`, {bundles: ctx['bundles'].sticky,category_custom_views: ctx['category_custom_views'],search: ctx['search']}, key + \`__2\`, node, ctx);
+      const b27 = component(\`BundlesList\`, {bundles: ctx['bundles'].dev,search: ctx['search']}, key + \`__3\`, node, ctx);
      b25 = block25([], [b26, b27]);
    }
    return block1([attr1, txt1, hdlr2, hdlr3, attr8, hdlr4, hdlr5, ref1, hdlr6, ref2], [b2, b4, b14, b17, b22, b23, b24, b25]);
@@ -1,7 +1,7 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP

 exports[`memory t-foreach does not leak stuff in global scope 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { prepareList, withKey } = helpers;
@@ -10,14 +10,14 @@ exports[`memory t-foreach does not leak stuff in global scope 1`] = `
  
  return function template(ctx, node, key = \\"\\") {
    ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList([3,2,1]);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList([3,2,1]);;
    for (let i1 = 0; i1 < l_block2; i1++) {
      ctx[\`item\`] = v_block2[i1];
      ctx[\`item_index\`] = i1;
-      let key1 = ctx['item_index'];
+      const key1 = ctx['item_index'];
      c_block2[i1] = withKey(text(ctx['item']), key1);
    }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
    return block1([], [b2]);
  }
 }"
@@ -1,7 +1,7 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP

 exports[`simple templates, mostly static can render a table row 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -14,7 +14,7 @@ exports[`simple templates, mostly static can render a table row 1`] = `
 `;

 exports[`simple templates, mostly static div with a class attribute 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -27,7 +27,7 @@ exports[`simple templates, mostly static div with a class attribute 1`] = `
 `;

 exports[`simple templates, mostly static div with a class attribute with a quote 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -40,7 +40,7 @@ exports[`simple templates, mostly static div with a class attribute with a quote
 `;

 exports[`simple templates, mostly static div with a span child node 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -53,7 +53,7 @@ exports[`simple templates, mostly static div with a span child node 1`] = `
 `;

 exports[`simple templates, mostly static div with an arbitrary attribute with a quote 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -66,7 +66,7 @@ exports[`simple templates, mostly static div with an arbitrary attribute with a
 `;

 exports[`simple templates, mostly static div with an empty class attribute 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -79,7 +79,7 @@ exports[`simple templates, mostly static div with an empty class attribute 1`] =
 `;

 exports[`simple templates, mostly static div with content 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -92,7 +92,7 @@ exports[`simple templates, mostly static div with content 1`] = `
 `;

 exports[`simple templates, mostly static dom node with t-esc 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -106,7 +106,7 @@ exports[`simple templates, mostly static dom node with t-esc 1`] = `
 `;

 exports[`simple templates, mostly static dom node with t-esc 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -120,7 +120,7 @@ exports[`simple templates, mostly static dom node with t-esc 2`] = `
 `;

 exports[`simple templates, mostly static dynamic text value 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -131,7 +131,7 @@ exports[`simple templates, mostly static dynamic text value 1`] = `
 `;

 exports[`simple templates, mostly static empty div 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -144,7 +144,7 @@ exports[`simple templates, mostly static empty div 1`] = `
 `;

 exports[`simple templates, mostly static empty string 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -155,7 +155,7 @@ exports[`simple templates, mostly static empty string 1`] = `
 `;

 exports[`simple templates, mostly static empty string in a template set 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -166,7 +166,7 @@ exports[`simple templates, mostly static empty string in a template set 1`] = `
 `;

 exports[`simple templates, mostly static inline template string in t-esc 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -177,7 +177,7 @@ exports[`simple templates, mostly static inline template string in t-esc 1`] = `
 `;

 exports[`simple templates, mostly static inline template string with content in t-esc 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue } = helpers;
@@ -192,7 +192,7 @@ exports[`simple templates, mostly static inline template string with content in
 `;

 exports[`simple templates, mostly static inline template string with variable in context 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -203,7 +203,7 @@ exports[`simple templates, mostly static inline template string with variable in
 `;

 exports[`simple templates, mostly static multiple root nodes 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -211,15 +211,15 @@ exports[`simple templates, mostly static multiple root nodes 1`] = `
  let block3 = createBlock(\`<span>hey</span>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = block2();
-    let b3 = block3();
+    const b2 = block2();
+    const b3 = block3();
    return multi([b2, b3]);
  }
 }"
 `;

 exports[`simple templates, mostly static simple string 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -230,7 +230,7 @@ exports[`simple templates, mostly static simple string 1`] = `
 `;

 exports[`simple templates, mostly static simple string in t tag 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -241,33 +241,33 @@ exports[`simple templates, mostly static simple string in t tag 1`] = `
 `;

 exports[`simple templates, mostly static static text and dynamic text (no t tag) 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = text(\`hello \`);
-    let b3 = text(ctx['text']);
+    const b2 = text(\`hello \`);
+    const b3 = text(ctx['text']);
    return multi([b2, b3]);
  }
 }"
 `;

 exports[`simple templates, mostly static static text and dynamic text 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = text(\`hello \`);
-    let b3 = text(ctx['text']);
+    const b2 = text(\`hello \`);
+    const b3 = text(ctx['text']);
    return multi([b2, b3]);
  }
 }"
 `;

 exports[`simple templates, mostly static t-esc in dom node 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -281,7 +281,7 @@ exports[`simple templates, mostly static t-esc in dom node 1`] = `
 `;

 exports[`simple templates, mostly static t-esc in dom node, variations 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -295,7 +295,7 @@ exports[`simple templates, mostly static t-esc in dom node, variations 1`] = `
 `;

 exports[`simple templates, mostly static t-esc in dom node, variations 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -309,7 +309,7 @@ exports[`simple templates, mostly static t-esc in dom node, variations 2`] = `
 `;

 exports[`simple templates, mostly static template with multiple t tag with multiple content 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -325,7 +325,7 @@ exports[`simple templates, mostly static template with multiple t tag with multi
 `;

 exports[`simple templates, mostly static template with t tag with multiple content 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -342,33 +342,33 @@ exports[`simple templates, mostly static template with t tag with multiple conte
 `;

 exports[`simple templates, mostly static two t-escs next to each other 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = text(ctx['text1']);
-    let b3 = text(ctx['text2']);
+    const b2 = text(ctx['text1']);
+    const b3 = text(ctx['text2']);
    return multi([b2, b3]);
  }
 }"
 `;

 exports[`simple templates, mostly static two t-escs next to each other 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = text(ctx['text1']);
-    let b3 = text(ctx['text2']);
+    const b2 = text(ctx['text1']);
+    const b3 = text(ctx['text2']);
    return multi([b2, b3]);
  }
 }"
 `;

 exports[`simple templates, mostly static two t-escs next to each other, in a div 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -1,7 +1,7 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP

 exports[`properly support svg add proper namespace to g tags 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -14,7 +14,7 @@ exports[`properly support svg add proper namespace to g tags 1`] = `
 `;

 exports[`properly support svg add proper namespace to svg 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -27,7 +27,7 @@ exports[`properly support svg add proper namespace to svg 1`] = `
 `;

 exports[`properly support svg namespace to g tags not added if already in svg namespace 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -40,7 +40,7 @@ exports[`properly support svg namespace to g tags not added if already in svg na
 `;

 exports[`properly support svg namespace to svg tags added even if already in svg namespace 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -52,28 +52,62 @@ exports[`properly support svg namespace to svg tags added even if already in svg
 }"
 `;

-exports[`properly support svg svg namespace added to sub-blocks (t-call) 1`] = `
-"function anonymous(bdom, helpers
+exports[`properly support svg svg creates new block if it is within html -- 2 1`] = `
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
-  let { getTemplate } = helpers;
-  const callTemplate_1 = getTemplate(\`path\`, \\"http://www.w3.org/2000/svg\\");
  
-  let block1 = createBlock(\`<svg block-ns=\\"http://www.w3.org/2000/svg\\"><block-child-0/></svg>\`);
+  let block1 = createBlock(\`<div><block-child-0/></div>\`);
+  let block2 = createBlock(\`<svg block-ns=\\"http://www.w3.org/2000/svg\\"><polygon fill=\\"#000000\\" points=\\"0 0 4 4 8 0\\" transform=\\"translate(5 7)\\"/><block-child-0/></svg>\`);
+  let block3 = createBlock(\`<path block-ns=\\"http://www.w3.org/2000/svg\\"/>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    let b3;
+    if (ctx['hasPath']) {
+      b3 = block3();
+    }
+    const b2 = block2([], [b3]);
    return block1([], [b2]);
  }
 }"
 `;

-exports[`properly support svg svg namespace added to sub-blocks (t-call) 2`] = `
-"function anonymous(bdom, helpers
+exports[`properly support svg svg creates new block if it is within html 1`] = `
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
-  let block1 = createBlock(\`<path/>\`);
+  let block1 = createBlock(\`<div><block-child-0/></div>\`);
+  let block2 = createBlock(\`<svg block-ns=\\"http://www.w3.org/2000/svg\\"><polygon fill=\\"#000000\\" points=\\"0 0 4 4 8 0\\" transform=\\"translate(5 7)\\"/></svg>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = block2();
+    return block1([], [b2]);
+  }
+}"
+`;
+
+exports[`properly support svg svg namespace added to sub templates if root tag is path 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  const callTemplate_1 = app.getTemplate(\`path\`);
+  
+  let block1 = createBlock(\`<svg block-ns=\\"http://www.w3.org/2000/svg\\"><block-child-0/></svg>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    return block1([], [b2]);
+  }
+}"
+`;
+
+exports[`properly support svg svg namespace added to sub templates if root tag is path 2`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block1 = createBlock(\`<path block-ns=\\"http://www.w3.org/2000/svg\\"/>\`);
  
  return function template(ctx, node, key = \\"\\") {
    return block1();
@@ -82,7 +116,7 @@ exports[`properly support svg svg namespace added to sub-blocks (t-call) 2`] = `
 `;

 exports[`properly support svg svg namespace added to sub-blocks 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -1,7 +1,7 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP

 exports[`debugging t-debug 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -21,7 +21,7 @@ exports[`debugging t-debug 1`] = `
 `;

 exports[`debugging t-debug on sub template 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -35,23 +35,22 @@ exports[`debugging t-debug on sub template 1`] = `
 `;

 exports[`debugging t-debug on sub template 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
-  let { getTemplate } = helpers;
-  const callTemplate_1 = getTemplate(\`sub\`);
+  const callTemplate_1 = app.getTemplate(\`sub\`);
  
  let block1 = createBlock(\`<div><block-child-0/></div>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    const b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`debugging t-log 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue } = helpers;
@@ -1,7 +1,7 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP

 exports[`t-esc div with falsy values 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -19,7 +19,7 @@ exports[`t-esc div with falsy values 1`] = `
 `;

 exports[`t-esc escaping 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -33,7 +33,7 @@ exports[`t-esc escaping 1`] = `
 `;

 exports[`t-esc escaping on a node 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -47,7 +47,7 @@ exports[`t-esc escaping on a node 1`] = `
 `;

 exports[`t-esc escaping on a node with a body 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { withDefault } = helpers;
@@ -62,7 +62,7 @@ exports[`t-esc escaping on a node with a body 1`] = `
 `;

 exports[`t-esc escaping on a node with a body, as a default 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { withDefault } = helpers;
@@ -77,27 +77,27 @@ exports[`t-esc escaping on a node with a body, as a default 1`] = `
 `;

 exports[`t-esc falsy values in text nodes 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = text(ctx['v1']);
-    let b3 = text(\`:\`);
-    let b4 = text(ctx['v2']);
-    let b5 = text(\`:\`);
-    let b6 = text(ctx['v3']);
-    let b7 = text(\`:\`);
-    let b8 = text(ctx['v4']);
-    let b9 = text(\`:\`);
-    let b10 = text(ctx['v5']);
+    const b2 = text(ctx['v1']);
+    const b3 = text(\`:\`);
+    const b4 = text(ctx['v2']);
+    const b5 = text(\`:\`);
+    const b6 = text(ctx['v3']);
+    const b7 = text(\`:\`);
+    const b8 = text(ctx['v4']);
+    const b9 = text(\`:\`);
+    const b10 = text(ctx['v5']);
    return multi([b2, b3, b4, b5, b6, b7, b8, b9, b10]);
  }
 }"
 `;

 exports[`t-esc literal 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -111,7 +111,7 @@ exports[`t-esc literal 1`] = `
 `;

 exports[`t-esc t-esc is escaped 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, LazyValue } = helpers;
@@ -134,7 +134,7 @@ exports[`t-esc t-esc is escaped 1`] = `
 `;

 exports[`t-esc t-esc work with spread operator 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -148,11 +148,11 @@ exports[`t-esc t-esc work with spread operator 1`] = `
 `;

 exports[`t-esc t-esc=0 is escaped 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
-  let { isBoundary, zero, getTemplate } = helpers;
-  const callTemplate_1 = getTemplate(\`sub\`);
+  let { isBoundary, zero } = helpers;
+  const callTemplate_1 = app.getTemplate(\`sub\`);
  
  let block1 = createBlock(\`<div><block-child-0/></div>\`);
  let block2 = createBlock(\`<p>escaped</p>\`);
@@ -160,16 +160,16 @@ exports[`t-esc t-esc=0 is escaped 1`] = `
  return function template(ctx, node, key = \\"\\") {
    ctx = Object.create(ctx);
    ctx[isBoundary] = 1;
-    let b2 = block2();
+    const b2 = block2();
    ctx[zero] = b2;
-    let b3 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    const b3 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
    return block1([], [b3]);
  }
 }"
 `;

 exports[`t-esc t-esc=0 is escaped 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { zero } = helpers;
@@ -184,7 +184,7 @@ exports[`t-esc t-esc=0 is escaped 2`] = `
 `;

 exports[`t-esc variable 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -1,7 +1,7 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP

 exports[`t-foreach does not pollute the rendering context 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { prepareList, withKey } = helpers;
@@ -10,20 +10,20 @@ exports[`t-foreach does not pollute the rendering context 1`] = `
  
  return function template(ctx, node, key = \\"\\") {
    ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList([1]);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList([1]);;
    for (let i1 = 0; i1 < l_block2; i1++) {
      ctx[\`item\`] = v_block2[i1];
-      let key1 = ctx['item'];
+      const key1 = ctx['item'];
      c_block2[i1] = withKey(text(ctx['item']), key1);
    }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-foreach iterate on items (on a element node) 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { prepareList, withKey } = helpers;
@@ -33,21 +33,21 @@ exports[`t-foreach iterate on items (on a element node) 1`] = `
  
  return function template(ctx, node, key = \\"\\") {
    ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList([1,2]);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList([1,2]);;
    for (let i1 = 0; i1 < l_block2; i1++) {
      ctx[\`item\`] = v_block2[i1];
-      let key1 = ctx['item'];
+      const key1 = ctx['item'];
      let txt1 = ctx['item'];
      c_block2[i1] = withKey(block3([txt1]), key1);
    }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-foreach iterate on items 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { prepareList, withKey } = helpers;
@@ -56,29 +56,29 @@ exports[`t-foreach iterate on items 1`] = `
  
  return function template(ctx, node, key = \\"\\") {
    ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList([3,2,1]);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList([3,2,1]);;
    for (let i1 = 0; i1 < l_block2; i1++) {
      ctx[\`item\`] = v_block2[i1];
      ctx[\`item_index\`] = i1;
      ctx[\`item_value\`] = k_block2[i1];
-      let key1 = ctx['item'];
-      let b4 = text(\` [\`);
-      let b5 = text(ctx['item_index']);
-      let b6 = text(\`: \`);
-      let b7 = text(ctx['item']);
-      let b8 = text(\` \`);
-      let b9 = text(ctx['item_value']);
-      let b10 = text(\`] \`);
+      const key1 = ctx['item'];
+      const b4 = text(\` [\`);
+      const b5 = text(ctx['item_index']);
+      const b6 = text(\`: \`);
+      const b7 = text(ctx['item']);
+      const b8 = text(\` \`);
+      const b9 = text(ctx['item_value']);
+      const b10 = text(\`] \`);
      c_block2[i1] = withKey(multi([b4, b5, b6, b7, b8, b9, b10]), key1);
    }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-foreach iterate, dict param 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { prepareList, withKey } = helpers;
@@ -87,29 +87,29 @@ exports[`t-foreach iterate, dict param 1`] = `
  
  return function template(ctx, node, key = \\"\\") {
    ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['value']);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['value']);;
    for (let i1 = 0; i1 < l_block2; i1++) {
      ctx[\`item\`] = v_block2[i1];
      ctx[\`item_index\`] = i1;
      ctx[\`item_value\`] = k_block2[i1];
-      let key1 = ctx['item_index'];
-      let b4 = text(\` [\`);
-      let b5 = text(ctx['item_index']);
-      let b6 = text(\`: \`);
-      let b7 = text(ctx['item']);
-      let b8 = text(\` \`);
-      let b9 = text(ctx['item_value']);
-      let b10 = text(\`] \`);
+      const key1 = ctx['item_index'];
+      const b4 = text(\` [\`);
+      const b5 = text(ctx['item_index']);
+      const b6 = text(\`: \`);
+      const b7 = text(ctx['item']);
+      const b8 = text(\` \`);
+      const b9 = text(ctx['item_value']);
+      const b10 = text(\`] \`);
      c_block2[i1] = withKey(multi([b4, b5, b6, b7, b8, b9, b10]), key1);
    }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-foreach iterate, position 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { prepareList, withKey } = helpers;
@@ -118,13 +118,13 @@ exports[`t-foreach iterate, position 1`] = `
  
  return function template(ctx, node, key = \\"\\") {
    ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(Array(5));
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(Array(5));;
    for (let i1 = 0; i1 < l_block2; i1++) {
      ctx[\`elem\`] = v_block2[i1];
      ctx[\`elem_first\`] = i1 === 0;
      ctx[\`elem_last\`] = i1 === v_block2.length - 1;
      ctx[\`elem_index\`] = i1;
-      let key1 = ctx['elem'];
+      const key1 = ctx['elem'];
      let b4,b5,b6,b7,b8,b9;
      b4 = text(\` -\`);
      if (ctx['elem_first']) {
@@ -138,14 +138,14 @@ exports[`t-foreach iterate, position 1`] = `
      b9 = text(\`) \`);
      c_block2[i1] = withKey(multi([b4, b5, b6, b7, b8, b9]), key1);
    }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-foreach simple iteration (in a node) 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { prepareList, withKey } = helpers;
@@ -154,30 +154,30 @@ exports[`t-foreach simple iteration (in a node) 1`] = `
  
  return function template(ctx, node, key = \\"\\") {
    ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList([3,2,1]);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList([3,2,1]);;
    for (let i1 = 0; i1 < l_block2; i1++) {
      ctx[\`item\`] = v_block2[i1];
-      let key1 = ctx['item'];
+      const key1 = ctx['item'];
      c_block2[i1] = withKey(text(ctx['item']), key1);
    }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-foreach simple iteration 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { prepareList, withKey } = helpers;
  
  return function template(ctx, node, key = \\"\\") {
    ctx = Object.create(ctx);
-    const [k_block1, v_block1, l_block1, c_block1] = prepareList([3,2,1]);
+    const [k_block1, v_block1, l_block1, c_block1] = prepareList([3,2,1]);;
    for (let i1 = 0; i1 < l_block1; i1++) {
      ctx[\`item\`] = v_block1[i1];
-      let key1 = ctx['item'];
+      const key1 = ctx['item'];
      c_block1[i1] = withKey(text(ctx['item']), key1);
    }
    return list(c_block1);
@@ -186,7 +186,7 @@ exports[`t-foreach simple iteration 1`] = `
 `;

 exports[`t-foreach simple iteration with two nodes inside 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { prepareList, withKey } = helpers;
@@ -196,14 +196,14 @@ exports[`t-foreach simple iteration with two nodes inside 1`] = `
  
  return function template(ctx, node, key = \\"\\") {
    ctx = Object.create(ctx);
-    const [k_block1, v_block1, l_block1, c_block1] = prepareList([3,2,1]);
+    const [k_block1, v_block1, l_block1, c_block1] = prepareList([3,2,1]);;
    for (let i1 = 0; i1 < l_block1; i1++) {
      ctx[\`item\`] = v_block1[i1];
-      let key1 = ctx['item'];
+      const key1 = ctx['item'];
      let txt1 = ctx['item'];
-      let b3 = block3([txt1]);
+      const b3 = block3([txt1]);
      let txt2 = ctx['item'];
-      let b4 = block4([txt2]);
+      const b4 = block4([txt2]);
      c_block1[i1] = withKey(multi([b3, b4]), key1);
    }
    return list(c_block1);
@@ -212,11 +212,11 @@ exports[`t-foreach simple iteration with two nodes inside 1`] = `
 `;

 exports[`t-foreach t-call with body in t-foreach in t-foreach 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
-  let { prepareList, isBoundary, withDefault, setContextValue, getTemplate, withKey } = helpers;
-  const callTemplate_1 = getTemplate(\`sub\`);
+  let { prepareList, isBoundary, withDefault, setContextValue, withKey } = helpers;
+  const callTemplate_1 = app.getTemplate(\`sub\`);
  
  let block1 = createBlock(\`<div><block-child-0/><span>[<block-text-0/>][<block-text-1/>][<block-text-2/>]</span></div>\`);
  let block6 = createBlock(\`<span><block-text-0/></span>\`);
@@ -225,23 +225,23 @@ exports[`t-foreach t-call with body in t-foreach in t-foreach 1`] = `
    ctx = Object.create(ctx);
    ctx[isBoundary] = 1
    ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['numbers']);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['numbers']);;
    for (let i1 = 0; i1 < l_block2; i1++) {
      ctx[\`a\`] = v_block2[i1];
      ctx[\`a_first\`] = i1 === 0;
      ctx[\`a_last\`] = i1 === v_block2.length - 1;
      ctx[\`a_index\`] = i1;
      ctx[\`a_value\`] = k_block2[i1];
-      let key1 = ctx['a'];
+      const key1 = ctx['a'];
      ctx = Object.create(ctx);
-      const [k_block4, v_block4, l_block4, c_block4] = prepareList(ctx['letters']);
+      const [k_block4, v_block4, l_block4, c_block4] = prepareList(ctx['letters']);;
      for (let i2 = 0; i2 < l_block4; i2++) {
        ctx[\`b\`] = v_block4[i2];
        ctx[\`b_first\`] = i2 === 0;
        ctx[\`b_last\`] = i2 === v_block4.length - 1;
        ctx[\`b_index\`] = i2;
        ctx[\`b_value\`] = k_block4[i2];
-        let key2 = ctx['b'];
+        const key2 = ctx['b'];
        ctx = Object.create(ctx);
        ctx[isBoundary] = 1;
        setContextValue(ctx, \\"c\\", 'x'+'_'+ctx['a']+'_'+ctx['b']);
@@ -249,13 +249,13 @@ exports[`t-foreach t-call with body in t-foreach in t-foreach 1`] = `
        ctx = ctx.__proto__;
      }
      ctx = ctx.__proto__;
-      let b4 = list(c_block4);
+      const b4 = list(c_block4);
      let txt1 = ctx['c'];
-      let b6 = block6([txt1]);
+      const b6 = block6([txt1]);
      c_block2[i1] = withKey(multi([b4, b6]), key1);
    }
    ctx = ctx.__proto__;
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
    let txt2 = ctx['a'];
    let txt3 = ctx['b'];
    let txt4 = ctx['c'];
@@ -265,62 +265,62 @@ exports[`t-foreach t-call with body in t-foreach in t-foreach 1`] = `
 `;

 exports[`t-foreach t-call with body in t-foreach in t-foreach 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = text(\` [\`);
-    let b3 = text(ctx['a']);
-    let b4 = text(\`] [\`);
-    let b5 = text(ctx['b']);
-    let b6 = text(\`] [\`);
-    let b7 = text(ctx['c']);
-    let b8 = text(\`] \`);
+    const b2 = text(\` [\`);
+    const b3 = text(ctx['a']);
+    const b4 = text(\`] [\`);
+    const b5 = text(ctx['b']);
+    const b6 = text(\`] [\`);
+    const b7 = text(ctx['c']);
+    const b8 = text(\`] \`);
    return multi([b2, b3, b4, b5, b6, b7, b8]);
  }
 }"
 `;

 exports[`t-foreach t-call without body in t-foreach in t-foreach 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
-  let { prepareList, getTemplate, withKey } = helpers;
-  const callTemplate_1 = getTemplate(\`sub\`);
+  let { prepareList, withKey } = helpers;
+  const callTemplate_1 = app.getTemplate(\`sub\`);
  
  let block1 = createBlock(\`<div><block-child-0/><span>[<block-text-0/>][<block-text-1/>][<block-text-2/>]</span></div>\`);
  let block6 = createBlock(\`<span><block-text-0/></span>\`);
  
  return function template(ctx, node, key = \\"\\") {
    ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['numbers']);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['numbers']);;
    for (let i1 = 0; i1 < l_block2; i1++) {
      ctx[\`a\`] = v_block2[i1];
      ctx[\`a_first\`] = i1 === 0;
      ctx[\`a_last\`] = i1 === v_block2.length - 1;
      ctx[\`a_index\`] = i1;
      ctx[\`a_value\`] = k_block2[i1];
-      let key1 = ctx['a'];
+      const key1 = ctx['a'];
      ctx = Object.create(ctx);
-      const [k_block4, v_block4, l_block4, c_block4] = prepareList(ctx['letters']);
+      const [k_block4, v_block4, l_block4, c_block4] = prepareList(ctx['letters']);;
      for (let i2 = 0; i2 < l_block4; i2++) {
        ctx[\`b\`] = v_block4[i2];
        ctx[\`b_first\`] = i2 === 0;
        ctx[\`b_last\`] = i2 === v_block4.length - 1;
        ctx[\`b_index\`] = i2;
        ctx[\`b_value\`] = k_block4[i2];
-        let key2 = ctx['b'];
+        const key2 = ctx['b'];
        c_block4[i2] = withKey(callTemplate_1.call(this, ctx, node, key + \`__1__\${key1}__\${key2}\`), key2);
      }
      ctx = ctx.__proto__;
-      let b4 = list(c_block4);
+      const b4 = list(c_block4);
      let txt1 = ctx['c'];
-      let b6 = block6([txt1]);
+      const b6 = block6([txt1]);
      c_block2[i1] = withKey(multi([b4, b6]), key1);
    }
    ctx = ctx.__proto__;
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
    let txt2 = ctx['a'];
    let txt3 = ctx['b'];
    let txt4 = ctx['c'];
@@ -330,7 +330,7 @@ exports[`t-foreach t-call without body in t-foreach in t-foreach 1`] = `
 `;

 exports[`t-foreach t-call without body in t-foreach in t-foreach 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue } = helpers;
@@ -339,20 +339,20 @@ exports[`t-foreach t-call without body in t-foreach in t-foreach 2`] = `
    ctx = Object.create(ctx);
    ctx[isBoundary] = 1
    setContextValue(ctx, \\"c\\", 'x'+'_'+ctx['a']+'_'+ctx['b']);
-    let b2 = text(\` [\`);
-    let b3 = text(ctx['a']);
-    let b4 = text(\`] [\`);
-    let b5 = text(ctx['b']);
-    let b6 = text(\`] [\`);
-    let b7 = text(ctx['c']);
-    let b8 = text(\`] \`);
+    const b2 = text(\` [\`);
+    const b3 = text(ctx['a']);
+    const b4 = text(\`] [\`);
+    const b5 = text(ctx['b']);
+    const b6 = text(\`] [\`);
+    const b7 = text(ctx['c']);
+    const b8 = text(\`] \`);
    return multi([b2, b3, b4, b5, b6, b7, b8]);
  }
 }"
 `;

 exports[`t-foreach t-foreach in t-foreach 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { prepareList, withKey } = helpers;
@@ -361,32 +361,32 @@ exports[`t-foreach t-foreach in t-foreach 1`] = `
  
  return function template(ctx, node, key = \\"\\") {
    ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['numbers']);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['numbers']);;
    for (let i1 = 0; i1 < l_block2; i1++) {
      ctx[\`number\`] = v_block2[i1];
-      let key1 = ctx['number'];
+      const key1 = ctx['number'];
      ctx = Object.create(ctx);
-      const [k_block3, v_block3, l_block3, c_block3] = prepareList(ctx['letters']);
+      const [k_block3, v_block3, l_block3, c_block3] = prepareList(ctx['letters']);;
      for (let i2 = 0; i2 < l_block3; i2++) {
        ctx[\`letter\`] = v_block3[i2];
-        let key2 = ctx['letter'];
-        let b5 = text(\` [\`);
-        let b6 = text(ctx['number']);
-        let b7 = text(ctx['letter']);
-        let b8 = text(\`] \`);
+        const key2 = ctx['letter'];
+        const b5 = text(\` [\`);
+        const b6 = text(ctx['number']);
+        const b7 = text(ctx['letter']);
+        const b8 = text(\`] \`);
        c_block3[i2] = withKey(multi([b5, b6, b7, b8]), key2);
      }
      ctx = ctx.__proto__;
      c_block2[i1] = withKey(list(c_block3), key1);
    }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-foreach t-foreach with t-if inside (no external node) 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { prepareList, withKey } = helpers;
@@ -395,10 +395,10 @@ exports[`t-foreach t-foreach with t-if inside (no external node) 1`] = `
  
  return function template(ctx, node, key = \\"\\") {
    ctx = Object.create(ctx);
-    const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['elems']);
+    const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['elems']);;
    for (let i1 = 0; i1 < l_block1; i1++) {
      ctx[\`elem\`] = v_block1[i1];
-      let key1 = ctx['elem'].id;
+      const key1 = ctx['elem'].id;
      let b3;
      if (ctx['elem'].id<3) {
        let txt1 = ctx['elem'].text;
@@ -412,7 +412,7 @@ exports[`t-foreach t-foreach with t-if inside (no external node) 1`] = `
 `;

 exports[`t-foreach t-foreach with t-if inside 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { prepareList, withKey } = helpers;
@@ -422,10 +422,10 @@ exports[`t-foreach t-foreach with t-if inside 1`] = `
  
  return function template(ctx, node, key = \\"\\") {
    ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['elems']);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['elems']);;
    for (let i1 = 0; i1 < l_block2; i1++) {
      ctx[\`elem\`] = v_block2[i1];
-      let key1 = ctx['elem'].id;
+      const key1 = ctx['elem'].id;
      let b4;
      if (ctx['elem'].id<3) {
        let txt1 = ctx['elem'].text;
@@ -433,14 +433,14 @@ exports[`t-foreach t-foreach with t-if inside 1`] = `
      }
      c_block2[i1] = withKey(multi([b4]), key1);
    }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-foreach t-key on t-foreach 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { prepareList, withKey } = helpers;
@@ -450,20 +450,20 @@ exports[`t-foreach t-key on t-foreach 1`] = `
  
  return function template(ctx, node, key = \\"\\") {
    ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['things']);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['things']);;
    for (let i1 = 0; i1 < l_block2; i1++) {
      ctx[\`thing\`] = v_block2[i1];
-      let key1 = ctx['thing'];
+      const key1 = ctx['thing'];
      c_block2[i1] = withKey(block3(), key1);
    }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-foreach throws error if invalid loop expression 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { prepareList, withKey } = helpers;
@@ -473,22 +473,22 @@ exports[`t-foreach throws error if invalid loop expression 1`] = `
  
  return function template(ctx, node, key = \\"\\") {
    ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['abc']);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['abc']);;
    for (let i1 = 0; i1 < l_block2; i1++) {
      ctx[\`item\`] = v_block2[i1];
      ctx[\`item_index\`] = i1;
-      let key1 = ctx['item'];
+      const key1 = ctx['item'];
      const tKey_1 = ctx['item_index'];
      c_block2[i1] = withKey(block3(), tKey_1 + key1);
    }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-foreach with t-memo 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { prepareList, withKey } = helpers;
@@ -500,12 +500,12 @@ exports[`t-foreach with t-memo 1`] = `
    let cache = ctx.cache || {};
    let nextCache = ctx.cache = {};
    ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['items']);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['items']);;
    for (let i1 = 0; i1 < l_block2; i1++) {
      ctx[\`item\`] = v_block2[i1];
-      let key1 = ctx['item'].id;
-      let memo1 = [ctx['item'].x]
-      let vnode1 = cache[key1];
+      const key1 = ctx['item'].id;
+      const memo1 = [ctx['item'].x];
+      const vnode1 = cache[key1];;
      if (vnode1) {
        if (shallowEqual(vnode1.memo, memo1)) {
          c_block2[i1] = vnode1;
@@ -518,7 +518,7 @@ exports[`t-foreach with t-memo 1`] = `
      c_block2[i1] = withKey(block3([txt1, txt2]), key1);
      nextCache[key1] = Object.assign(c_block2[i1], {memo: memo1});
    }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
    return block1([], [b2]);
  }
 }"
@@ -1,7 +1,7 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP

 exports[`t-if a t-if next to a div 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -19,7 +19,7 @@ exports[`t-if a t-if next to a div 1`] = `
 `;

 exports[`t-if a t-if with two inner nodes 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -29,8 +29,8 @@ exports[`t-if a t-if with two inner nodes 1`] = `
  return function template(ctx, node, key = \\"\\") {
    let b2;
    if (ctx['condition']) {
-      let b3 = block3();
-      let b4 = block4();
+      const b3 = block3();
+      const b4 = block4();
      b2 = multi([b3, b4]);
    }
    return multi([b2]);
@@ -39,7 +39,7 @@ exports[`t-if a t-if with two inner nodes 1`] = `
 `;

 exports[`t-if boolean value condition elif (no outside node) 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -60,7 +60,7 @@ exports[`t-if boolean value condition elif (no outside node) 1`] = `
 `;

 exports[`t-if boolean value condition elif 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -83,7 +83,7 @@ exports[`t-if boolean value condition elif 1`] = `
 `;

 exports[`t-if boolean value condition else 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -102,7 +102,7 @@ exports[`t-if boolean value condition else 1`] = `
 `;

 exports[`t-if boolean value condition false else 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -121,7 +121,7 @@ exports[`t-if boolean value condition false else 1`] = `
 `;

 exports[`t-if boolean value condition missing 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -138,7 +138,7 @@ exports[`t-if boolean value condition missing 1`] = `
 `;

 exports[`t-if can use some boolean operators in expressions 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -176,7 +176,7 @@ exports[`t-if can use some boolean operators in expressions 1`] = `
 `;

 exports[`t-if div containing a t-if with two inner nodes 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -187,8 +187,8 @@ exports[`t-if div containing a t-if with two inner nodes 1`] = `
  return function template(ctx, node, key = \\"\\") {
    let b2;
    if (ctx['condition']) {
-      let b3 = block3();
-      let b4 = block4();
+      const b3 = block3();
+      const b4 = block4();
      b2 = multi([b3, b4]);
    }
    return block1([], [b2]);
@@ -197,7 +197,7 @@ exports[`t-if div containing a t-if with two inner nodes 1`] = `
 `;

 exports[`t-if dynamic content after t-if with two children nodes 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -208,8 +208,8 @@ exports[`t-if dynamic content after t-if with two children nodes 1`] = `
  return function template(ctx, node, key = \\"\\") {
    let b2;
    if (ctx['condition']) {
-      let b3 = block3();
-      let b4 = block4();
+      const b3 = block3();
+      const b4 = block4();
      b2 = multi([b3, b4]);
    }
    let txt1 = ctx['text'];
@@ -219,7 +219,7 @@ exports[`t-if dynamic content after t-if with two children nodes 1`] = `
 `;

 exports[`t-if just a t-if 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -234,7 +234,7 @@ exports[`t-if just a t-if 1`] = `
 `;

 exports[`t-if simple t-if/t-else 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -251,7 +251,7 @@ exports[`t-if simple t-if/t-else 1`] = `
 `;

 exports[`t-if simple t-if/t-else in a div 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -270,7 +270,7 @@ exports[`t-if simple t-if/t-else in a div 1`] = `
 `;

 exports[`t-if t-esc with t-elif 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -289,7 +289,7 @@ exports[`t-if t-esc with t-elif 1`] = `
 `;

 exports[`t-if t-esc with t-if 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -306,7 +306,7 @@ exports[`t-if t-esc with t-if 1`] = `
 `;

 exports[`t-if t-if and t-else with two nodes 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -318,8 +318,8 @@ exports[`t-if t-if and t-else with two nodes 1`] = `
    if (ctx['condition']) {
      b2 = text(\`1\`);
    } else {
-      let b4 = block4();
-      let b5 = block5();
+      const b4 = block4();
+      const b5 = block5();
      b3 = multi([b4, b5]);
    }
    return multi([b2, b3]);
@@ -328,7 +328,7 @@ exports[`t-if t-if and t-else with two nodes 1`] = `
 `;

 exports[`t-if t-if in a div 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -345,7 +345,7 @@ exports[`t-if t-if in a div 1`] = `
 `;

 exports[`t-if t-if in a t-if 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -367,7 +367,7 @@ exports[`t-if t-if in a t-if 1`] = `
 `;

 exports[`t-if t-if with empty content 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -383,7 +383,7 @@ exports[`t-if t-if with empty content 1`] = `
 `;

 exports[`t-if t-if/t-else with more content 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -402,7 +402,7 @@ exports[`t-if t-if/t-else with more content 1`] = `
 `;

 exports[`t-if t-set, then t-if 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue } = helpers;
@@ -423,7 +423,7 @@ exports[`t-if t-set, then t-if 1`] = `
 `;

 exports[`t-if t-set, then t-if, part 2 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue } = helpers;
@@ -446,7 +446,7 @@ exports[`t-if t-set, then t-if, part 2 1`] = `
 `;

 exports[`t-if t-set, then t-if, part 3 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue } = helpers;
@@ -472,7 +472,7 @@ exports[`t-if t-set, then t-if, part 3 1`] = `
 `;

 exports[`t-if two consecutive t-if 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -490,7 +490,7 @@ exports[`t-if two consecutive t-if 1`] = `
 `;

 exports[`t-if two consecutive t-if in a div 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -510,7 +510,7 @@ exports[`t-if two consecutive t-if in a div 1`] = `
 `;

 exports[`t-if two t-ifs next to each other 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -526,8 +526,8 @@ exports[`t-if two t-ifs next to each other 1`] = `
      b2 = block2([txt1]);
    }
    if (ctx['condition']) {
-      let b4 = block4();
-      let b5 = block5();
+      const b4 = block4();
+      const b5 = block5();
      b3 = multi([b4, b5]);
    }
    return block1([], [b2, b3]);
@@ -1,7 +1,7 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP

 exports[`t-key can use t-key directive on a node 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -16,7 +16,7 @@ exports[`t-key can use t-key directive on a node 1`] = `
 `;

 exports[`t-key can use t-key directive on a node 2 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -31,7 +31,7 @@ exports[`t-key can use t-key directive on a node 2 1`] = `
 `;

 exports[`t-key can use t-key directive on a node as a function 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -46,7 +46,7 @@ exports[`t-key can use t-key directive on a node as a function 1`] = `
 `;

 exports[`t-key t-key directive in a list 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { prepareList, withKey } = helpers;
@@ -56,21 +56,21 @@ exports[`t-key t-key directive in a list 1`] = `
  
  return function template(ctx, node, key = \\"\\") {
    ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['beers']);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['beers']);;
    for (let i1 = 0; i1 < l_block2; i1++) {
      ctx[\`beer\`] = v_block2[i1];
-      let key1 = ctx['beer'].id;
+      const key1 = ctx['beer'].id;
      let txt1 = ctx['beer'].name;
      c_block2[i1] = withKey(block3([txt1]), key1);
    }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-key t-key on sub dom node pushes a child block in its parent 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -91,7 +91,7 @@ exports[`t-key t-key on sub dom node pushes a child block in its parent 1`] = `
 `;

 exports[`t-key t-key on sub dom node pushes a child block in its parent 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -1,7 +1,7 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP

 exports[`t-out literal 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { safeOutput } = helpers;
@@ -9,14 +9,14 @@ exports[`t-out literal 1`] = `
  let block1 = createBlock(\`<span><block-child-0/></span>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput('ok');
+    const b2 = safeOutput('ok');
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-out literal, no outside html element 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { safeOutput } = helpers;
@@ -28,11 +28,11 @@ exports[`t-out literal, no outside html element 1`] = `
 `;

 exports[`t-out multiple calls to t-out 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
-  let { isBoundary, zero, getTemplate } = helpers;
-  const callTemplate_1 = getTemplate(\`sub\`);
+  let { isBoundary, zero } = helpers;
+  const callTemplate_1 = app.getTemplate(\`sub\`);
  
  let block1 = createBlock(\`<div><block-child-0/></div>\`);
  let block2 = createBlock(\`<span>coucou</span>\`);
@@ -40,16 +40,16 @@ exports[`t-out multiple calls to t-out 1`] = `
  return function template(ctx, node, key = \\"\\") {
    ctx = Object.create(ctx);
    ctx[isBoundary] = 1;
-    let b2 = block2();
+    const b2 = block2();
    ctx[zero] = b2;
-    let b3 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    const b3 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
    return block1([], [b3]);
  }
 }"
 `;

 exports[`t-out multiple calls to t-out 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { zero } = helpers;
@@ -57,15 +57,15 @@ exports[`t-out multiple calls to t-out 2`] = `
  let block1 = createBlock(\`<div><block-child-0/><div>Greeter</div><block-child-1/></div>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = ctx[zero];
-    let b3 = ctx[zero];
+    const b2 = ctx[zero];
+    const b3 = ctx[zero];
    return block1([], [b2, b3]);
  }
 }"
 `;

 exports[`t-out not escaping 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { safeOutput } = helpers;
@@ -73,18 +73,33 @@ exports[`t-out not escaping 1`] = `
  let block1 = createBlock(\`<div><block-child-0/></div>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['var']);
+    const b2 = safeOutput(ctx['var']);
+    return block1([], [b2]);
+  }
+}"
+`;
+
+exports[`t-out number literal 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { safeOutput } = helpers;
+  
+  let block1 = createBlock(\`<span><block-child-0/></span>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = safeOutput(1);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-out t-out 0 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
-  let { isBoundary, zero, getTemplate } = helpers;
-  const callTemplate_1 = getTemplate(\`_basic-callee\`);
+  let { isBoundary, zero } = helpers;
+  const callTemplate_1 = app.getTemplate(\`_basic-callee\`);
  
  let block1 = createBlock(\`<div><block-child-0/></div>\`);
  let block2 = createBlock(\`<div>zero</div>\`);
@@ -92,16 +107,16 @@ exports[`t-out t-out 0 1`] = `
  return function template(ctx, node, key = \\"\\") {
    ctx = Object.create(ctx);
    ctx[isBoundary] = 1;
-    let b2 = block2();
+    const b2 = block2();
    ctx[zero] = b2;
-    let b3 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    const b3 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
    return block1([], [b3]);
  }
 }"
 `;

 exports[`t-out t-out 0 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { zero } = helpers;
@@ -109,14 +124,14 @@ exports[`t-out t-out 0 2`] = `
  let block1 = createBlock(\`<div><block-child-0/></div>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = ctx[zero];
+    const b2 = ctx[zero];
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-out t-out and another sibling node 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { safeOutput } = helpers;
@@ -124,14 +139,14 @@ exports[`t-out t-out and another sibling node 1`] = `
  let block1 = createBlock(\`<span><span>hello</span><block-child-0/></span>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['var']);
+    const b2 = safeOutput(ctx['var']);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-out t-out bdom 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, LazyValue, safeOutput } = helpers;
@@ -147,14 +162,14 @@ exports[`t-out t-out bdom 1`] = `
    ctx = Object.create(ctx);
    ctx[isBoundary] = 1
    ctx[\`var\`] = new LazyValue(value1, ctx, node);
-    let b3 = safeOutput(ctx['var']);
+    const b3 = safeOutput(ctx['var']);
    return block1([], [b3]);
  }
 }"
 `;

 exports[`t-out t-out block 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { safeOutput } = helpers;
@@ -162,14 +177,14 @@ exports[`t-out t-out block 1`] = `
  let block1 = createBlock(\`<span><block-child-0/></span>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['bdom']);
+    const b2 = safeOutput(ctx['bdom']);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-out t-out escaped 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { safeOutput } = helpers;
@@ -177,14 +192,14 @@ exports[`t-out t-out escaped 1`] = `
  let block1 = createBlock(\`<span><block-child-0/></span>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['var']);
+    const b2 = safeOutput(ctx['var']);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-out t-out markedup 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { safeOutput } = helpers;
@@ -192,14 +207,14 @@ exports[`t-out t-out markedup 1`] = `
  let block1 = createBlock(\`<span><block-child-0/></span>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['var']);
+    const b2 = safeOutput(ctx['var']);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-out t-out on a node with a body, as a default 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { safeOutput, withDefault } = helpers;
@@ -207,15 +222,15 @@ exports[`t-out t-out on a node with a body, as a default 1`] = `
  let block1 = createBlock(\`<span><block-child-0/></span>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b3 = text(\`nope\`);
-    let b2 = withDefault(safeOutput(ctx['var']), b3);
+    const b3 = text(\`nope\`);
+    const b2 = withDefault(safeOutput(ctx['var']), b3);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-out t-out on a node with a dom node in body, as a default 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { safeOutput, withDefault } = helpers;
@@ -224,15 +239,15 @@ exports[`t-out t-out on a node with a dom node in body, as a default 1`] = `
  let block3 = createBlock(\`<div>nope</div>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b3 = block3();
-    let b2 = withDefault(safeOutput(ctx['var']), b3);
+    const b3 = block3();
+    const b2 = withDefault(safeOutput(ctx['var']), b3);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-out t-out switch escaped 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { safeOutput } = helpers;
@@ -240,14 +255,14 @@ exports[`t-out t-out switch escaped 1`] = `
  let block1 = createBlock(\`<span><block-child-0/></span>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['var']);
+    const b2 = safeOutput(ctx['var']);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-out t-out switch escaped on markup 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { safeOutput } = helpers;
@@ -255,14 +270,14 @@ exports[`t-out t-out switch escaped on markup 1`] = `
  let block1 = createBlock(\`<span><block-child-0/></span>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['var']);
+    const b2 = safeOutput(ctx['var']);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-out t-out switch markup 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { safeOutput } = helpers;
@@ -270,14 +285,14 @@ exports[`t-out t-out switch markup 1`] = `
  let block1 = createBlock(\`<span><block-child-0/></span>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['var']);
+    const b2 = safeOutput(ctx['var']);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-out t-out switch markup on bdom 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, LazyValue, safeOutput } = helpers;
@@ -297,10 +312,10 @@ exports[`t-out t-out switch markup on bdom 1`] = `
    let b3,b5;
    ctx[\`bdom\`] = new LazyValue(value1, ctx, node);
    if (ctx['hasBdom']) {
-      let b4 = safeOutput(ctx['bdom']);
+      const b4 = safeOutput(ctx['bdom']);
      b3 = block3([], [b4]);
    } else {
-      let b6 = safeOutput(ctx['var']);
+      const b6 = safeOutput(ctx['var']);
      b5 = block5([], [b6]);
    }
    return block1([], [b3, b5]);
@@ -309,7 +324,7 @@ exports[`t-out t-out switch markup on bdom 1`] = `
 `;

 exports[`t-out t-out switch markup on escaped 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { safeOutput } = helpers;
@@ -317,14 +332,14 @@ exports[`t-out t-out switch markup on escaped 1`] = `
  let block1 = createBlock(\`<span><block-child-0/></span>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['var']);
+    const b2 = safeOutput(ctx['var']);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-out t-out with a <t/> in body 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { safeOutput } = helpers;
@@ -336,7 +351,7 @@ exports[`t-out t-out with a <t/> in body 1`] = `
 `;

 exports[`t-out t-out with arbitrary object 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { safeOutput } = helpers;
@@ -344,14 +359,14 @@ exports[`t-out t-out with arbitrary object 1`] = `
  let block1 = createBlock(\`<div><block-child-0/></div>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['var']);
+    const b2 = safeOutput(ctx['var']);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-out t-out with arbitrary object 2 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { safeOutput } = helpers;
@@ -359,14 +374,14 @@ exports[`t-out t-out with arbitrary object 2 1`] = `
  let block1 = createBlock(\`<div><block-child-0/></div>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['var']);
+    const b2 = safeOutput(ctx['var']);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-out t-out with comment 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { safeOutput } = helpers;
@@ -374,14 +389,14 @@ exports[`t-out t-out with comment 1`] = `
  let block1 = createBlock(\`<span><block-child-0/></span>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['var']);
+    const b2 = safeOutput(ctx['var']);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-out t-out with just a t-set t-value in body 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { safeOutput } = helpers;
@@ -393,7 +408,7 @@ exports[`t-out t-out with just a t-set t-value in body 1`] = `
 `;

 exports[`t-out variable 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { safeOutput } = helpers;
@@ -401,14 +416,44 @@ exports[`t-out variable 1`] = `
  let block1 = createBlock(\`<span><block-child-0/></span>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['var']);
+    const b2 = safeOutput(ctx['var']);
+    return block1([], [b2]);
+  }
+}"
+`;
+
+exports[`t-out with a String class 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { safeOutput } = helpers;
+  
+  let block1 = createBlock(\`<span><block-child-0/></span>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = safeOutput(ctx['var']);
+    return block1([], [b2]);
+  }
+}"
+`;
+
+exports[`t-out with an extended String class 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { safeOutput } = helpers;
+  
+  let block1 = createBlock(\`<span><block-child-0/></span>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = safeOutput(ctx['var']);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-raw is deprecated should warn 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { safeOutput } = helpers;
@@ -416,14 +461,14 @@ exports[`t-raw is deprecated should warn 1`] = `
  let block1 = createBlock(\`<div><block-child-0/></div>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['var']);
+    const b2 = safeOutput(ctx['var']);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-raw is deprecated t-out is actually called in t-raw's place 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { safeOutput } = helpers;
@@ -431,7 +476,7 @@ exports[`t-raw is deprecated t-out is actually called in t-raw's place 1`] = `
  let block1 = createBlock(\`<div><block-child-0/></div>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['var']);
+    const b2 = safeOutput(ctx['var']);
    return block1([], [b2]);
  }
 }"
@@ -1,7 +1,23 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP

 exports[`t-ref can get a dynamic ref on a node 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block1 = createBlock(\`<div><span block-ref=\\"0\\"/></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    const refs = ctx.__owl__.refs;
+    const v1 = ctx['id'];
+    let ref1 = (el) => refs[\`myspan\${v1}\`] = el;
+    return block1([ref1]);
+  }
+}"
+`;
+
+exports[`t-ref can get a dynamic ref on a node, alternate syntax 1`] = `
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -17,7 +33,7 @@ exports[`t-ref can get a dynamic ref on a node 1`] = `
 `;

 exports[`t-ref can get a ref on a node 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -32,23 +48,22 @@ exports[`t-ref can get a ref on a node 1`] = `
 `;

 exports[`t-ref ref in a t-call 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
-  let { getTemplate } = helpers;
-  const callTemplate_1 = getTemplate(\`sub\`);
+  const callTemplate_1 = app.getTemplate(\`sub\`);
  
  let block1 = createBlock(\`<div><block-child-0/></div>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    const b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-ref ref in a t-call 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -63,7 +78,7 @@ exports[`t-ref ref in a t-call 2`] = `
 `;

 exports[`t-ref ref in a t-if 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -83,7 +98,7 @@ exports[`t-ref ref in a t-if 1`] = `
 `;

 exports[`t-ref refs in a loop 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { prepareList, withKey } = helpers;
@@ -94,24 +109,24 @@ exports[`t-ref refs in a loop 1`] = `
  return function template(ctx, node, key = \\"\\") {
    const refs = ctx.__owl__.refs;
    ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['items']);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['items']);;
    for (let i1 = 0; i1 < l_block2; i1++) {
      ctx[\`item\`] = v_block2[i1];
-      let key1 = ctx['item'];
+      const key1 = ctx['item'];
      const tKey_1 = ctx['item'];
      const v1 = ctx['item'];
-      let ref1 = (el) => refs[\`\${v1}\`] = el;
+      let ref1 = (el) => refs[(v1)] = el;
      let txt1 = ctx['item'];
      c_block2[i1] = withKey(block3([ref1, txt1]), tKey_1 + key1);
    }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-ref two refs, one in a t-if 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -1,7 +1,7 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP

 exports[`t-set evaluate value expression 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue } = helpers;
@@ -19,7 +19,7 @@ exports[`t-set evaluate value expression 1`] = `
 `;

 exports[`t-set evaluate value expression, part 2 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue } = helpers;
@@ -37,7 +37,7 @@ exports[`t-set evaluate value expression, part 2 1`] = `
 `;

 exports[`t-set set from attribute literal (no outside div) 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue } = helpers;
@@ -52,7 +52,7 @@ exports[`t-set set from attribute literal (no outside div) 1`] = `
 `;

 exports[`t-set set from attribute literal 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue } = helpers;
@@ -70,7 +70,7 @@ exports[`t-set set from attribute literal 1`] = `
 `;

 exports[`t-set set from attribute lookup 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue } = helpers;
@@ -88,7 +88,7 @@ exports[`t-set set from attribute lookup 1`] = `
 `;

 exports[`t-set set from body literal (with t-if/t-else 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, LazyValue } = helpers;
@@ -113,7 +113,7 @@ exports[`t-set set from body literal (with t-if/t-else 1`] = `
 `;

 exports[`t-set set from body literal 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue } = helpers;
@@ -128,7 +128,7 @@ exports[`t-set set from body literal 1`] = `
 `;

 exports[`t-set set from body lookup 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, LazyValue } = helpers;
@@ -150,7 +150,7 @@ exports[`t-set set from body lookup 1`] = `
 `;

 exports[`t-set set from empty body 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue } = helpers;
@@ -168,7 +168,7 @@ exports[`t-set set from empty body 1`] = `
 `;

 exports[`t-set t-set and t-if 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue } = helpers;
@@ -189,7 +189,7 @@ exports[`t-set t-set and t-if 1`] = `
 `;

 exports[`t-set t-set body is evaluated immediately 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue, LazyValue, safeOutput } = helpers;
@@ -208,18 +208,18 @@ exports[`t-set t-set body is evaluated immediately 1`] = `
    setContextValue(ctx, \\"v1\\", 'before');
    ctx[\`v2\`] = new LazyValue(value1, ctx, node);
    setContextValue(ctx, \\"v1\\", 'after');
-    let b3 = safeOutput(ctx['v2']);
+    const b3 = safeOutput(ctx['v2']);
    return block1([], [b3]);
  }
 }"
 `;

 exports[`t-set t-set can't alter from within callee 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
-  let { isBoundary, withDefault, setContextValue, getTemplate } = helpers;
-  const callTemplate_1 = getTemplate(\`sub\`);
+  let { isBoundary, withDefault, setContextValue } = helpers;
+  const callTemplate_1 = app.getTemplate(\`sub\`);
  
  let block1 = createBlock(\`<div><p><block-text-0/></p><block-child-0/><p><block-text-1/></p></div>\`);
  
@@ -228,7 +228,7 @@ exports[`t-set t-set can't alter from within callee 1`] = `
    ctx[isBoundary] = 1
    setContextValue(ctx, \\"iter\\", 'source');
    let txt1 = ctx['iter'];
-    let b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    const b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
    let txt2 = ctx['iter'];
    return block1([txt1, txt2], [b2]);
  }
@@ -236,7 +236,7 @@ exports[`t-set t-set can't alter from within callee 1`] = `
 `;

 exports[`t-set t-set can't alter from within callee 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue } = helpers;
@@ -255,11 +255,11 @@ exports[`t-set t-set can't alter from within callee 2`] = `
 `;

 exports[`t-set t-set can't alter in t-call body 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
-  let { isBoundary, withDefault, setContextValue, getTemplate } = helpers;
-  const callTemplate_1 = getTemplate(\`sub\`);
+  let { isBoundary, withDefault, setContextValue } = helpers;
+  const callTemplate_1 = app.getTemplate(\`sub\`);
  
  let block1 = createBlock(\`<div><p><block-text-0/></p><block-child-0/><p><block-text-1/></p></div>\`);
  
@@ -271,7 +271,7 @@ exports[`t-set t-set can't alter in t-call body 1`] = `
    ctx = Object.create(ctx);
    ctx[isBoundary] = 1;
    setContextValue(ctx, \\"iter\\", 'inCall');
-    let b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    const b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
    ctx = ctx.__proto__;
    let txt2 = ctx['iter'];
    return block1([txt1, txt2], [b2]);
@@ -280,7 +280,7 @@ exports[`t-set t-set can't alter in t-call body 1`] = `
 `;

 exports[`t-set t-set can't alter in t-call body 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue } = helpers;
@@ -299,7 +299,7 @@ exports[`t-set t-set can't alter in t-call body 2`] = `
 `;

 exports[`t-set t-set does not modify render context existing key values 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue } = helpers;
@@ -317,7 +317,7 @@ exports[`t-set t-set does not modify render context existing key values 1`] = `
 `;

 exports[`t-set t-set evaluates an expression only once 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue } = helpers;
@@ -336,7 +336,7 @@ exports[`t-set t-set evaluates an expression only once 1`] = `
 `;

 exports[`t-set t-set outside modified in t-foreach 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue, prepareList, withKey } = helpers;
@@ -349,16 +349,16 @@ exports[`t-set t-set outside modified in t-foreach 1`] = `
    ctx[isBoundary] = 1
    setContextValue(ctx, \\"iter\\", 0);
    ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(['a','b']);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(['a','b']);;
    for (let i1 = 0; i1 < l_block2; i1++) {
      ctx[\`val\`] = v_block2[i1];
-      let key1 = ctx['val'];
+      const key1 = ctx['val'];
      let txt1 = ctx['iter'];
      c_block2[i1] = withKey(block3([txt1]), key1);
      setContextValue(ctx, \\"iter\\", ctx['iter']+1);
    }
    ctx = ctx.__proto__;
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
    let txt2 = ctx['iter'];
    return block1([txt2], [b2]);
  }
@@ -366,7 +366,7 @@ exports[`t-set t-set outside modified in t-foreach 1`] = `
 `;

 exports[`t-set t-set outside modified in t-foreach increment-after operator 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue, prepareList, withKey } = helpers;
@@ -379,16 +379,16 @@ exports[`t-set t-set outside modified in t-foreach increment-after operator 1`]
    ctx[isBoundary] = 1
    setContextValue(ctx, \\"iter\\", 0);
    ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(['a','b']);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(['a','b']);;
    for (let i1 = 0; i1 < l_block2; i1++) {
      ctx[\`val\`] = v_block2[i1];
-      let key1 = ctx['val'];
+      const key1 = ctx['val'];
      let txt1 = ctx['iter'];
      c_block2[i1] = withKey(block3([txt1]), key1);
      setContextValue(ctx, \\"iter\\", ctx['iter']++);
    }
    ctx = ctx.__proto__;
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
    let txt2 = ctx['iter'];
    return block1([txt2], [b2]);
  }
@@ -396,7 +396,7 @@ exports[`t-set t-set outside modified in t-foreach increment-after operator 1`]
 `;

 exports[`t-set t-set outside modified in t-foreach increment-before operator 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue, prepareList, withKey } = helpers;
@@ -409,16 +409,16 @@ exports[`t-set t-set outside modified in t-foreach increment-before operator 1`]
    ctx[isBoundary] = 1
    setContextValue(ctx, \\"iter\\", 0);
    ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(['a','b']);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(['a','b']);;
    for (let i1 = 0; i1 < l_block2; i1++) {
      ctx[\`val\`] = v_block2[i1];
-      let key1 = ctx['val'];
+      const key1 = ctx['val'];
      let txt1 = ctx['iter'];
      c_block2[i1] = withKey(block3([txt1]), key1);
      setContextValue(ctx, \\"iter\\", ++ctx['iter']);
    }
    ctx = ctx.__proto__;
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
    let txt2 = ctx['iter'];
    return block1([txt2], [b2]);
  }
@@ -426,7 +426,7 @@ exports[`t-set t-set outside modified in t-foreach increment-before operator 1`]
 `;

 exports[`t-set t-set should reuse variable if possible 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue, prepareList, withKey } = helpers;
@@ -439,23 +439,23 @@ exports[`t-set t-set should reuse variable if possible 1`] = `
    ctx[isBoundary] = 1
    setContextValue(ctx, \\"v\\", 1);
    ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['list']);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['list']);;
    for (let i1 = 0; i1 < l_block2; i1++) {
      ctx[\`elem\`] = v_block2[i1];
      ctx[\`elem_index\`] = i1;
-      let key1 = ctx['elem_index'];
+      const key1 = ctx['elem_index'];
      let txt1 = ctx['v'];
      setContextValue(ctx, \\"v\\", ctx['elem']);
      c_block2[i1] = withKey(block3([txt1]), key1);
    }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`t-set t-set with content and sub t-esc 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, LazyValue } = helpers;
@@ -463,8 +463,8 @@ exports[`t-set t-set with content and sub t-esc 1`] = `
  let block1 = createBlock(\`<div><block-text-0/></div>\`);
  
  function value1(ctx, node, key = \\"\\") {
-    let b3 = text(ctx['beep']);
-    let b4 = text(\` boop\`);
+    const b3 = text(ctx['beep']);
+    const b4 = text(\` boop\`);
    return multi([b3, b4]);
  }
  
@@ -479,7 +479,7 @@ exports[`t-set t-set with content and sub t-esc 1`] = `
 `;

 exports[`t-set t-set with t-value (falsy) and body 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue, LazyValue, safeOutput } = helpers;
@@ -500,14 +500,14 @@ exports[`t-set t-set with t-value (falsy) and body 1`] = `
    ctx[\`v2\`] = withDefault(ctx['v3'], new LazyValue(value1, ctx, node));
    setContextValue(ctx, \\"v1\\", 'after');
    setContextValue(ctx, \\"v3\\", true);
-    let b3 = safeOutput(ctx['v2']);
+    const b3 = safeOutput(ctx['v2']);
    return block1([], [b3]);
  }
 }"
 `;

 exports[`t-set t-set with t-value (truthy) and body 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue, LazyValue, safeOutput } = helpers;
@@ -528,14 +528,14 @@ exports[`t-set t-set with t-value (truthy) and body 1`] = `
    ctx[\`v2\`] = withDefault(ctx['v3'], new LazyValue(value1, ctx, node));
    setContextValue(ctx, \\"v1\\", 'after');
    setContextValue(ctx, \\"v3\\", false);
-    let b3 = safeOutput(ctx['v2']);
+    const b3 = safeOutput(ctx['v2']);
    return block1([], [b3]);
  }
 }"
 `;

 exports[`t-set t-set, t-if, and mix of expression/body lookup, 1 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue } = helpers;
@@ -557,7 +557,7 @@ exports[`t-set t-set, t-if, and mix of expression/body lookup, 1 1`] = `
 `;

 exports[`t-set t-set, t-if, and mix of expression/body lookup, 2 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue } = helpers;
@@ -579,7 +579,7 @@ exports[`t-set t-set, t-if, and mix of expression/body lookup, 2 1`] = `
 `;

 exports[`t-set t-set, t-if, and mix of expression/body lookup, 3 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue } = helpers;
@@ -600,7 +600,7 @@ exports[`t-set t-set, t-if, and mix of expression/body lookup, 3 1`] = `
 `;

 exports[`t-set value priority (with non text body 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, LazyValue } = helpers;
@@ -623,7 +623,7 @@ exports[`t-set value priority (with non text body 1`] = `
 `;

 exports[`t-set value priority 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  let { isBoundary, withDefault, setContextValue } = helpers;
@@ -1,91 +1,91 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP

 exports[`qweb t-tag can fallback if falsy tag 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
  let block1 = tag => createBlock(\`<\${tag || 'fallback'}/>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let tag1 = ctx['tag'];
+    const tag1 = ctx['tag'];
    return toggler(tag1, block1(tag1)());
  }
 }"
 `;

 exports[`qweb t-tag can update 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
  let block1 = tag => createBlock(\`<\${tag || 't'}/>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let tag1 = ctx['tag'];
+    const tag1 = ctx['tag'];
    return toggler(tag1, block1(tag1)());
  }
 }"
 `;

 exports[`qweb t-tag simple usecases 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
  let block1 = tag => createBlock(\`<\${tag || 't'}/>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let tag1 = 'div';
+    const tag1 = 'div';
    return toggler(tag1, block1(tag1)());
  }
 }"
 `;

 exports[`qweb t-tag simple usecases 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
  let block1 = tag => createBlock(\`<\${tag || 't'}>text</\${tag || 't'}>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let tag1 = ctx['tag'];
+    const tag1 = ctx['tag'];
    return toggler(tag1, block1(tag1)());
  }
 }"
 `;

 exports[`qweb t-tag with multiple attributes 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
  let block1 = tag => createBlock(\`<\${tag || 't'} class=\\"blueberry\\" taste=\\"raspberry\\">gooseberry</\${tag || 't'}>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let tag1 = ctx['tag'];
+    const tag1 = ctx['tag'];
    return toggler(tag1, block1(tag1)());
  }
 }"
 `;

 exports[`qweb t-tag with multiple child nodes 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
  let block1 = tag => createBlock(\`<\${tag || 't'}> pear <span>apple</span> strawberry </\${tag || 't'}>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let tag1 = ctx['tag'];
+    const tag1 = ctx['tag'];
    return toggler(tag1, block1(tag1)());
  }
 }"
 `;

 exports[`qweb t-tag with multiple t-tag in same template 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -93,16 +93,16 @@ exports[`qweb t-tag with multiple t-tag in same template 1`] = `
  let block2 = tag => createBlock(\`<\${tag || 't'}>baz</\${tag || 't'}>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let tag1 = ctx['outer'];
-    let tag2 = ctx['inner'];
-    let b2 = toggler(tag2, block2(tag2)());
+    const tag1 = ctx['outer'];
+    const tag2 = ctx['inner'];
+    const b2 = toggler(tag2, block2(tag2)());
    return toggler(tag1, block1(tag1)([], [b2]));
  }
 }"
 `;

 exports[`qweb t-tag with multiple t-tag in same template, part 2 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -110,10 +110,10 @@ exports[`qweb t-tag with multiple t-tag in same template, part 2 1`] = `
  let block3 = tag => createBlock(\`<\${tag || 't'}>baz</\${tag || 't'}>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let tag1 = ctx['brother'];
-    let b2 = toggler(tag1, block2(tag1)());
-    let tag2 = ctx['brother'];
-    let b3 = toggler(tag2, block3(tag2)());
+    const tag1 = ctx['brother'];
+    const b2 = toggler(tag1, block2(tag1)());
+    const tag2 = ctx['brother'];
+    const b3 = toggler(tag2, block3(tag2)());
    return multi([b2, b3]);
  }
 }"
@@ -1,7 +1,21 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP

+exports[`loading templates addTemplates does not modify its xml document in place 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block1 = createBlock(\`<div><block-text-0/></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let txt1 = ctx['value'];
+    return block1([txt1]);
+  }
+}"
+`;
+
 exports[`loading templates can initialize qweb with a string 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -14,7 +28,7 @@ exports[`loading templates can initialize qweb with a string 1`] = `
 `;

 exports[`loading templates can initialize qweb with an XMLDocument 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -27,23 +41,22 @@ exports[`loading templates can initialize qweb with an XMLDocument 1`] = `
 `;

 exports[`loading templates can load a few templates from a xml string 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
-  let { getTemplate } = helpers;
-  const callTemplate_1 = getTemplate(\`items\`);
+  const callTemplate_1 = app.getTemplate(\`items\`);
  
  let block1 = createBlock(\`<ul><block-child-0/></ul>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    const b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`loading templates can load a few templates from a xml string 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -51,31 +64,30 @@ exports[`loading templates can load a few templates from a xml string 2`] = `
  let block3 = createBlock(\`<li>foo</li>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = block2();
-    let b3 = block3();
+    const b2 = block2();
+    const b3 = block3();
    return multi([b2, b3]);
  }
 }"
 `;

 exports[`loading templates can load a few templates from an XMLDocument 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
-  let { getTemplate } = helpers;
-  const callTemplate_1 = getTemplate(\`items\`);
+  const callTemplate_1 = app.getTemplate(\`items\`);
  
  let block1 = createBlock(\`<ul><block-child-0/></ul>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    const b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
    return block1([], [b2]);
  }
 }"
 `;

 exports[`loading templates can load a few templates from an XMLDocument 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -83,8 +95,8 @@ exports[`loading templates can load a few templates from an XMLDocument 2`] = `
  let block3 = createBlock(\`<li>foo</li>\`);
  
  return function template(ctx, node, key = \\"\\") {
-    let b2 = block2();
-    let b3 = block3();
+    const b2 = block2();
+    const b3 = block3();
    return multi([b2, b3]);
  }
 }"
@@ -1,11 +1,11 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP

-exports[`translation support can set translatable attributes 1`] = `
-"function anonymous(bdom, helpers
+exports[`translation support can set and remove translatable attributes 1`] = `
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
-  let block1 = createBlock(\`<div tomato=\\"word\\" potato=\\"mot\\" title=\\"word\\">text</div>\`);
+  let block1 = createBlock(\`<div tomato=\\"word\\" potato=\\"mot\\" title=\\"mot\\" label=\\"word\\">text</div>\`);
  
  return function template(ctx, node, key = \\"\\") {
    return block1();
@@ -14,7 +14,7 @@ exports[`translation support can set translatable attributes 1`] = `
 `;

 exports[`translation support can translate node content 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -27,7 +27,7 @@ exports[`translation support can translate node content 1`] = `
 `;

 exports[`translation support does not translate node content if disabled 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -40,7 +40,7 @@ exports[`translation support does not translate node content if disabled 1`] = `
 `;

 exports[`translation support some attributes are translated 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -53,7 +53,7 @@ exports[`translation support some attributes are translated 1`] = `
 `;

 exports[`translation support translation is done on the trimmed text, with extra spaces readded after 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -1,7 +1,7 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP

 exports[`white space handling consecutives whitespaces are condensed into a single space 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -14,7 +14,7 @@ exports[`white space handling consecutives whitespaces are condensed into a sing
 `;

 exports[`white space handling nothing is done in pre tags 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -27,7 +27,7 @@ exports[`white space handling nothing is done in pre tags 1`] = `
 `;

 exports[`white space handling nothing is done in pre tags 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -42,7 +42,7 @@ exports[`white space handling nothing is done in pre tags 2`] = `
 `;

 exports[`white space handling nothing is done in pre tags 3`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -57,7 +57,7 @@ exports[`white space handling nothing is done in pre tags 3`] = `
 `;

 exports[`white space handling pre inside a div with a new line 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -70,7 +70,7 @@ exports[`white space handling pre inside a div with a new line 1`] = `
 `;

 exports[`white space handling white space only text nodes are condensed into a single space 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -83,7 +83,7 @@ exports[`white space handling white space only text nodes are condensed into a s
 `;

 exports[`white space handling whitespace only text nodes with newlines are removed 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
  
@@ -1,4 +1,4 @@
-import { mount, patch } from "../../src/blockdom";
+import { mount, patch } from "../../src/runtime/blockdom";
 import { makeTestFixture, renderToBdom, renderToString, snapshotEverything } from "../helpers";

 snapshotEverything();
@@ -131,6 +131,12 @@ describe("attributes", () => {
    expect(result).toBe(`<div foo="bar"></div>`);
  });

+  test("string interpolation, alternate syntax", () => {
+    const template = `<div t-attf-foo="b#{value}r"/>`;
+    const result = renderToString(template, { value: "a" });
+    expect(result).toBe(`<div foo="bar"></div>`);
+  });
+
  test("t-attf-class", () => {
    const template = `<div t-attf-class="hello"/>`;
    const result = renderToString(template);
@@ -0,0 +1,13 @@
+import { renderToString } from "../helpers";
+
+describe("blacklisted tags and attributes", () => {
+  test("template with block-text tag", () => {
+    const template = `<div><block-text-0/>hello</div>`;
+    expect(() => renderToString(template)).toThrow("Invalid tag name: 'block-text-0'");
+  });
+
+  test("template with block-handler tag", () => {
+    const template = `<div block-handler-0="click">hello</div>`;
+    expect(() => renderToString(template)).toThrow("Invalid attribute: 'block-handler-0'");
+  });
+});
--- a/Show More
+++ b/Show More