wip

# v2.0.7

 - [FIX] compiler: t-key and t-ref together

.eslintrc

@@ -0,0 +1,47 @@
+{
+    "env": {
+        "browser": true,
+        "node": true,
+        "es2022": true
+    },
+    "parser": "@typescript-eslint/parser",
+    "plugins": ["@typescript-eslint"],
+    "parserOptions": {
+        "sourceType": "module"
+    },
+    "root": true,
+    "rules": {
+        "no-restricted-globals": ["error", "event", "self"],
+        "no-const-assign": ["error"],
+        "no-debugger": ["error"],
+        "no-dupe-class-members": ["error"],
+        "no-dupe-keys": ["error"],
+        "no-dupe-args": ["error"],
+        "no-dupe-else-if": ["error"],
+        "no-unsafe-negation": ["error"],
+        "no-duplicate-imports": ["error"],
+        "valid-typeof": ["error"],
+        "@typescript-eslint/no-unused-vars": ["error", { "vars": "all", "args": "none", "ignoreRestSiblings": false, "caughtErrors": "all" }],
+        "no-restricted-syntax": [
+            "error",
+            {
+                "selector": "MemberExpression[object.name='test'][property.name='only']",
+                "message": "test.only(...) is forbidden",
+            },
+            {
+                "selector": "MemberExpression[object.name='describe'][property.name='only']",
+                "message": "describe.only(...) is forbidden",
+            }
+        ],
+    },
+    "globals": {
+        "describe": true,
+        "expect": true,
+        "test": true,
+        "beforeEach": true,
+        "beforeAll": true,
+        "afterEach": true,
+        "afterAll": true,
+        "jest": true,
+    },
+}

.github/workflows/deploy.yml

@@ -5,7 +5,7 @@ name: Node.js CI
 
 on:
   pull_request:
-    branches: [ master, owl-next ]
+    branches: [ master ]
 
 jobs:
   build:
@@ -22,7 +22,8 @@ jobs:
       uses: actions/setup-node@v1
       with:
         node-version: ${{ matrix.node-version }}
-    - run: npm install
+    - run: npm ci
     - run: npm run test
     - run: npm run check-formatting
+    - run: npm run lint
     - run: npm run build

.gitignore

@@ -14,9 +14,6 @@ npm-debug.log*
 yarn-debug.log*
 yarn-error.log*
 
-package-lock.json
-yarn.lock
-
 #ide's
 .vscode
 .idea

CHANGELOG.md

@@ -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
+Migration code: remove the `shouldUpdate` methods, and it should work as well
-ideas may help:
+as before.
-
-- 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>
-  ```
 
 ### 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
+In Owl, a call to `useSubEnv` would define a new environment for the children
-AND the component. It now only defines an 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:
-Rationale: This was a subtle cause for bugs: some code had to be rrun
+[`useChildSubEnv`](doc/reference/hooks.md#usesubenv-and-usechildsubenv)
-before the call to `useSubEnv`, otherwise it could interfere with the sub environment.
-
-Documentation: [Hooks](doc/reference/hooks.md#usesubenv)
 
 ### 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.
+

README.md

@@ -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](https://github.com/odoo/owl/releases/latest)
 

doc/learning/tutorial_todoapp.md

@@ -174,9 +174,9 @@ class Root extends Component {
 ```
 
 The template contains a [`t-foreach`](../reference/templates.md#loops) loop to iterate
-through the tasks. It can find the `tasks` list from the component, since the
+through the tasks. It can find the `tasks` list from the component, since the rendering
-component is the rendering context. Note that we use the `id` of each task as a
+context contains the properties of the component. Note that we use the `id` of each task
-`t-key`, which is very common. There are two css classes: `task-list` and `task`,
+as a `t-key`, which is very common. There are two css classes: `task-list` and `task`,
 that we will use in the next section.
 
 Finally, notice the use of the `t-att-checked` attribute:
@@ -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"];
 }
@@ -502,6 +502,10 @@ deleteTask(task) {
 Notice that the `onDelete` prop is defined with a `.bind` suffix: this is a special
 suffix that makes sure the function callback is bound to the component.
 
+Notice also that we have two functions named `deleteTask`. The one in the Task
+component just delegates the work to the Root component that owns the task list
+via the `onDelete` property.
+
 ## 10. Using a store
 
 Looking at the code, it is apparent that all the code handling tasks is scattered
@@ -743,7 +747,7 @@ 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>
 ```
 
@@ -770,10 +774,11 @@ For reference, here is the final code:
     <meta charset="UTF-8" />
     <title>OWL Todo App</title>
     <link rel="stylesheet" href="app.css" />
+  </head>
+  <body>
     <script src="owl.js"></script>
     <script src="app.js"></script>
-  </head>
+  </body>
-  <body></body>
 </html>
 ```
 

doc/miscellaneous/compiled_template.md

@@ -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.

doc/readme.md

@@ -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

doc/reference/app.md

@@ -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.
+  an instance), and the optional second argument is a configuration object (see below).
-
-  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.
 
 - **`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

doc/reference/component.md

@@ -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

doc/reference/context.md

@@ -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.

doc/reference/environment.md

@@ -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 {

doc/reference/event_bus.md

@@ -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          |

doc/reference/event_handling.md

@@ -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).

doc/reference/hooks.md

@@ -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
+The `useSubEnv` and `useChildSubEnv` hooks take one argument: an object which
-will be added to the parent environment. Note that it will extend, not replace
+contains some key/value that will be added to the current environment. These hooks
-the parent environment. And of course, the parent environment will not be
+will create a new env object with the new information:
-affected.
+
+- `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`
 
@@ -223,7 +234,8 @@ are defined by a function instead of just the dependencies.
 
 The `useEffect` hook takes two function: the effect function and the dependency
 function. The effect function perform some task and return (optionally) a cleanup
-function. The dependency function returns a list of dependencies. If any of these
+function. The dependency function returns a list of dependencies, these dependencies
+are passed as parameters in the effect function . If any of these
 dependencies changes, then the current effect will be cleaned up and reexecuted.
 
 Here is an example without any dependencies:

doc/reference/precompiling_templates.md

@@ -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.

doc/reference/props.md

@@ -159,6 +159,7 @@ For each key, a `prop` definition is either a boolean, a constructor, a list of
 - a boolean: indicate that the props exists, and is mandatory.
 - a constructor: this should describe the type, for example: `id: Number` describe
   the props `id` as a number
+- an object describing a value as type. This is done by using the `value` key. For example, `{value: false}` specifies that the corresponding value should be equal to false.
 - a list of constructors. In that case, this means that we allow more than one
   type. For example, `id: [Number, String]` means that `id` can be either a string
   or a number.
@@ -168,11 +169,15 @@ 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 +195,8 @@ 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 }
   };
 
   ...
@@ -235,9 +241,12 @@ class ComponentB extends owl.Component {
     size: {
       validate:  e => ["small", "medium", "large"].includes(e)
     },
+    someId: [Number, {value: false}], // either a number or false
   };
 ```
 
+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,

doc/reference/reactivity.md

@@ -2,79 +2,394 @@
 
 ## Content
 
-- [Overview](#overview)
+- [Introduction](#introduction)
 - [`useState`](#usestate)
 - [`reactive`](#reactive)
+- [`Escape hatches`](#escape-hatches)
+- [`Advanced usage`](#advanced-usage)
 
-## Overview
+## Introduction
 
 Reactivity is a big topic in javascript frameworks. The goal is to provide a
-simple way to manipulate state, in such a way that the interface automatically
+simple way to manipulate state, in such a way that the interface updates automatically
-update accordingly to state changes. Also, we obviously want this to happen in
+according to state changes, and to do so in a performant manner.
-a performant way.
 
-To solve this issue, Owl provides two reactivity primitives:
+To this end, Owl provides a proxy-based reactivity system, based on the `reactive` primitive.
-
+The `reactive` function takes an object as a first argument, and an optional callback as its second
-- `reactive`, which returns a proxy to its first argument, and tracks all read/update
+argument, it returns a proxy of the object. This proxy tracks what properties are read
-  operation going through it,
+through the proxy, and calls the provided callback whenever one of these properties is changed
-- `useState`: a hook, that internally uses `reactive`, and is linked to its
+through any reactive version of the same object. It does so in depth, by returning reactive versions
-  owner component: any read operation will be tracked (key by key), and any
+of the subobjects when they are read.
-  updates to these tracked values will cause the component to be rerendered.
-
-Most of the time, the `useState` hook is the best solution.
 
 ## `useState`
 
-Let us start by an example of how `useState` could be used:
+While the `reactive` primitive is very powerful, its usage in components follow a very standard pattern:
+components want to be rerendered when part of the state which they depend on for rendering changes. To
+this end, owl provides a standard hook: `useState`. To put it simply, this hook simply calls reactive
+with the provided object, and the current component's render function as its callback. This will cause
+it to rerender whenever any part of the state object that has been read by this component is modified.
+
+Here is a simple example of how `useState` can be used:
 
 ```js
 class Counter extends Component {
   static template = xml`
-    <div t-on-click="increment">
+    <div t-on-click="() => this.state.value++">
       <t t-esc="state.value"/>
     </div>`;
 
   setup() {
     this.state = useState({ value: 0 });
   }
+}
+```
 
-  increment() {
+This component reads `state.value` when it renders, subscribing it to changes to that key. Whenever
-    this.state.value++;
+the value changes, Owl will update the component. Note that there is nothing special about the
+`state` property, you can name your state variables whatever you want, and you can have multiple of
+them on the same component if it makes sense to do so. This also allows `useState` to be used in custom
+hooks that may require state that is specific to that hook.
+
+### Reactive props
+
+Since version 2.0, Owl renders are no longer "deep" by default: a component is only rerendered by its
+parent if its props have changed (using a simple equality test). What if the contents of a props have
+changed in a deeper property? If that prop is reactive, owl will rerender the child components that
+need to be updated automatically, and only those components, it does so by reobserving reactive
+objects passed as props to components. Consider the following example:
+
+```js
+class Counter extends Component {
+  static template = xml`
+    <div t-on-click="() => props.state.value++">
+      <t t-esc="props.state.value"/>
+    </div>`;
+}
+
+class Parent extends Component {
+  static template = xml`
+    <Counter state="this.state"/>
+    <button t-on-click="() => this.state.value = 0">Reset counter</button>
+    <button t-on-click="() => this.state.test++" t-esc="this.state.test"/>`;
+
+  setup() {
+    this.state = useState({ value: 0, test: 1 });
   }
 }
 ```
 
-If one were to use a simple state object, Owl would not be aware that the value
+When clicking on the counter button, only the Counter rerenders, because the Parent has never read
-was changed and that the component should be rerendered. With the `useState`
+the "value" key in the state. When clicking on the "Reset Counter" button, the same thing happens:
-hook, `this.state` is now a reactive object, so this component works as expected.
+only the Counter component rerenders. What matters is not _where_ the state is updated, but which
+parts of the state are updated, and which components depend on them. This is achieved by Owl by
+automatically calling `useState` on reactive objects passed as props to a child component.
+
+When clicking on the last button, the parent is rerendered, but the child does not care about the
+`test` key: it has not read it. The props that we give it (`this.state`) have also not changed,
+as such, the parent updates but the child doesn't.
+
+For most day-to-day operations, `useState` should cover all of your needs. If
+you are curious about more advanced use cases and technical details, read on.
+
+### Debugging subscriptions
+
+Owl provides a way to show which reactive objects and keys a component is subscribed to: you can
+look at `component.__owl__.subscriptions`. Note that this is on the internal `__owl__` field, and
+should not be used in any type of production code as the name of this property or any of its properties
+or methods are subject to change at any point, even in stable versions of Owl, and may become available
+only in debug mode in the future.
 
 ## `reactive`
 
 The `reactive` function is the basic reactivity primitive. It takes an object
 or an array as first argument, and optionally, a function as the second argument.
-The function will be called whenever any tracked value is updated.
+The function is called whenever any tracked value is updated.
 
 ```js
 const obj = reactive({ a: 1 }, () => console.log("changed"));
 
-obj.a = 2; // does not log anything: the 'a' key was not read
+obj.a = 2; // does not log anything: the 'a' key has not been read yet
-console.log(obj.a); // log 2, and reads the 'a' key => it is now tracked
+console.log(obj.a); // logs 2 and reads the 'a' key => it is now tracked
-obj.a = 3; // log 'changed' because we updated a tracked value
+obj.a = 3; // logs 'changed' because we updated a tracked value
 ```
 
 An important property of reactive objects is that they can be reobserved: this
-will create an independant proxy that tracks another set of keys:
+will create an independent proxy that tracks another set of keys:
 
 ```js
 const obj1 = reactive({ a: 1, b: 2 }, () => console.log("observer 1"));
 const obj2 = reactive(obj1, () => console.log("observer 2"));
 
-console.log(obj1.a); // log 1, and reads the 'a' key => it is now tracked by observer 1
+console.log(obj1.a); // logs 1, and reads the 'a' key => it is now tracked by observer 1
-console.log(obj1.b); // log 2, and 'b' is now tracked by observer 1
+console.log(obj2.b); // logs 2, and 'b' is now tracked by observer 2
-console.log(obj2.b); // log 2, and 'b' is now tracked by observer 1
+obj2.a = 3; // only logs 'observer1', because observer2 does not track a
-obj2.a = 3; // log 'observer1', because observer2 does not track a
+obj2.b = 3; // only logs 'observer2', because observer1 does not track b
-obj2.b = 3; // log 'observer1' and 'observer2'
+console.log(obj2.a, obj1.b); // logs 3 and 3, while the object is observed independently, it is still a single object
 ```
 
-Obviously, one can use `reactive` on the result of a `useState` if wanted, this
+Because `useState` returns a normal reactive object, it is possible to call `reactive` on the result
-is the proper way to watch for some state changes.
+of a `useState` to observe changes to that object while outside the context of a component, or to
+call `useState` on reactive objects created outside of components. In those cases, one needs to be
+careful with regards to the lifetime of those reactive objects, as holding references to these
+objects may prevent garbage collection of the component and its data even if Owl has destroyed it.
+
+### Subscriptions are ephemereal
+
+Subscription to state changes are ephemereal, whenever an observer is notified that a state object
+has changed, all of its subscriptions are cleared, meaning that if it still cares about it, it
+should read the properties it cares about again. For example:
+
+```js
+const obj = reactive({ a: 1 }, () => console.log("observer called"));
+
+console.log(obj.a); // logs 1, and reads the 'a' key => it is now tracked by the observer
+obj.a = 3; // logs 'observer1' and clears the subscriptions of the observer
+obj.a = 4; // doesn't log anything, the key is no longer observed
+```
+
+This may seem counter-intuitive, but it makes perfect sense in the context of components:
+
+```js
+class DoubleCounter extends Component {
+  static template = xml`
+    <t t-esc="state.selected + ': ' + state[state.selected].value"/>
+    <button t-on-click="() => this.state.count1++">increment count 1</button>
+    <button t-on-click="() => this.state.count2++">increment count 2</button>
+    <button t-on-click="changeCounter">Switch counter</button>
+  `;
+
+  setup() {
+    this.state = useState({ selected: "count1", count1: 0, count2: 0 });
+  }
+
+  changeCounter() {
+    this.state.selected = this.state.selected === "count1" ? "count2" : "count1";
+  }
+}
+```
+
+In this component, if we increment the value of the second counter, the component will not rerender,
+which makes sense as rerendering will have no effect, as the second counter is not displayed. If we
+toggle the component to display the second counter, we now no longer want the component to rerender
+when the value of the first counter changes, and this is what happens: a component only rerenders
+when there are changes to pieces of state that have been read during or after the previous render.
+If a piece of state has not been read in the last render, we know that its value won't influence the
+rendered output, and so we can ignore it.
+
+### reactive `Map` and `Set`
+
+The reactivity system has special support built-in for the standard container types `Map` and `Set`.
+They behave like one would expect: reading a key subscribes the observer to that key, adding or
+removing an item to them notifies observers that have used any of the iterators on that reactive
+object, such as `.entries()` or `.keys()`, likewise with clearing them.
+
+## Escape hatches
+
+Sometimes, it is desirable to bypass the reactivity system. Creating proxies when interacting with
+reactive objects is expensive, and while on the whole, the performance benefit that we get by
+rerendering only the parts of the interface that need it outweighs that cost, in some cases, we want
+to be able to opt out of creating them in the first place. This is the purpose of `markRaw`:
+
+### `markRaw`
+
+Marks an object so that it is ignored by the reactivity system, meaning that if this object is ever
+part of a of a reactive object, it will be returned as is, and no keys in that object will be
+observed.
+
+```js
+const someObject = markRaw({ b: 1 });
+const state = useState({
+  a: 1,
+  obj: someObject,
+});
+console.log(state.obj.b); // attempt to subscribe to the "b" key in someObject
+state.obj.b = 2; // No rerender will occur here
+console.log(someObject === state.obj); // true
+```
+
+This is useful in some rare cases. One such example would be if you want to use an array of objects
+that is potentially large to render a list, but those objects are known to be immutable:
+
+```js
+this.items = useState([
+  { label: "some text", value: 42 },
+  // ... 1000 total objects
+]);
+```
+
+in the template:
+
+```xml
+<t t-foreach="items" t-as="item" t-key="item.label" t-esc="item.label + item.value"/>
+```
+
+Here, on every render, we go and read one thousand keys from a reactive object, which causes
+one thousand reactive objects to be created. If we know that the content of these objects
+cannot change, this is wasted work. If instead all of these objects are marked as raw, we avoid
+all of this work while keeping the ability to lean on the reactivity to track the presence and
+identity of these objects:
+
+```js
+this.items = useState([
+  markRaw({ label: "some text", value: 42 }),
+  // ... 1000 total objects
+]);
+```
+
+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! For example:
+
+```js
+// This will cause a rerender
+this.items.push(markRaw({ label: "another label", value: 1337 }));
+
+// THIS WILL NOT CAUSE A RENDER!
+this.items[17].value = 3;
+// The UI is now desynced from component's state until the next render caused by something else
+```
+
+In short: only use `markRaw` if your application is slowing down noticeably and profiling reveals
+that a lot of time is spent creating useless reactive objects.
+
+### `toRaw`
+
+While `markRaw` marks an object so that it is never made reactive, `toRaw` takes an object and
+returns the underlying non-reactive object. It can be useful in some niche cases. In particular,
+because the reactivity system returns a proxy, the returned object does not compare equal to the
+original object:
+
+```js
+const obj = {};
+const reactiveObj = reactive(obj);
+console.log(obj === reactiveObj); // false
+console.log(obj === toRaw(reactiveObj)); // true
+```
+
+It can also be useful during debugging, as unfolding proxies recursively in debuggers can be confusing.
+
+## Advanced usage
+
+The following is a collection of small snippets that leverage the reactivity system in
+"non-standard" ways to help you understand its power and where using it might make your code simpler.
+
+### Notification manager
+
+Showing notifications is a pretty common need in web applications, you may want to show a
+notification from any other component within the application, and the notifications should stack on
+top of one another regardless of which component spawned them, here is how we can leverage the
+reactivity to accomplish this:
+
+```js
+let notificationId = 1;
+const notifications = reactive({});
+class NotificationContainer extends Component {
+  static template = xml`
+    <t t-foreach="notifications" t-as="notification" t-key="notification_key" t-esc="notification"/>
+  `;
+  setup() {
+    this.notifications = useState(notifications);
+  }
+}
+
+export function addNotification(label) {
+  const id = notificationId++;
+  notifications[id] = label;
+  return () => {
+    delete notifications[id];
+  };
+}
+```
+
+Here, the `notifications` variable is a reactive object. Notice how we didn't give `reactive` a
+callback: this is because in this case, all we care about is that adding or removing notifications
+in the `addNotification` function goes through the reactivity system. The `NotificationContainer`
+component reobserves this object with `useState`, and is updated whenever notifications are
+added or removed.
+
+### Store
+
+Centralizing application state is a pretty common want/need in web applications. Because of the way
+the reactivity system works, you can treat any reactive object as a store, and if you call `useState`
+on it, components automatically observe only the part of the store that they're interested in:
+
+```js
+export const store = reactive({
+  list: [],
+  add(item) {
+    this.list.push(item);
+  },
+});
+
+export function useStore() {
+  return useState(store);
+}
+```
+
+In any component:
+
+```js
+import { useStore } from "./store";
+
+class List extends Component {
+  static template = xml`
+    <t t-foreach="store.list" t-as="item" t-key="item" t-esc="item"/>
+  `;
+  setup() {
+    this.store = useStore();
+  }
+}
+```
+
+Anywhere in the application:
+
+```js
+import { store } from "./store";
+// Will cause any instance of the List component in the app to update
+store.add("New list item!");
+```
+
+Notice how we can make objects with methods into reactive objects, and when these methods are used
+to mutate the store contents, it works as expected. And while stores are generally one-off objects,
+it is entirely possible to make class instances reactive:
+
+```js
+class Store {
+  list = [];
+  add(item) {
+    this.list.push(item);
+  }
+}
+// Essentially equivalent to the previous code
+export const store = reactive(new Store());
+```
+
+Which can be useful to unit test the class separately.
+
+### Local storage synchronization
+
+Sometimes, you want to persist some state accross reloads, you can do this by storing it in the
+`localStorage`, but what if you want to update the `localStorage` item every time the state changes,
+so that you don't have to manually synchronize the states? Well, you can use the reactivity system
+to write a custom hook that will do that for you:
+
+```js
+function useStoredState(key, initialState) {
+  const state = JSON.parse(localStorage.getItem(key)) || initialState;
+  const store = (obj) => localStorage.setItem(key, JSON.stringify(obj));
+  const reactiveState = reactive(state, () => store(reactiveState));
+  store(reactiveState);
+  return useState(state);
+}
+
+class MyComponent extends Component {
+  setup() {
+    this.state = useStoredState("MyComponent.state", { value: 1 });
+  }
+}
+```
+
+One important thing to notice is that both times we call `store`, we call it with `reactiveState`,
+not `state`: we need `store` to read the keys through a reactive object for it to correctly
+subscribe to state changes. Notice also that we call `store` the first time by hand, as otherwise it
+will not be subscribed to anything, and no amount of change in the object will cause the reactive
+callback to be invoked.

doc/reference/slots.md

@@ -87,8 +87,8 @@ grandparent of the slot content).
 
 ## Default Slot
 
-The first element inside the component which is not a named slot will
+All elements inside the component which are not a named slot will be treated as
-be considered the `default` slot. For example:
+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
+For other kinds of advanced use cases, the content of a slot may depends on some
-specific information specific to the generic component. This is the opposite
+information specific to the generic component. This is the opposite of the slot
-of the slot params.
+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>
+<MyComponent>
-    <t t-set-slot="foo" t-set-scope="scope">
+    <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">
-    <t t-slot="foo" bool="other_var" num="5">
-</div>
 ```
+
+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.

doc/reference/templates.md

@@ -21,6 +21,7 @@
 - [Fragments](#fragments)
 - [Inline templates](#inline-templates)
 - [Rendering svg](#rendering-svg)
+- [Restrictions](#restrictions)
 
 ## Overview
 
@@ -114,7 +115,7 @@ It is useful to explain the various rules that apply on these expressions:
    <div><p t-if="console.log(1)">NOT valid</p></div>
    ```
 
-2. it can use anything in the rendering context (typically, the component):
+2. it can use anything in the rendering context (which typically contains the properties of the component):
 
    ```xml
    <p t-if="user.birthday === today()">Happy bithday!</p>
@@ -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> -->
 ```
 
@@ -538,6 +540,14 @@ This can be used to define variables scoped to a sub template:
 <!-- "var" does not exist here -->
 ```
 
+Note: by default, the rendering context for a sub template is simply the current
+rendering context. However, it may be useful to be able to specify a specific
+object as context. This can be done by using the `t-call-context` directive:
+
+```xml
+<t t-call="other-template" t-call-context="obj"/>
+```
+
 ### Dynamic sub templates
 
 The `t-call` directive can also be used to dynamically call a sub template,
@@ -674,7 +684,19 @@ 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
+**Important note:** Owl needs to properly set the namespace for each svg elements.
-to be properly set), there is a small constraint for Owl components: if an owl
+Since Owl compile each template separately, it is not able to determine easily
-component is supposed to be a part of an svg graph, then its root node needs to
+if a template is supposed to be included in a svg namespace or not. Therefore,
-be a `g` tag, so Owl can properly set the namespace.
+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>
+```

doc/reference/translations.md

@@ -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...
+```

doc/reference/utils.md

@@ -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),
+```

package.json

@@ -1,11 +1,10 @@
 {
   "name": "@odoo/owl",
-  "version": "2.0.0-alpha1",
+  "version": "2.0.7",
   "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 +13,8 @@
   },
   "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",
@@ -24,8 +25,10 @@
     "playground:watch": "npm-run-all  --parallel playground:serve \"build:* -- --watch\"",
     "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",
+    "lint": "eslint src/**/*.ts tests/**/*.ts",
     "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",
@@ -40,25 +43,25 @@
   "devDependencies": {
     "@types/jest": "^27.0.1",
     "@types/node": "^14.11.8",
+    "@typescript-eslint/eslint-plugin": "5.48.1",
+    "@typescript-eslint/parser": "5.48.1",
     "chalk": "^3.0.0",
-    "cpx": "^1.5.0",
     "current-git-branch": "^1.1.0",
-    "git-rev-sync": "^1.12.0",
+    "eslint": "8.31.0",
+    "git-rev-sync": "^3.0.2",
     "github-api": "^3.3.0",
     "jest": "^27.1.0",
     "jest-diff": "^27.3.1",
     "jest-environment-jsdom": "^27.1.0",
-    "live-server": "^1.2.1",
     "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",
     "source-map-support": "^0.5.10",
     "ts-jest": "^27.0.5",
-    "typescript": "4.5.2",
+    "typescript": "4.5.2"
-    "uglify-es": "^3.3.9"
   },
   "jest": {
     "testEnvironment": "jsdom",

roadmap.md

@@ -1,28 +1,9 @@
 # 🦉 OWL Roadmap 🦉
 
-- Current version: 1.4.7
+- Current version: 2.X
 - Status: stable
 
-This roadmap is only an attempt at predicting Owl's future.  Everything may
+Owl is currently stable. No (large) improvements is expected in the near future.
-change!
-
-
-### 1.x
-
-- add chrome and firefox devtools,
-- fix every bugs,
-- improve documentation,
-- small backward compatible improvements.
-
-### 2.x (2020? 2021? 2022?)
-
-- stop support for `t-set` directive to define the content of a slot
-
-Maybe:
-
-- reimplement vdom to use *block* system, like Vue 3, which should make Owl
-  much faster
-- refactor `QWeb` to use an intermediate representation (some kind of AST) to
-  allow additional optimisations.
-
 
+Note that we intend to keep maintaining owl, and as such, improvements and/or
+breaking changes may require a version bump in the future.

rollup.config.js

@@ -2,14 +2,18 @@ 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";
+let input, output;
-const extend = true;
+
+const IIFE_FILENAME = "dist/owl.iife.js";
+const CJS_FILENAME = "dist/owl.cjs.js";
+const ES_FILENAME = "dist/owl.es.js";
+
+if (pkg.module !== ES_FILENAME || pkg.main !== CJS_FILENAME) {
+  throw new Error("package.json has been modified. Build script should be updated accordingly");
+}  
 
-/**
- * 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 +21,39 @@ __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(ES_FILENAME,  'runtime'), outro),
+      getConfigForFormat('cjs', addSuffix(CJS_FILENAME,  'runtime'), outro),
+      getConfigForFormat('iife', addSuffix(IIFE_FILENAME,  'runtime'), outro),
+      getConfigForFormat('iife', addSuffix(IIFE_FILENAME,  'runtime'), outro, true),
+    ]
+    break;
+  default:
+    input = "src/index.ts",
+    output = [
+      getConfigForFormat('esm', ES_FILENAME, outro),
+      getConfigForFormat('cjs', CJS_FILENAME, outro),
+      getConfigForFormat('iife', IIFE_FILENAME, outro),
+      getConfigForFormat('iife', IIFE_FILENAME, 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 +63,12 @@ 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,
+    name: "owl",
-    extend: extend,
+    extend: true,
     outro: outro,
     freeze: false,
     plugins: minified ? [terser()] : [],
@@ -46,26 +76,19 @@ function getConfigForFormat(format, generatedFileName, minified = false) {
   };
 }
 
-export default {
+export default [
-  input: "src/index.ts",
+  {
-  output: [
+    input,
-
+    output,
-    /**
+    plugins: [
-     * Read about module formats:
+      typescript({
-     *  https://auth0.com/blog/javascript-module-systems-showdown/
+        useTsconfigDeclarationDir: true
-     *  https://medium.com/@kelin2025/so-you-wanna-use-es6-modules-714f48b3a953
+      }),
-     */
+    ]
-
+  },
-    getConfigForFormat('esm', pkg.module),
+  {
-    getConfigForFormat('esm', pkg.module, true),
+    input: "dist/types/index.d.ts",
-    getConfigForFormat('cjs', pkg.main),
+    output: [{ file: "dist/types/owl.d.ts", format: "es" }],
-    getConfigForFormat('cjs', pkg.main, true),
+    plugins: [dts()],
-    getConfigForFormat('iife', pkg.browser),
+  },
-    getConfigForFormat('iife', pkg.browser, true),
+];
-  ],
-  plugins: [
-    typescript({
-      useTsconfigDeclarationDir: true
-    }),
-  ]
-};

src/app/app.ts

@@ -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);
-}

src/app/template_helpers.ts

@@ -1,203 +0,0 @@
-import { BDom, multi, text, toggler } from "../blockdom";
-import { validateProps } from "../component/props_validation";
-import { Markup } from "../utils";
-import { html } from "../blockdom/index";
-import { TARGET } from "../reactivity";
-
-/**
- * This file contains utility functions that will be injected in each template,
- * to perform various useful tasks in the compiled code.
- */
-
-function withDefault(value: any, defaultValue: any): any {
-  return value === undefined || value === null || value === false ? defaultValue : value;
-}
-
-function callSlot(
-  ctx: any,
-  parent: any,
-  key: string,
-  name: string,
-  dynamic: boolean,
-  extra: any,
-  defaultContent?: (ctx: any, node: any, key: string) => BDom
-): BDom {
-  key = key + "__slot_" + name;
-  const nonReactiveProps = ctx.props && ctx.props[TARGET];
-  const slots = nonReactiveProps ? nonReactiveProps.slots || {} : {};
-  const { __render, __ctx, __scope } = slots[name] || {};
-  const slotScope = Object.create(__ctx || {});
-  if (__scope) {
-    slotScope[__scope] = extra || {};
-  }
-  const slotBDom = __render ? __render.call(__ctx.__owl__.component, slotScope, parent, key) : null;
-  if (defaultContent) {
-    let child1: BDom | undefined = undefined;
-    let child2: BDom | undefined = undefined;
-    if (slotBDom) {
-      child1 = dynamic ? toggler(name, slotBDom) : slotBDom;
-    } else {
-      child2 = defaultContent.call(ctx.__owl__.component, ctx, parent, key);
-    }
-    return multi([child1, child2]);
-  }
-  return slotBDom || text("");
-}
-
-function capture(ctx: any): any {
-  const component = ctx.__owl__.component;
-  const result = Object.create(component);
-  for (let k in ctx) {
-    result[k] = ctx[k];
-  }
-  return result;
-}
-
-function withKey(elem: any, k: string) {
-  elem.key = k;
-  return elem;
-}
-
-function prepareList(collection: any): [any[], any[], number, any[]] {
-  let keys: any[];
-  let values: any[];
-
-  if (Array.isArray(collection)) {
-    keys = collection;
-    values = collection;
-  } else if (collection) {
-    values = Object.keys(collection);
-    keys = Object.values(collection);
-  } else {
-    throw new Error("Invalid loop expression");
-  }
-  const n = values.length;
-  return [keys, values, n, new Array(n)];
-}
-
-const isBoundary = Symbol("isBoundary");
-
-function setContextValue(ctx: { [key: string]: any }, key: string, value: any): void {
-  const ctx0 = ctx;
-  while (!ctx.hasOwnProperty(key) && !ctx.hasOwnProperty(isBoundary)) {
-    const newCtx = ctx.__proto__;
-    if (!newCtx) {
-      ctx = ctx0;
-      break;
-    }
-    ctx = newCtx;
-  }
-  ctx[key] = value;
-}
-
-function toNumber(val: string): number | string {
-  const n = parseFloat(val);
-  return isNaN(n) ? val : n;
-}
-
-function shallowEqual(l1: any[], l2: any[]): boolean {
-  for (let i = 0, l = l1.length; i < l; i++) {
-    if (l1[i] !== l2[i]) {
-      return false;
-    }
-  }
-  return true;
-}
-
-class LazyValue {
-  fn: any;
-  ctx: any;
-  node: any;
-  constructor(fn: any, ctx: any, node: any) {
-    this.fn = fn;
-    this.ctx = capture(ctx);
-    this.node = node;
-  }
-
-  evaluate(): any {
-    return this.fn(this.ctx, this.node);
-  }
-
-  toString() {
-    return this.evaluate().toString();
-  }
-}
-
-/*
- * Safely outputs `value` as a block depending on the nature of `value`
- */
-export function safeOutput(value: any): ReturnType<typeof toggler> {
-  if (!value) {
-    return value;
-  }
-  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;
-  }
-  return toggler(safeKey, block);
-}
-
-let boundFunctions = new WeakMap();
-
-function bind(ctx: any, fn: Function): Function {
-  let component = ctx.__owl__.component;
-  let boundFnMap = boundFunctions.get(component);
-  if (!boundFnMap) {
-    boundFnMap = new WeakMap();
-    boundFunctions.set(component, boundFnMap);
-  }
-  let boundFn = boundFnMap.get(fn);
-  if (!boundFn) {
-    boundFn = fn.bind(component);
-    boundFnMap.set(fn, boundFn);
-  }
-  return boundFn;
-}
-
-type RefMap = { [key: string]: HTMLElement | null };
-type RefSetter = (el: HTMLElement | null) => void;
-
-function multiRefSetter(refs: RefMap, name: string): RefSetter {
-  let count = 0;
-  return (el) => {
-    if (el) {
-      count++;
-      if (count > 1) {
-        throw new Error("Cannot have 2 elements with same ref name at the same time");
-      }
-    }
-    if (count === 0 || el) {
-      refs[name] = el;
-    }
-  };
-}
-
-export const UTILS = {
-  withDefault,
-  zero: Symbol("zero"),
-  isBoundary,
-  callSlot,
-  capture,
-  withKey,
-  prepareList,
-  setContextValue,
-  multiRefSetter,
-  shallowEqual,
-  toNumber,
-  validateProps,
-  LazyValue,
-  safeOutput,
-  bind,
-};

src/compiler/index.ts

@@ -1,15 +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;
 }
-export function compile(template: string | Node, options: CompileOptions = {}): TemplateFunction {
+export function compile(
+  template: string | Element,
+  options: CompileOptions = {}
+): TemplateFunction {
   // parsing
   const ast = parse(template);
 
@@ -23,5 +27,5 @@ export function compile(template: string | Node, options: CompileOptions = {}):
   const codeGenerator = new CodeGenerator(ast, { ...options, hasSafeContext });
   const code = codeGenerator.generateCode();
   // template function
-  return new Function("bdom, helpers", code) as TemplateFunction;
+  return new Function("app, bdom, helpers", code) as TemplateFunction;
 }

src/compiler/inline_expressions.ts

@@ -1,3 +1,5 @@
+import { OwlError } from "../runtime/error_handling";
+
 /**
  * Owl QWeb Expression Parser
  *
@@ -26,7 +28,7 @@
 //------------------------------------------------------------------------------
 
 const RESERVED_WORDS =
-  "true,false,NaN,null,undefined,debugger,console,window,in,instanceof,new,function,return,this,eval,void,Math,RegExp,Array,Object,Date".split(
+  "true,false,NaN,null,undefined,debugger,console,window,in,instanceof,new,function,return,eval,void,Math,RegExp,Array,Object,Date".split(
     ","
   );
 
@@ -85,8 +87,9 @@ 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
+// expression has a space after typeof. Currently we don't support delete and void
-const OPERATORS = "...,.,===,==,+,!==,!=,!,||,&&,>=,>,<=,<,?,-,*,/,%,typeof ,=>,=,;,in ".split(",");
+const OPERATORS =
+  "...,.,===,==,+,!==,!=,!,||,&&,>=,>,<=,<,?,-,*,/,%,typeof ,=>,=,;,in ,new ,|,&,^,~".split(",");
 
 type Tokenizer = (expr: string) => Token | false;
 
@@ -105,14 +108,14 @@ let tokenizeString: Tokenizer = function (expr) {
       i++;
       cur = expr[i];
       if (!cur) {
-        throw new Error("Invalid expression");
+        throw new OwlError("Invalid expression");
       }
       s += cur;
     }
     i++;
   }
   if (expr[i] !== start) {
-    throw new Error("Invalid expression");
+    throw new OwlError("Invalid expression");
   }
   s += start;
   if (start === "`") {
@@ -199,24 +202,30 @@ const TOKENIZERS = [
 export function tokenize(expr: string): Token[] {
   const result: Token[] = [];
   let token: boolean | Token = true;
+  let error: any;
+  let current = expr;
 
-  while (token) {
+  try {
-    expr = expr.trim();
+    while (token) {
-    if (expr) {
+      current = current.trim();
-      for (let tokenizer of TOKENIZERS) {
+      if (current) {
-        token = tokenizer(expr);
+        for (let tokenizer of TOKENIZERS) {
-        if (token) {
+          token = tokenizer(current);
-          result.push(token);
+          if (token) {
-          expr = expr.slice(token.size || token.value.length);
+            result.push(token);
-          break;
+            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) {
+  if (current.length || error) {
-    throw new Error(`Tokenizer error: could not tokenize "${expr}"`);
+    throw new OwlError(`Tokenizer error: could not tokenize \`${expr}\``);
   }
   return result;
 }
@@ -329,28 +338,38 @@ 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;
+export const INTERP_REGEXP = /\{\{.*?\}\}|\#\{.*?\}/g;
-const INTERP_GROUP_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);
+}

src/compiler/parser.ts

@@ -1,7 +1,12 @@
+import { OwlError } from "../runtime/error_handling";
+
 // -----------------------------------------------------------------------------
 // AST Type definition
 // -----------------------------------------------------------------------------
 
+export type EventHandlers = { [eventName: string]: string };
+export type Attrs = { [attrs: string]: string };
+
 export const enum ASTType {
   Text,
   Comment,
@@ -18,6 +23,7 @@ export const enum ASTType {
   TDebug,
   TLog,
   TSlot,
+  TSetSlot,
   TCallBlock,
   TTranslation,
   TPortal,
@@ -33,23 +39,26 @@ 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 };
+  on: EventHandlers | null;
-  model: {
+  model: TModelInfo | null;
-    baseExpr: string;
+  dynamicTag: string | null;
-    expr: string;
-    targetAttr: string;
-    specialInitTargetAttr: string | null;
-    eventType: "change" | "click" | "input";
-    shouldTrim: boolean;
-    shouldNumberize: boolean;
-  } | null;
   ns: string | null;
 }
 
@@ -90,13 +99,13 @@ 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 {
@@ -109,6 +118,16 @@ export interface ASTTCall {
   type: ASTType.TCall;
   name: string;
   body: AST[] | null;
+  context: string | null;
+}
+
+export interface ASTSlotDefinition {
+  type: ASTType.TSetSlot;
+  name: string;
+  content: AST | null;
+  scope: string | null;
+  on: EventHandlers | null;
+  attrs: Attrs | null;
 }
 
 export interface ASTComponent {
@@ -116,14 +135,17 @@ export interface ASTComponent {
   name: string;
   isDynamic: boolean;
   dynamicProps: string | null;
-  props: { [name: string]: string };
+  on: EventHandlers | null;
-  slots: { [name: string]: { content: AST; attrs?: { [key: string]: string }; scope?: string } };
+  props: { [name: string]: string } | null;
+  body: AST | null;
+  // slots: { [name: string]: ASTSlotDefinition } | null;
 }
 
 export interface ASTSlot {
   type: ASTType.TSlot;
   name: string;
-  attrs: { [key: string]: string };
+  attrs: Attrs | null;
+  on: EventHandlers | null;
   defaultContent: AST | null;
 }
 
@@ -168,6 +190,7 @@ export type AST =
   | ASTTKey
   | ASTComponent
   | ASTSlot
+  | ASTSlotDefinition
   | ASTTCallBlock
   | ASTLog
   | ASTDebug
@@ -177,23 +200,35 @@ export type AST =
 // -----------------------------------------------------------------------------
 // Parser
 // -----------------------------------------------------------------------------
-interface ParsingContext {
+const cache: WeakMap<Element, AST> = new WeakMap();
-  inPreTag: boolean;
-  inSVG: boolean;
-}
 
-export function parse(xml: string | Node): AST {
+export function parse(xml: string | Element): AST {
-  const node = xml instanceof Element ? xml : (parseXML(`<t>${xml}</t>`).firstChild! as Element);
+  if (typeof xml === "string") {
-  normalizeXML(node);
+    const elem = parseXML(`<t>${xml}</t>`).firstChild as Element;
-  const ctx = { inPreTag: false, inSVG: false };
+    return _parse(elem);
-  const ast = parseNode(node, ctx);
+  }
+  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);
   }
@@ -208,6 +243,7 @@ function parseNode(node: ChildNode, ctx: ParsingContext): AST | null {
     parseTKey(node, ctx) ||
     parseTTranslation(node, ctx) ||
     parseTSlot(node, ctx) ||
+    parseTSetSlot(node, ctx) ||
     parseTOutNode(node, ctx) ||
     parseComponent(node, ctx) ||
     parseDOMNode(node, ctx) ||
@@ -233,7 +269,7 @@ 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 +317,8 @@ 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");
@@ -288,33 +326,37 @@ function parseDOMNode(node: Element, ctx: ParsingContext): AST | null {
   if (tagName === "t" && !dynamicTag) {
     return null;
   }
+  if (tagName.startsWith("block-")) {
+    throw new OwlError(`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"] = {};
+  let attrs: ASTDomNode["attrs"] = null;
-  const on: ASTDomNode["on"] = {};
+  let on: EventHandlers | null = null;
-  let model: ASTDomNode["model"] = null;
+  let model: TModelInfo | null = null;
 
   for (let attr of nodeAttrsNames) {
     const value = node.getAttribute(attr)!;
     if (attr.startsWith("t-on")) {
       if (attr === "t-on") {
-        throw new Error("Missing event name with t-on directive");
+        throw new OwlError("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)) {
-        throw new Error("The t-model directive only works with <input>, <textarea> and <select>");
+        throw new OwlError(
+          "The t-model directive only works with <input>, <textarea> and <select>"
+        );
       }
 
       let baseExpr, expr;
@@ -327,7 +369,7 @@ function parseDOMNode(node: Element, ctx: ParsingContext): AST | null {
         baseExpr = value.slice(0, index);
         expr = value.slice(index + 1, -1);
       } else {
-        throw new Error(`Invalid t-model expression: "${value}" (it should be assignable)`);
+        throw new OwlError(`Invalid t-model expression: "${value}" (it should be assignable)`);
       }
 
       const typeAttr = node.getAttribute("type");
@@ -348,16 +390,31 @@ 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) {
-      if (attr.startsWith("t-") && !attr.startsWith("t-att")) {
+        // don't pollute the original ctx
-        throw new Error(`Unknown QWeb directive: '${attr}'`);
+        ctx = Object.assign({}, ctx);
+        ctx.tModelInfo = model;
       }
+    } else if (attr.startsWith("block-")) {
+      throw new OwlError(`Invalid attribute: '${attr}'`);
+    } else if (attr !== "t-name") {
+      if (attr.startsWith("t-") && !attr.startsWith("t-att")) {
+        throw new OwlError(`Unknown QWeb directive: '${attr}'`);
+      }
+      const tModel = ctx.tModelInfo;
+      if (tModel && ["t-att-value", "t-attf-value"].includes(attr)) {
+        tModel.hasDynamicChildren = true;
+      }
+      attrs = attrs || {};
       attrs[attr] = value;
     }
   }
+
+  const children = parseChildren(node, ctx);
   return {
     type: ASTType.DomNode,
     tag: tagName,
@@ -400,7 +457,7 @@ function parseTEscNode(node: Element, ctx: ParsingContext): AST | null {
     };
   }
   if (ast.type === ASTType.TComponent) {
-    throw new Error("t-esc is not supported on Component nodes");
+    throw new OwlError("t-esc is not supported on Component nodes");
   }
   return tesc;
 }
@@ -456,7 +513,7 @@ function parseTForEach(node: Element, ctx: ParsingContext): AST | null {
   node.removeAttribute("t-as");
   const key = node.getAttribute("t-key");
   if (!key) {
-    throw new Error(
+    throw new OwlError(
       `"Directive t-foreach should always be used with a t-key!" (expression: t-foreach="${collection}" t-as="${elem}")`
     );
   }
@@ -511,21 +568,23 @@ function parseTCall(node: Element, ctx: ParsingContext): AST | null {
     return null;
   }
   const subTemplate = node.getAttribute("t-call")!;
-
+  const context = node.getAttribute("t-call-context");
   node.removeAttribute("t-call");
+  node.removeAttribute("t-call-context");
+
   if (node.tagName !== "t") {
     const ast = parseNode(node, ctx);
-    const tcall: AST = { type: ASTType.TCall, name: subTemplate, body: null };
+    const tcall: AST = { type: ASTType.TCall, name: subTemplate, body: null, context };
     if (ast && ast.type === ASTType.DomNode) {
       ast.content = [tcall];
       return ast;
     }
-    if (ast && ast.type === ASTType.TComponent) {
+    // if (ast && ast.type === ASTType.TComponent) {
-      return {
+    //   return {
-        ...ast,
+    //     ...ast,
-        slots: { default: { content: tcall } },
+    //     slots: { default: { content: tcall, scope: null, on: null, attrs: null } },
-      };
+    //   };
-    }
+    // }
   }
   const body = parseChildren(node, ctx);
 
@@ -533,6 +592,7 @@ function parseTCall(node: Element, ctx: ParsingContext): AST | null {
     type: ASTType.TCall,
     name: subTemplate,
     body: body.length ? body : null,
+    context,
   };
 }
 
@@ -619,7 +679,6 @@ 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.",
@@ -637,7 +696,9 @@ function parseComponent(node: Element, ctx: ParsingContext): AST | null {
   let isDynamic = node.hasAttribute("t-component");
 
   if (isDynamic && name !== "t") {
-    throw new Error(`Directive 't-component' can only be used on <t> nodes (used on a <${name}>)`);
+    throw new OwlError(
+      `Directive 't-component' can only be used on <t> nodes (used on a <${name}>)`
+    );
   }
 
   if (!(firstLetter === firstLetter.toUpperCase() || isDynamic)) {
@@ -651,74 +712,38 @@ 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("-"));
+      if (name.startsWith("t-on-")) {
-      throw new Error(message || `unsupported directive on Component: ${name}`);
+        on = on || {};
+        on[name.slice(5)] = value;
+      } else {
+        const message = directiveErrorMap.get(name.split("-").slice(0, 2).join("-"));
+        throw new OwlError(message || `unsupported directive on Component: ${name}`);
+      }
     } else {
+      props = props || {};
       props[name] = value;
     }
   }
 
-  const slots: ASTComponent["slots"] = {};
+  let body: ASTComponent["body"] = null;
+
+  // let slots: ASTComponent["slots"] | null = null;
   if (node.hasChildNodes()) {
-    const clone = <Element>node.cloneNode(true);
+    body = parseChildNodes(node, ctx);
-
+    if (!node.querySelector('[t-set-slot]')) {
-    // named slots
+      body = {type: ASTType.TSetSlot, name: "default", content: body, on: null, attrs: null, scope: null}
-    const slotNodes = Array.from(clone.querySelectorAll("[t-set-slot]"));
-    for (let slotNode of slotNodes) {
-      if (slotNode.tagName !== "t") {
-        throw new Error(
-          `Directive 't-set-slot' can only be used on <t> nodes (used on a <${slotNode.tagName}>)`
-        );
-      }
-      const name = slotNode.getAttribute("t-set-slot")!;
-
-      // check if this is defined in a sub component (in which case it should
-      // be ignored)
-      let el = slotNode.parentElement!;
-      let isInSubComponent = false;
-      while (el !== clone) {
-        if (el!.hasAttribute("t-component") || el!.tagName[0] === el!.tagName[0].toUpperCase()) {
-          isInSubComponent = true;
-          break;
-        }
-        el = el.parentElement!;
-      }
-      if (isInSubComponent) {
-        continue;
-      }
-
-      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;
-          }
-          attrs[attributeName] = value;
-        }
-        if (Object.keys(attrs).length) {
-          slotInfo.attrs = attrs;
-        }
-        slots[name] = slotInfo;
-      }
     }
 
-    // default slot
-    const defaultContent = parseChildNodes(clone, ctx);
-    if (defaultContent) {
-      slots.default = { content: defaultContent };
-    }
   }
-  return { type: ASTType.TComponent, name, isDynamic, dynamicProps, props, slots };
+  return { type: ASTType.TComponent, name, isDynamic, dynamicProps, props, body, on };
 }
 
 // -----------------------------------------------------------------------------
@@ -731,19 +756,92 @@ 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),
   };
 }
 
+function parseTSetSlot(node: Element, ctx: ParsingContext): AST | null {
+  if (!node.hasAttribute("t-set-slot")) {
+    return null;
+  }
+  // const t = el.ownerDocument.createElement("t");
+
+    // const clone = <Element>node.cloneNode(true);
+
+    // // named slots
+    // const slotNodes = Array.from(clone.querySelectorAll("[t-set-slot]"));
+    // for (let slotNode of slotNodes) {
+      if (node.tagName !== "t") {
+        throw new OwlError(
+          `Directive 't-set-slot' can only be used on <t> nodes (used on a <${node.tagName}>)`
+        );
+      }
+      const name = node.getAttribute("t-set-slot")!;
+
+    //   // check if this is defined in a sub component (in which case it should
+    //   // be ignored)
+    //   let el = slotNode.parentElement!;
+    //   let isInSubComponent = false;
+    //   while (el !== clone) {
+    //     if (el!.hasAttribute("t-component") || el!.tagName[0] === el!.tagName[0].toUpperCase()) {
+    //       isInSubComponent = true;
+    //       break;
+    //     }
+    //     el = el.parentElement!;
+    //   }
+    //   if (isInSubComponent) {
+    //     continue;
+    //   }
+
+      node.removeAttribute("t-set-slot");
+      node.remove();
+      const slotAst = parseNode(node, ctx);
+      let on: ASTSlotDefinition["on"] = null;
+      let attrs: Attrs | null = null;
+      let scope: string | null = null;
+      for (let attributeName of node.getAttributeNames()) {
+        const value = node.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;
+        }
+      }
+    //   slots = slots || {};
+      return { type: ASTType.TSetSlot, name, content: slotAst, on, attrs, scope };
+    // }
+
+    // // default slot
+    // const defaultContent = parseChildNodes(clone, ctx);
+    // slots = slots || {};
+    // // t-set-slot="default" has priority over content
+    // if (defaultContent && !slots.default) {
+    //   slots.default = { content: defaultContent, on, attrs: null, scope: defaultSlotScope };
+    // }
+}
+
 function parseTTranslation(node: Element, ctx: ParsingContext): AST | null {
   if (node.getAttribute("t-translation") !== "off") {
     return null;
@@ -786,7 +884,7 @@ 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 +903,7 @@ 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:
@@ -834,7 +932,7 @@ function normalizeTIf(el: Element) {
     let nattr = (name: string) => +!!node.getAttribute(name);
     if (prevElem && (pattr("t-if") || pattr("t-elif"))) {
       if (pattr("t-foreach")) {
-        throw new Error(
+        throw new OwlError(
           "t-if cannot stay at the same level as t-foreach when using t-elif or t-else"
         );
       }
@@ -843,19 +941,19 @@ function normalizeTIf(el: Element) {
           return a + b;
         }) > 1
       ) {
-        throw new Error("Only one conditional branching directive is allowed per node");
+        throw new OwlError("Only one conditional branching directive is allowed per node");
       }
       // All text (with only spaces) and comment nodes (nodeType 8) between
       // branch nodes are removed
       let textNode;
       while ((textNode = node.previousSibling) !== prevElem) {
         if (textNode!.nodeValue!.trim().length && textNode!.nodeType !== 8) {
-          throw new Error("text is not allowed between branching directives");
+          throw new OwlError("text is not allowed between branching directives");
         }
         textNode!.remove();
       }
     } else {
-      throw new Error(
+      throw new OwlError(
         "t-elif and t-else directives must be preceded by a t-if or t-elif directive"
       );
     }
@@ -876,7 +974,7 @@ function normalizeTEsc(el: Element) {
   );
   for (const el of elements) {
     if (el.childNodes.length) {
-      throw new Error("Cannot have t-esc on a component that already has content");
+      throw new OwlError("Cannot have t-esc on a component that already has content");
     }
     const value = el.getAttribute("t-esc");
     el.removeAttribute("t-esc");
@@ -930,7 +1028,7 @@ function parseXML(xml: string): XMLDocument {
         }
       }
     }
-    throw new Error(msg);
+    throw new OwlError(msg);
   }
 
   return doc;

src/component/lifecycle_hooks.ts

@@ -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));
-}

src/component/props_validation.ts

@@ -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;
-}

src/component/scheduler.ts

@@ -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();
-      }
-    });
-  }
-}

src/index.ts

@@ -1,62 +1,16 @@
-import { UTILS } from "./app/template_helpers";
+import { TemplateSet } from "./runtime/template_set";
-import {
+import { compile } from "./compiler";
-  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";
 
-config.shouldNormalizeDom = false;
+export * from "./runtime";
-config.mainEventHandler = mainEventHandler;
-(UTILS as any).Portal = Portal;
 
-export const blockDom = {
+TemplateSet.prototype._compileTemplate = function _compileTemplate(
-  config,
+  name: string,
-  // bdom entry points
+  template: string | Element
-  mount: blockMount,
+) {
-  patch,
+  return compile(template, {
-  remove,
+    name,
-  // bdom block types
+    dev: this.dev,
-  list,
+    translateFn: this.translateFn,
-  multi,
+    translatableAttributes: this.translatableAttributes,
-  text,
+  });
-  toggler,
-  createBlock,
-  html,
-  comment,
 };
-
-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 { reactive } from "./reactivity";
-export { useState } from "./component/component_node";
-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__ = {};

src/memo.ts

@@ -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;
-}

src/portal.ts

@@ -1,75 +0,0 @@
-import { onWillUnmount } from "./component/lifecycle_hooks";
-import { xml } from "./app/template_set";
-import { BDom, text, VNode } from "./blockdom";
-import { Component } from "./component/component";
-
-const VText: any = text("").constructor;
-
-class VPortal extends VText implements Partial<VNode<VPortal>> {
-  //   selector: string;
-  realBDom: BDom | null;
-  target: HTMLElement | null = null;
-
-  constructor(selector: string, realBDom: BDom) {
-    super("");
-    this.selector = selector;
-    this.realBDom = realBDom;
-  }
-  mount(parent: HTMLElement, anchor: ChildNode) {
-    super.mount(parent, anchor);
-    this.target = document.querySelector(this.selector) as any;
-    if (!this.target) {
-      let el: any = this.el;
-      while (el && el.parentElement instanceof HTMLElement) {
-        el = el.parentElement;
-      }
-      this.target = el && el.querySelector(this.selector);
-      if (!this.target) {
-        throw new Error("invalid portal target");
-      }
-    }
-    this.realBDom!.mount(this.target!, null);
-  }
-
-  beforeRemove() {
-    this.realBDom!.beforeRemove();
-  }
-  remove() {
-    if (this.realBDom) {
-      super.remove();
-      this.realBDom!.remove();
-      this.realBDom = null;
-    }
-  }
-
-  patch(other: VPortal) {
-    super.patch(other);
-    if (this.realBDom) {
-      this.realBDom.patch(other.realBDom!, true);
-    } else {
-      this.realBDom = other.realBDom;
-      this.realBDom!.mount(this.target!, null);
-    }
-  }
-}
-
-export class Portal extends Component {
-  static template = xml`<t t-slot="default"/>`;
-  static props = {
-    target: {
-      type: String,
-    },
-    slots: true,
-  };
-
-  setup() {
-    const node = this.__owl__;
-    const renderFn = node.renderFn;
-    node.renderFn = () => new VPortal(this.props.target, renderFn());
-    onWillUnmount(() => {
-      if (node.bdom) {
-        node.bdom.remove();
-      }
-    });
-  }
-}

src/reactivity.ts

@@ -1,190 +0,0 @@
-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");
-// 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
- */
-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();
-}
-
-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>;
-}

src/runtime/app.ts

@@ -0,0 +1,210 @@
+import { Component, ComponentConstructor, Props } from "./component";
+import { ComponentNode } from "./component_node";
+import { nodeErrorHandlers, OwlError, handleError } from "./error_handling";
+import { Fiber, RootFiber, MountOptions } from "./fibers";
+import { Scheduler } from "./scheduler";
+import { validateProps } from "./template_helpers";
+import { TemplateSet, TemplateSetConfig } from "./template_set";
+import { validateTarget } from "./utils";
+
+// 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.`;
+};
+
+declare global {
+  interface Window {
+    __OWL_DEVTOOLS__: {
+      apps: Set<App>;
+      Fiber: typeof Fiber;
+      RootFiber: typeof RootFiber;
+    };
+  }
+}
+
+window.__OWL_DEVTOOLS__ ||= {
+  apps: new Set<App>(),
+  Fiber: Fiber,
+  RootFiber: RootFiber,
+};
+
+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;
+    window.__OWL_DEVTOOLS__.apps.add(this);
+    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) {
+          reject(e);
+        }
+        throw e;
+      });
+    });
+    node.mountComponent(target, options);
+    return promise;
+  }
+
+  destroy() {
+    if (this.root) {
+      this.scheduler.flush();
+      this.root.destroy();
+    }
+    window.__OWL_DEVTOOLS__.apps.delete(this);
+  }
+
+  createComponent<P extends Props>(
+    name: string | null,
+    isStatic: boolean,
+    hasSlotsProp: boolean,
+    hasDynamicPropList: boolean,
+    hasNoProp: boolean
+  ) {
+    const isDynamic = !isStatic;
+    function _arePropsDifferent(props1: Props, props2: Props): boolean {
+      for (let k in props1) {
+        if (props1[k] !== props2[k]) {
+          return true;
+        }
+      }
+      return hasDynamicPropList && Object.keys(props1).length !== Object.keys(props2).length;
+    }
+    const arePropsDifferent = hasSlotsProp
+      ? (_1: any, _2: any) => true
+      : hasNoProp
+      ? (_1: any, _2: any) => false
+      : _arePropsDifferent;
+    const updateAndRender = ComponentNode.prototype.updateAndRender;
+    const initiateRender = ComponentNode.prototype.initiateRender;
+
+    return (props: P, key: string, ctx: ComponentNode, parent: any, C: any) => {
+      let children = ctx.children;
+      let node: any = children[key];
+      if (isDynamic && node && node.component.constructor !== C) {
+        node = undefined;
+      }
+      const parentFiber = ctx.fiber!;
+      if (node) {
+        if (arePropsDifferent(node.props, props) || parentFiber.deep || node.forceNextRender) {
+          node.forceNextRender = false;
+          updateAndRender.call(node, props, parentFiber);
+        }
+      } else {
+        // new component
+        if (isStatic) {
+          const components = parent.constructor.components;
+          if (!components) {
+            throw new OwlError(
+              `Cannot find the definition of component "${name}", missing static components key in parent`
+            );
+          }
+          C = components[name as any];
+          if (!C) {
+            throw new OwlError(`Cannot find the definition of component "${name}"`);
+          } else if (!(C.prototype instanceof Component)) {
+            throw new OwlError(
+              `"${name}" is not a Component. It must inherit from the Component class`
+            );
+          }
+        }
+        node = new ComponentNode(C, props, this, ctx, key);
+        children[key] = node;
+        initiateRender.call(node, new Fiber(node, parentFiber));
+      }
+      parentFiber.childrenMap[key] = node;
+      return node;
+    };
+  }
+
+  handleError(...args: Parameters<typeof handleError>) {
+    return handleError(...args);
+  }
+}
+
+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);
+}

src/runtime/blockdom/attributes.ts

@@ -93,6 +93,10 @@ function toClassObj(expr: string | number | { [c: string]: any }) {
       for (let key in expr as any) {
         const value = (expr as any)[key];
         if (value) {
+          key = trim.call(key);
+          if (!key) {
+            continue;
+          }
           const words = split.call(key, wordRegexp);
           for (let word of words) {
             result[word] = value;
@@ -139,7 +143,8 @@ 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 ? value.valueOf() : "";
   };
 }
 

src/runtime/blockdom/block_compiler.ts

@@ -1,3 +1,4 @@
+import { OwlError } from "../error_handling";
 import {
   attrsSetter,
   attrsUpdater,
@@ -156,6 +157,15 @@ function buildTree(
           : document.createElement(tagName);
       }
       if (el instanceof Element) {
+        if (!domParentTree) {
+          // some html elements may have side effects when setting their attributes.
+          // For example, setting the src attribute of an <img/> will trigger a
+          // request to get the corresponding image. This is something that we
+          // don't want at compile time. We avoid that by putting the content of
+          // the block in a <template/> element
+          const fragment = document.createElement("template").content;
+          fragment.appendChild(el);
+        }
         for (let i = 0; i < attrs.length; i++) {
           const attrName = attrs[i].name;
           const attrValue = attrs[i].value;
@@ -245,7 +255,7 @@ function buildTree(
       };
     }
   }
-  throw new Error("boom");
+  throw new OwlError("boom");
 }
 
 function addRef(tree: IntermediateTree) {
@@ -299,12 +309,13 @@ 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 +419,11 @@ 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 +437,21 @@ 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) {
+        for (let cbRef of cbRefs) {
-          let fn = (this as any).data[ref];
+          let fn = (this as any).data[cbRef];
           fn(null);
         }
       }
@@ -476,12 +496,12 @@ 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;
@@ -497,51 +517,71 @@ function createBlockClass(template: HTMLElement, ctx: BlockCtx): BlockClass {
       return this.el!;
     }
 
-    moveBefore(other: Block | null, afterNode: Node | null) {
+    moveBeforeDOMNode(node: Node | null, parent = this.parentEl) {
-      const target = other ? other.el! : afterNode;
+      this.parentEl = parent;
-      nodeInsertBefore.call(this.parentEl, this.el!, target);
+      nodeInsertBefore.call(parent, this.el!, node);
+    }
+
+    moveBeforeVNode(other: Block | null, afterNode: Node | null) {
+      nodeInsertBefore.call(this.parentEl, this.el!, other ? other.el! : afterNode);
+    }
+
+    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) {
+      this.el = el;
-        // collecting references
+      this.parentEl = parent;
-        const refs: Node[] = new Array(refN);
+    }
-        this.refs = refs;
+    patch(other: Block, withBeforeRemove: boolean) {}
-        refs[0] = el;
+  }
-        for (let i = 0; i < colN; i++) {
-          const w = collectors[i];
-          refs[w.idx] = w.getVal.call(refs[w.prevIdx]);
-        }
 
-        // applying data to all update points
+  if (isDynamic) {
-        if (locN) {
+    Block.prototype.mount = function mount(parent: HTMLElement, afterNode: Node | null) {
-          const data = this.data!;
+      const el = nodeCloneNode.call(template, true);
-          for (let i = 0; i < locN; i++) {
+      // collecting references
-            const loc = locations[i];
+      const refs: Node[] = new Array(refN);
-            loc.setData.call(refs[loc.refIdx], data[i]);
+      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
+      // applying data to all update points
-        if (childN) {
+      if (locN) {
-          const children = this.children;
+        const data = this.data!;
-          for (let i = 0; i < childN; i++) {
+        for (let i = 0; i < locN; i++) {
-            const child = children![i];
+          const loc = locations[i];
-            if (child) {
+          loc.setData.call(refs[loc.refIdx], data[i]);
-              const loc = childrenLocs[i];
+        }
-              const afterNode = loc.afterRefIdx ? refs[loc.afterRefIdx] : null;
+      }
-              child.isOnlyChild = loc.isOnlyChild;
+
-              child.mount(refs[loc.parentRefIdx] as any, afterNode);
+      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 +626,17 @@ function createBlockClass(template: HTMLElement, ctx: BlockCtx): BlockClass {
           }
         }
       }
-    }
+    };
-    toString() {
+  }
-      const div = document.createElement("div");
+  return Block;
-      this.mount(div, null);
-      return div.innerHTML;
-    }
-  };
 }
 
 function setText(this: Text, value: any) {
   characterDataSetData.call(this, toText(value));
 }
 
-function setRef(this: HTMLElement, fn: any) {
+function makeRefSetter(index: number, refs: (() => void)[][]): Setter<HTMLElement> {
-  fn(this);
+  return function setRef(this: HTMLElement, fn: any) {
+    refs[refs.length - 1][index] = () => fn(this);
+  };
 }

src/runtime/blockdom/event_catcher.ts

@@ -0,0 +1,111 @@
+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 && currentNode !== afterNode) {
+            if (currentNode.contains(target)) {
+              return origFn.call(this, ev);
+            }
+            currentNode = currentNode.nextSibling;
+          }
+        };
+      }
+    }
+
+    moveBeforeDOMNode(node: Node | null, parent = this.parentEl) {
+      this.parentEl = parent;
+      this.child.moveBeforeDOMNode(node, parent);
+      parent!.insertBefore(this.afterNode!, node);
+    }
+
+    moveBeforeVNode(other: VCatcher | null, afterNode: Node | null) {
+      if (other) {
+        // check this with @ged-odoo for use in foreach
+        afterNode = other.firstNode() || afterNode;
+      }
+      this.child.moveBeforeVNode(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);
+  };
+}

src/runtime/blockdom/events.ts

@@ -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 {
@@ -26,8 +27,8 @@ function createElementHandler(evName: string, capture: boolean = false): EventHa
   }
 
   function listener(ev: Event) {
-    const currentTarget = ev.currentTarget;
+    const currentTarget = ev.currentTarget as HTMLElement;
-    if (!currentTarget || !document.contains(currentTarget as HTMLElement)) return;
+    if (!currentTarget || !currentTarget.ownerDocument.contains(currentTarget)) return;
     const data = (currentTarget as any)[eventKey];
     if (!data) return;
     config.mainEventHandler(data, ev, currentTarget);
@@ -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) {

src/runtime/blockdom/html.ts

@@ -29,14 +29,18 @@ class VHtml {
     }
   }
 
-  moveBefore(other: VHtml | null, afterNode: Node | null) {
+  moveBeforeDOMNode(node: Node | null, parent = this.parentEl) {
-    const target = other ? other.content[0] : afterNode;
+    this.parentEl = parent;
-    const parent = this.parentEl;
     for (let elem of this.content) {
-      nodeInsertBefore.call(parent, elem, target);
+      nodeInsertBefore.call(parent, elem, node);
     }
   }
 
+  moveBeforeVNode(other: VHtml | null, afterNode: Node | null) {
+    const target = other ? other.content[0] : afterNode;
+    this.moveBeforeDOMNode(target);
+  }
+
   patch(other: VHtml) {
     if (this === other) {
       return;
@@ -61,6 +65,7 @@ class VHtml {
       // remove current content
       this.remove();
       this.content = content;
+      this.html = other.html;
     }
   }
 

src/runtime/blockdom/index.ts

@@ -6,10 +6,12 @@ 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;
-  moveBefore(other: T | null, afterNode: Node | null): void;
+  moveBeforeDOMNode(node: Node | null, parent?: HTMLElement): void;
+  moveBeforeVNode(other: T | null, afterNode: Node | null): void;
   patch(other: T, withBeforeRemove: boolean): void;
   beforeRemove(): void;
   remove(): void;

src/runtime/blockdom/list.ts

@@ -38,14 +38,23 @@ class VList {
     this.parentEl = parent;
   }
 
-  moveBefore(other: VList | null, afterNode: Node | null) {
+  moveBeforeDOMNode(node: Node | null, parent = this.parentEl) {
+    this.parentEl = parent;
+    const children = this.children;
+    for (let i = 0, l = children.length; i < l; i++) {
+      children[i].moveBeforeDOMNode(node, parent);
+    }
+    parent!.insertBefore(this.anchor!, node);
+  }
+
+  moveBeforeVNode(other: VList | null, afterNode: Node | null) {
     if (other) {
       const next = other!.children[0];
       afterNode = (next ? next.firstNode() : other!.anchor) || null;
     }
     const children = this.children;
     for (let i = 0, l = children.length; i < l; i++) {
-      children[i].moveBefore(null, afterNode);
+      children[i].moveBeforeVNode(null, afterNode);
     }
     this.parentEl!.insertBefore(this.anchor!, afterNode);
   }
@@ -66,7 +75,7 @@ class VList {
       patch: cPatch,
       remove: cRemove,
       beforeRemove,
-      moveBefore: cMoveBefore,
+      moveBeforeVNode: cMoveBefore,
       firstNode: cFirstNode,
     } = proto;
 

src/runtime/blockdom/multi.ts

@@ -38,7 +38,22 @@ export class VMulti {
     this.parentEl = parent;
   }
 
-  moveBefore(other: VMulti | null, afterNode: Node | null) {
+  moveBeforeDOMNode(node: Node | null, parent = this.parentEl) {
+    this.parentEl = parent;
+    const children = this.children;
+    const anchors = this.anchors;
+    for (let i = 0, l = children.length; i < l; i++) {
+      let child = children[i];
+      if (child) {
+        child.moveBeforeDOMNode(node, parent);
+      } else {
+        const anchor = anchors![i];
+        nodeInsertBefore.call(parent, anchor, node);
+      }
+    }
+  }
+
+  moveBeforeVNode(other: VMulti | null, afterNode: Node | null) {
     if (other) {
       const next = other!.children[0];
       afterNode = (next ? next.firstNode() : other!.anchors![0]) || null;
@@ -49,7 +64,7 @@ export class VMulti {
     for (let i = 0, l = children.length; i < l; i++) {
       let child = children[i];
       if (child) {
-        child.moveBefore(null, afterNode);
+        child.moveBeforeVNode(null, afterNode);
       } else {
         const anchor = anchors![i];
         nodeInsertBefore.call(parent, anchor, afterNode);

src/runtime/blockdom/text.ts

@@ -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;
   }
 
@@ -23,9 +23,13 @@ abstract class VSimpleNode {
     this.el = node;
   }
 
-  moveBefore(other: VText | null, afterNode: Node | null) {
+  moveBeforeDOMNode(node: Node | null, parent = this.parentEl) {
-    const target = other ? other.el! : afterNode;
+    this.parentEl = parent;
-    nodeInsertBefore.call(this.parentEl, this.el!, target);
+    nodeInsertBefore.call(parent, this.el!, node);
+  }
+
+  moveBeforeVNode(other: VText | null, afterNode: Node | null) {
+    nodeInsertBefore.call(this.parentEl, this.el!, other ? other.el! : afterNode);
   }
 
   beforeRemove() {}
@@ -65,7 +69,7 @@ class VComment extends VSimpleNode {
   patch() {}
 }
 
-export function text(str: string): VNode<VText> {
+export function text(str: string | String): VNode<VText> {
   return new VText(str);
 }
 

src/runtime/blockdom/toggler.ts

@@ -20,8 +20,12 @@ class VToggler {
     this.child.mount(parent, afterNode);
   }
 
-  moveBefore(other: VToggler | null, afterNode: Node | null) {
+  moveBeforeDOMNode(node: Node | null, parent?: HTMLElement) {
-    this.child.moveBefore(other ? other.child : null, afterNode);
+    this.child.moveBeforeDOMNode(node, parent);
+  }
+
+  moveBeforeVNode(other: VToggler | null, afterNode: Node | null) {
+    this.moveBeforeDOMNode((other && other.firstNode()) || afterNode);
   }
 
   patch(other: VToggler, withBeforeRemove: boolean) {

src/runtime/component.ts

@@ -1,12 +1,30 @@
+import { Schema } from "./validation";
 import type { ComponentNode } from "./component_node";
 
 // -----------------------------------------------------------------------------
 //  Component Class
 // -----------------------------------------------------------------------------
 
+export 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(force: boolean = false) {
+  render(deep: boolean = false) {
-    this.__owl__.render(force);
+    this.__owl__.render(deep === true);
   }
 }

src/runtime/component_node.ts

@@ -1,23 +1,18 @@
-import type { App, Env } from "../app/app";
+import type { App, Env } from "./app";
-import { BDom, VNode } from "../blockdom";
+import { BDom, VNode } from "./blockdom";
-import { clearReactivesForCallback, Reactive, reactive, TARGET } from "../reactivity";
+import { Component, ComponentConstructor, Props } from "./component";
-import { batched, Callback } from "../utils";
+import { fibersInError, OwlError } from "./error_handling";
-import { Component } from "./component";
+import { Fiber, makeChildFiber, makeRootFiber, MountFiber, MountOptions } from "./fibers";
-import { fibersInError, handleError } from "./error_handling";
+import { clearReactivesForCallback, getSubscriptions, reactive, targets } from "./reactivity";
-import {
-  Fiber,
-  makeChildFiber,
-  makeRootFiber,
-  MountFiber,
-  MountOptions,
-  RootFiber,
-} from "./fibers";
-import { applyDefaultProps } from "./props_validation";
 import { STATUS } from "./status";
+import { batched, Callback } from "./utils";
 
 let currentNode: ComponentNode | null = null;
 
-export function getCurrent(): ComponentNode | null {
+export function getCurrent(): ComponentNode {
+  if (!currentNode) {
+    throw new OwlError("No active component (a hook function should only be called in 'setup')");
+  }
   return currentNode;
 }
 
@@ -25,6 +20,16 @@ export function useComponent(): Component {
   return currentNode!.component;
 }
 
+/**
+ * Apply default props (only top level).
+ */
+function applyDefaultProps<P extends object>(props: P, defaultProps: Partial<P>) {
+  for (let propName in defaultProps) {
+    if (props[propName] === undefined) {
+      (props as any)[propName] = defaultProps[propName];
+    }
+  }
+}
 // -----------------------------------------------------------------------------
 // Integration with reactivity system (useState)
 // -----------------------------------------------------------------------------
@@ -40,98 +45,37 @@ const batchedRenderFunctions = new WeakMap<ComponentNode, Callback>();
  *  relevant changes
  * @see reactive
  */
-export function useState<T extends object>(state: T): Reactive<T> {
+export function useState<T extends object>(state: T): T {
-  const node = currentNode!;
+  const node = getCurrent();
   let render = batchedRenderFunctions.get(node)!;
   if (!render) {
-    render = batched(node.render.bind(node));
+    render = batched(node.render.bind(node, false));
     batchedRenderFunctions.set(node, render);
-    // manual implementation of onWillUnmount to break cyclic dependency
+    // manual implementation of onWillDestroy to break cyclic dependency
-    node.willUnmount.unshift(clearReactivesForCallback.bind(null, render));
+    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) {
-    if (props1[k] !== props2[k]) {
-      return true;
-    }
-  }
-  return false;
-}
-export function component(
-  name: string | typeof Component,
-  props: any,
-  key: string,
-  ctx: ComponentNode,
-  parent: any
-): ComponentNode {
-  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 (isDynamic && node && node.component.constructor !== name) {
-    node = undefined;
-  }
-
-  const parentFiber = ctx.fiber!;
-  if (node) {
-    const currentProps = node.component.props[TARGET];
-    if (parentFiber.force || arePropsDifferent(currentProps, props)) {
-      node.updateAndRender(props, parentFiber);
-    }
-  } else {
-    // new component
-    let C;
-    if (isDynamic) {
-      C = name;
-    } else {
-      C = parent.constructor.components[name as any];
-      if (!C) {
-        throw new Error(`Cannot find the definition of component "${name}"`);
-      }
-    }
-    node = new ComponentNode(C, props, ctx.app, ctx);
-    ctx.children[key] = node;
-
-    const fiber = makeChildFiber(node, parentFiber);
-    node.initiateRender(fiber);
-  }
-  return node;
-}
-
 // -----------------------------------------------------------------------------
 //  Component VNode class
 // -----------------------------------------------------------------------------
 
 type LifecycleHook = Function;
 
-export class ComponentNode<T extends typeof Component = typeof Component>
+export class ComponentNode<P extends Props = any, E = any> implements VNode<ComponentNode<P, E>> {
-  implements VNode<ComponentNode>
-{
   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;
-  level: number;
   childEnv: Env;
   children: { [key: string]: ComponentNode } = Object.create(null);
   refs: any = {};
@@ -144,18 +88,36 @@ 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.level = parent ? parent.level + 1 : 0;
+    this.props = props;
-    applyDefaultProps(props, C);
+    this.parentKey = parentKey;
+    const defaultProps = C.defaultProps;
+    props = Object.assign({}, props);
+    if (defaultProps) {
+      applyDefaultProps(props, defaultProps);
+    }
     const env = (parent && parent.childEnv) || app.env;
     this.childEnv = env;
-    props = useState(props);
+    for (const key in props) {
-    this.component = new C(props, env, this) as any;
+      const prop = props[key];
-    this.renderFn = app.getTemplate(C.template).bind(this.component, this.component, this);
+      if (prop && typeof prop === "object" && targets.has(prop)) {
+        props[key] = useState(prop);
+      }
+    }
+    this.component = new C(props, env, this);
+    const ctx = Object.assign(Object.create(this.component), { this: this.component });
+    this.renderFn = app.getTemplate(C.template).bind(this.component, ctx, this);
     this.component.setup();
+    currentNode = null;
   }
 
   mountComponent(target: any, options?: MountOptions) {
@@ -173,32 +135,39 @@ export class ComponentNode<T extends typeof Component = typeof Component>
     try {
       await Promise.all(this.willStart.map((f) => f.call(component)));
     } catch (e) {
-      handleError({ node: this, error: e });
+      this.app.handleError({ node: this, error: e });
       return;
     }
     if (this.status === STATUS.NEW && this.fiber === fiber) {
-      this._render(fiber);
+      fiber.render();
     }
   }
 
-  async render(force: boolean = false) {
+  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)) {
+    if (current) {
-      if (current.force || force === false) {
+      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
-    if (!this.bdom && !current) {
+      deep = deep || current.deep;
+    } else if (!this.bdom) {
       return;
     }
 
-    const fiber = makeRootFiber(this, force);
+    const fiber = makeRootFiber(this);
+    fiber.deep = deep;
     this.fiber = fiber;
+
     this.app.scheduler.addFiber(fiber);
     await Promise.resolve();
     if (this.status === STATUS.DESTROYED) {
@@ -216,16 +185,7 @@ 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);
+      fiber.render();
-    }
-  }
-
-  _render(fiber: Fiber | RootFiber) {
-    try {
-      fiber.bdom = this.renderFn();
-      fiber.root!.counter--;
-    } catch (e) {
-      handleError({ node: this, error: e });
     }
   }
 
@@ -247,28 +207,46 @@ 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) {
+    if (this.willDestroy.length) {
-      cb.call(component);
+      try {
+        for (let cb of this.willDestroy) {
+          cb.call(component);
+        }
+      } catch (e) {
+        this.app.handleError({ error: e, node: this });
+      }
     }
     this.status = STATUS.DESTROYED;
   }
 
-  async updateAndRender(props: any, parentFiber: Fiber) {
+  async updateAndRender(props: P, parentFiber: Fiber) {
+    const rawProps = props;
+    props = Object.assign({}, 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) {
+      applyDefaultProps(props, defaultProps);
+    }
 
     currentNode = this;
-    props = useState(props);
+    for (const key in props) {
+      const prop = props[key];
+      if (prop && typeof prop === "object" && targets.has(prop)) {
+        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);
@@ -318,11 +296,16 @@ 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;
   }
 
-  moveBefore(other: ComponentNode | null, afterNode: Node | null) {
+  moveBeforeDOMNode(node: Node | null, parent?: HTMLElement): void {
-    this.bdom!.moveBefore(other ? other.bdom : null, afterNode);
+    this.bdom!.moveBeforeDOMNode(node, parent);
+  }
+
+  moveBeforeVNode(other: ComponentNode<P, E> | null, afterNode: Node | null) {
+    this.bdom!.moveBeforeVNode(other ? other.bdom : null, afterNode);
   }
 
   patch() {
@@ -334,12 +317,16 @@ export class ComponentNode<T extends typeof Component = typeof Component>
     }
   }
   _patch() {
-    const hasChildren = Object.keys(this.children).length > 0;
+    let hasChildren = false;
-    this.bdom!.patch(this!.fiber!.bdom!, hasChildren);
+    // eslint-disable-next-line @typescript-eslint/no-unused-vars
-    if (hasChildren) {
+    for (let _k in this.children) {
-      this.cleanOutdatedChildren();
+      hasChildren = true;
+      break;
     }
-    this.fiber!.appliedToDom = true;
+    const fiber = this.fiber!;
+    this.children = fiber.childrenMap;
+    this.bdom!.patch(fiber.bdom!, hasChildren);
+    fiber.appliedToDom = true;
     this.fiber = null;
   }
 
@@ -351,17 +338,15 @@ export class ComponentNode<T extends typeof Component = typeof Component>
     this.bdom!.remove();
   }
 
-  cleanOutdatedChildren() {
+  // ---------------------------------------------------------------------------
-    const children = this.children;
+  // Some debug helpers
-    for (const key in children) {
+  // ---------------------------------------------------------------------------
-      const node = children[key];
+  get name(): string {
-      const status = node.status;
+    return this.component.constructor.name;
-      if (status !== STATUS.MOUNTED) {
+  }
-        delete children[key];
+
-        if (status !== STATUS.DESTROYED) {
+  get subscriptions(): ReturnType<typeof getSubscriptions> {
-          node.destroy();
+    const render = batchedRenderFunctions.get(this);
-        }
+    return render ? getSubscriptions(render) : [];
-      }
-    }
   }
 }

src/runtime/error_handling.ts

@@ -1,11 +1,16 @@
 import type { ComponentNode } from "./component_node";
 import type { Fiber } from "./fibers";
 
+// Custom error class that wraps error that happen in the owl lifecycle
+export class OwlError extends Error {
+  cause?: any;
+}
+
 // Maps fibers to thrown errors
 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 +21,19 @@ 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 (handled) {
-      if (isFirstRound && fiber && fiber.node.fiber) {
-        fiber.root!.counter--;
-      }
       return true;
     }
   }
@@ -40,7 +42,14 @@ function _handleError(node: ComponentNode | null, error: any, isFirstRound = fal
 
 type ErrorParams = { error: any } & ({ node: ComponentNode } | { fiber: Fiber });
 export function handleError(params: ErrorParams) {
-  const error = params.error;
+  let { error } = params;
+  // Wrap error if it wasn't wrapped by wrapError (ie when not in dev mode)
+  if (!(error instanceof OwlError)) {
+    error = Object.assign(
+      new OwlError(`An error occured in the owl lifecycle (see this Error's "cause" property)`),
+      { cause: error }
+    );
+  }
   const node = "node" in params ? params.node : params.fiber.node;
   const fiber = "fiber" in params ? params.fiber : node.fiber!;
 
@@ -54,7 +63,7 @@ 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 {
@@ -62,5 +71,6 @@ export function handleError(params: ErrorParams) {
     } catch (e) {
       console.error(e);
     }
+    throw error;
   }
 }

src/runtime/event_handling.ts

@@ -1,5 +1,6 @@
-import { filterOutModifiersFromData } from "../blockdom/config";
+import { filterOutModifiersFromData } from "./blockdom/config";
 import { STATUS } from "./status";
+import { OwlError } from "./error_handling";
 
 export const mainEventHandler = (data: any, ev: Event, currentTarget?: EventTarget | null) => {
   const { data: _data, modifiers } = filterOutModifiersFromData(data);
@@ -33,7 +34,7 @@ export const mainEventHandler = (data: any, ev: Event, currentTarget?: EventTarg
   if (Object.hasOwnProperty.call(data, 0)) {
     const handler = data[0];
     if (typeof handler !== "function") {
-      throw new Error(`Invalid handler (expected a function, received: '${handler}')`);
+      throw new OwlError(`Invalid handler (expected a function, received: '${handler}')`);
     }
     let node = data[1] ? data[1].__owl__ : null;
     if (node ? node.status === STATUS.MOUNTED : true) {

src/runtime/fibers.ts

@@ -1,27 +1,30 @@
-import { BDom, mount } from "../blockdom";
+import { BDom, mount } from "./blockdom";
 import type { ComponentNode } from "./component_node";
-import { fibersInError, handleError } from "./error_handling";
+import { fibersInError, OwlError } from "./error_handling";
 import { STATUS } from "./status";
 
 export function makeChildFiber(node: ComponentNode, parent: Fiber): Fiber {
   let current = node.fiber;
   if (current) {
-    let root = parent.root;
+    cancelFibers(current.children);
-    cancelFibers(root, current.children);
     current.root = null;
   }
   return new Fiber(node, parent);
 }
 
-export function makeRootFiber(node: ComponentNode, force: boolean): Fiber {
+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;
-    current.force = force;
     if (fibersInError.has(current)) {
       fibersInError.delete(current);
       fibersInError.delete(root);
@@ -36,22 +39,38 @@ export function makeRootFiber(node: ComponentNode, force: boolean): Fiber {
   if (node.patched.length) {
     fiber.patched.push(fiber);
   }
-  fiber.force = force;
   return fiber;
 }
 
+function throwOnRender() {
+  throw new OwlError("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;
+    let node = fiber.node;
-    fiber.root = root;
+    fiber.render = throwOnRender;
-    if (!fiber.bdom) {
+    if (node.status === STATUS.NEW) {
+      node.destroy();
+      delete node.parent!.children[node.parentKey!];
+    }
+    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;
 }
@@ -63,21 +82,59 @@ export class Fiber {
   parent: Fiber | null;
   children: Fiber[] = [];
   appliedToDom = false;
-  force: boolean = false;
+  deep: boolean = false;
+  childrenMap: ComponentNode["children"] = {};
 
   constructor(node: ComponentNode, parent: Fiber | null) {
     this.node = node;
     this.parent = parent;
     if (parent) {
-      this.force = parent.force;
+      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) {
+        node.app.handleError({ node, error: e });
+      }
+      root.setCounter(root.counter - 1);
+    }
+  }
 }
 
 export class RootFiber extends Fiber {
@@ -138,7 +195,14 @@ export class RootFiber extends Fiber {
       }
     } catch (e) {
       this.locked = false;
-      handleError({ fiber: current || this, error: e });
+      node.app.handleError({ fiber: current || this, error: e });
+    }
+  }
+
+  setCounter(newValue: number) {
+    this.counter = newValue;
+    if (newValue === 0) {
+      this.node.app.scheduler.flush();
     }
   }
 }
@@ -162,6 +226,8 @@ 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,
@@ -193,7 +259,7 @@ export class MountFiber extends RootFiber {
         }
       }
     } catch (e) {
-      handleError({ fiber: current as Fiber, error: e });
+      this.node.app.handleError({ fiber: current as Fiber, error: e });
     }
   }
 }

src/runtime/hooks.ts

@@ -1,6 +1,6 @@
-import type { Env } from "./app/app";
+import type { Env } from "./app";
-import { getCurrent } from "./component/component_node";
+import { getCurrent } from "./component_node";
-import { onMounted, onPatched, onWillUnmount } from "./component/lifecycle_hooks";
+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 node = getCurrent();
-  const env = Object.create(node.childEnv);
+  node.component.env = extendEnv(node.component.env as any, envExtension);
-  const descrs = Object.getOwnPropertyDescriptors(envExtension);
+  useChildSubEnv(envExtension);
-  node.childEnv = Object.freeze(Object.defineProperties(env, descrs));
 }
 
+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();
+      if (cleanup) {
-      cleanup = effect(...dependencies) || NO_OP;
+        cleanup();
+      }
+      cleanup = effect(...dependencies);
     }
   });
 
-  onWillUnmount(() => cleanup());
+  onWillUnmount(() => cleanup && cleanup());
 }
 
 // -----------------------------------------------------------------------------
@@ -107,12 +117,12 @@ export function useEffect(effect: Effect, computeDependencies: () => any[] = ()
  *  `useExternalListener(window, 'click', this._doSomething);`
  * */
 export function useExternalListener(
-  target: HTMLElement | typeof window,
+  target: EventTarget,
   eventName: string,
   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));

src/runtime/index.ts

@@ -0,0 +1,59 @@
+import {
+  config,
+  createBlock,
+  html,
+  list,
+  mount as blockMount,
+  multi,
+  patch,
+  remove,
+  text,
+  toggler,
+  comment,
+} from "./blockdom";
+import { mainEventHandler } from "./event_handling";
+
+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 type { ComponentConstructor } 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 { OwlError } from "./error_handling";
+
+export const __info__ = {};

src/runtime/lifecycle_hooks.ts

@@ -0,0 +1,122 @@
+import { getCurrent } from "./component_node";
+import { nodeErrorHandlers, OwlError } from "./error_handling";
+
+const TIMEOUT = Symbol("timeout");
+function wrapError(fn: (...args: any[]) => any, hookName: string) {
+  const error = new OwlError(`The following error occurred in ${hookName}: `) as Error & {
+    cause: any;
+  };
+  const timeoutError = new OwlError(`${hookName}'s promise hasn't resolved after 3 seconds`);
+  const node = getCurrent();
+  return (...args: any[]) => {
+    const onError = (cause: any) => {
+      error.cause = cause;
+      if (cause instanceof Error) {
+        error.message += `"${cause.message}"`;
+      } else {
+        error.message = `Something that is not an Error was thrown in ${hookName} (see this Error's "cause" property)`;
+      }
+      throw error;
+    };
+    try {
+      const result = fn(...args);
+      if (result instanceof Promise) {
+        if (hookName === "onWillStart" || hookName === "onWillUpdateProps") {
+          const fiber = node.fiber;
+          Promise.race([
+            result.catch(() => {}),
+            new Promise((resolve) => setTimeout(() => resolve(TIMEOUT), 3000)),
+          ]).then((res) => {
+            if (res === TIMEOUT && node.fiber === fiber) {
+              console.warn(timeoutError);
+            }
+          });
+        }
+        return result.catch(onError);
+      }
+      return result;
+    } catch (cause) {
+      onError(cause);
+    }
+  };
+}
+
+// -----------------------------------------------------------------------------
+//  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));
+}

src/runtime/portal.ts

@@ -0,0 +1,90 @@
+import { onMounted, onWillUnmount } from "./lifecycle_hooks";
+import { BDom, text, VNode } from "./blockdom";
+import { Component } from "./component";
+import { OwlError } from "./error_handling";
+
+const VText: any = text("").constructor;
+
+class VPortal extends VText implements Partial<VNode<VPortal>> {
+  content: BDom | null;
+  selector: string;
+  target: HTMLElement | null = null;
+
+  constructor(selector: string, content: BDom) {
+    super("");
+    this.selector = selector;
+    this.content = content;
+  }
+
+  mount(parent: HTMLElement, anchor: ChildNode) {
+    super.mount(parent, anchor);
+    this.target = document.querySelector(this.selector) as any;
+    if (this.target) {
+      this.content!.mount(this.target!, null);
+    } else {
+      this.content!.mount(parent, anchor);
+    }
+  }
+
+  beforeRemove() {
+    this.content!.beforeRemove();
+  }
+  remove() {
+    if (this.content) {
+      super.remove();
+      this.content!.remove();
+      this.content = null;
+    }
+  }
+
+  patch(other: VPortal) {
+    super.patch(other);
+    if (this.content) {
+      this.content.patch(other.content!, true);
+    } else {
+      this.content = other.content;
+      this.content!.mount(this.target!, null);
+    }
+  }
+}
+
+/**
+ * kind of similar to <t t-slot="default"/>, but it wraps it around a VPortal
+ */
+export function portalTemplate(app: any, bdom: any, helpers: any) {
+  let { callSlot } = helpers;
+  return function template(ctx: any, node: any, key = ""): any {
+    return new VPortal(ctx.props.target, callSlot(ctx, node, key, "default", false, null));
+  };
+}
+
+export class Portal extends Component {
+  static template = "__portal__";
+  static props = {
+    target: {
+      type: String,
+    },
+    slots: true,
+  };
+
+  setup() {
+    const node: any = this.__owl__;
+
+    onMounted(() => {
+      const portal: VPortal = node.bdom;
+      if (!portal.target) {
+        const target: HTMLElement = document.querySelector(this.props.target);
+        if (target) {
+          portal.content!.moveBeforeDOMNode(target.firstChild, target);
+        } else {
+          throw new OwlError("invalid portal target");
+        }
+      }
+    });
+
+    onWillUnmount(() => {
+      const portal: VPortal = node.bdom;
+      portal.remove();
+    });
+  }
+}

src/runtime/reactivity.ts

@@ -0,0 +1,464 @@
+import type { Callback } from "./utils";
+import { OwlError } from "./error_handling";
+
+// Special key to subscribe to, to be notified of key creation/deletion
+const KEYCHANGES = Symbol("Key changes");
+// Used to specify the absence of a callback, can be used as WeakMap key but
+// should only be used as a sentinel value and never called.
+const NO_CALLBACK = () => {
+  throw new Error("Called NO_CALLBACK. Owl is broken, please report this to the maintainers.");
+};
+
+// The following types only exist to signify places where objects are expected
+// to be reactive or not, they provide no type checking benefit over "object"
+type Target = object;
+type Reactive<T extends Target> = T;
+
+type Collection = Set<any> | Map<any, any> | WeakMap<any, any>;
+type CollectionRawType = "Set" | "Map" | "WeakMap";
+
+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(toRaw(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;
+}
+
+const skipped = new WeakSet<Target>();
+/**
+ * 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): T {
+  skipped.add(value);
+  return value;
+}
+
+/**
+ * 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 Target, U extends Reactive<T>>(value: U | T): T {
+  return targets.has(value) ? (targets.get(value) as T) : 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 (callback === NO_CALLBACK) {
+    return;
+  }
+  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 [key, callbacks] of observedKeys.entries()) {
+      callbacks.delete(callback);
+      if (!callbacks.size) {
+        observedKeys.delete(key);
+      }
+    }
+  }
+  targetsToClear.clear();
+}
+
+export function getSubscriptions(callback: Callback) {
+  const targets = callbacksToTargets.get(callback) || [];
+  return [...targets].map((target) => {
+    const keysToCallbacks = targetToKeysToCallbacks.get(target);
+    let keys = [];
+    if (keysToCallbacks) {
+      for (const [key, cbs] of keysToCallbacks) {
+        if (cbs.has(callback)) {
+          keys.push(key);
+        }
+      }
+    }
+    return { target, keys };
+  });
+}
+// Maps reactive objects to the underlying target
+export const targets = new WeakMap<Reactive<Target>, Target>();
+const reactiveCache = new WeakMap<Target, WeakMap<Callback, Reactive<Target>>>();
+/**
+ * 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's 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 = NO_CALLBACK): T {
+  if (!canBeMadeReactive(target)) {
+    throw new OwlError(`Cannot make the given value reactive`);
+  }
+  if (skipped.has(target)) {
+    return target;
+  }
+  if (targets.has(target)) {
+    // target is reactive, create a reactive on the underlying object instead
+    return reactive(targets.get(target) as T, 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);
+    targets.set(proxy, target);
+  }
+  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, key, receiver) {
+      // 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, receiver);
+      }
+      observeTargetKey(target, key, callback);
+      return possiblyReactive(Reflect.get(target, key, receiver), callback);
+    },
+    set(target, key, value, receiver) {
+      const hadKey = objectHasOwnProperty.call(target, key);
+      const originalValue = Reflect.get(target, key, receiver);
+      const ret = Reflect.set(target, key, value, receiver);
+      if (!hadKey && objectHasOwnProperty.call(target, key)) {
+        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 !== Reflect.get(target, key, receiver) ||
+        (key === "length" && Array.isArray(target))
+      ) {
+        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), {
+    // FIXME: probably broken when part of prototype chain since we ignore the receiver
+    get(target: any, key: PropertyKey) {
+      if (objectHasOwnProperty.call(specialHandlers, key)) {
+        return (specialHandlers as any)[key];
+      }
+      observeTargetKey(target, key, callback);
+      return possiblyReactive(target[key], callback);
+    },
+  }) as ProxyHandler<T>;
+}

src/runtime/scheduler.ts

@@ -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);
+    }
+  }
+}

src/runtime/template_helpers.ts

@@ -0,0 +1,283 @@
+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";
+import { OwlError } from "./error_handling";
+
+const ObjectCreate = Object.create;
+/**
+ * This file contains utility functions that will be injected in each template,
+ * to perform various useful tasks in the compiled code.
+ */
+
+function withDefault(value: any, defaultValue: any): any {
+  return value === undefined || value === null || value === false ? defaultValue : value;
+}
+
+function callSlot(
+  ctx: any,
+  parent: any,
+  key: string,
+  name: string,
+  dynamic: boolean,
+  extra: any,
+  defaultContent?: (ctx: any, node: any, key: string) => BDom
+): BDom {
+  key = key + "__slot_" + name;
+  const slots = ctx.props.slots || {};
+  const { __render, __ctx, __scope } = slots[name] || {};
+  const slotScope = ObjectCreate(__ctx || {});
+  if (__scope) {
+    slotScope[__scope] = extra;
+  }
+  const slotBDom = __render ? __render(slotScope, parent, key) : null;
+  if (defaultContent) {
+    let child1: BDom | undefined = undefined;
+    let child2: BDom | undefined = undefined;
+    if (slotBDom) {
+      child1 = dynamic ? toggler(name, slotBDom) : slotBDom;
+    } else {
+      child2 = defaultContent(ctx, parent, key);
+    }
+    return multi([child1, child2]);
+  }
+  return slotBDom || text("");
+}
+
+function capture(ctx: any): any {
+  const result = ObjectCreate(ctx);
+  for (let k in ctx) {
+    result[k] = ctx[k];
+  }
+  return result;
+}
+
+function withKey(elem: any, k: string) {
+  elem.key = k;
+  return elem;
+}
+
+function prepareList(collection: any): [any[], any[], number, any[]] {
+  let keys: any[];
+  let values: any[];
+
+  if (Array.isArray(collection)) {
+    keys = collection;
+    values = collection;
+  } else if (collection) {
+    values = Object.keys(collection);
+    keys = Object.values(collection);
+  } else {
+    throw new OwlError("Invalid loop expression");
+  }
+  const n = values.length;
+  return [keys, values, n, new Array(n)];
+}
+
+const isBoundary = Symbol("isBoundary");
+
+function setContextValue(ctx: { [key: string]: any }, key: string, value: any): void {
+  const ctx0 = ctx;
+  while (!ctx.hasOwnProperty(key) && !ctx.hasOwnProperty(isBoundary)) {
+    const newCtx = ctx.__proto__;
+    if (!newCtx) {
+      ctx = ctx0;
+      break;
+    }
+    ctx = newCtx;
+  }
+  ctx[key] = value;
+}
+
+function toNumber(val: string): number | string {
+  const n = parseFloat(val);
+  return isNaN(n) ? val : n;
+}
+
+function shallowEqual(l1: any[], l2: any[]): boolean {
+  for (let i = 0, l = l1.length; i < l; i++) {
+    if (l1[i] !== l2[i]) {
+      return false;
+    }
+  }
+  return true;
+}
+
+class LazyValue {
+  fn: any;
+  ctx: any;
+  component: any;
+  node: any;
+  key: any;
+
+  constructor(fn: any, ctx: any, component: any, node: any, key: any) {
+    this.fn = fn;
+    this.ctx = capture(ctx);
+    this.component = component;
+    this.node = node;
+    this.key = key;
+  }
+
+  evaluate(): any {
+    return this.fn.call(this.component, this.ctx, this.node, this.key);
+  }
+
+  toString() {
+    return this.evaluate().toString();
+  }
+}
+
+/*
+ * Safely outputs `value` as a block depending on the nature of `value`
+ */
+export function safeOutput(value: any, defaultValue?: any): ReturnType<typeof toggler> {
+  if (value === undefined) {
+    return defaultValue ? toggler("default", defaultValue) : toggler("undefined", text(""));
+  }
+  let safeKey;
+  let block;
+  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);
+}
+
+let boundFunctions = new WeakMap();
+const WeakMapGet = WeakMap.prototype.get;
+const WeakMapSet = WeakMap.prototype.set;
+
+function bind(component: any, fn: Function): Function {
+  let boundFnMap = WeakMapGet.call(boundFunctions, component);
+  if (!boundFnMap) {
+    boundFnMap = new WeakMap();
+    WeakMapSet.call(boundFunctions, component, boundFnMap);
+  }
+  let boundFn = WeakMapGet.call(boundFnMap, fn);
+  if (!boundFn) {
+    boundFn = fn.bind(component);
+    WeakMapSet.call(boundFnMap, fn, boundFn);
+  }
+  return boundFn;
+}
+
+type RefMap = { [key: string]: HTMLElement | null };
+type RefSetter = (el: HTMLElement | null) => void;
+
+function multiRefSetter(refs: RefMap, name: string): RefSetter {
+  let count = 0;
+  return (el) => {
+    if (el) {
+      count++;
+      if (count > 1) {
+        throw new OwlError("Cannot have 2 elements with same ref name at the same time");
+      }
+    }
+    if (count === 0 || el) {
+      refs[name] = el;
+    }
+  };
+}
+
+function singleRefSetter(refs: RefMap, name: string): RefSetter {
+  let _el: HTMLElement | null = null;
+  return (el) => {
+    if (el || refs[name] === _el) {
+      refs[name] = el;
+      _el = el;
+    }
+  };
+}
+
+/**
+ * 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, comp?: any) {
+  const ComponentClass =
+    typeof name !== "string"
+      ? name
+      : (comp.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 (comp.__owl__.app.warnIfNoStaticProps) {
+      console.warn(`Component '${ComponentClass.name}' does not have a static props description`);
+    }
+    return;
+  }
+  const defaultProps = ComponentClass.defaultProps;
+  if (defaultProps) {
+    let isMandatory = (name: string) =>
+      Array.isArray(schema)
+        ? schema.includes(name)
+        : name in schema && !("*" in schema) && !isOptional(schema[name]);
+    for (let p in defaultProps) {
+      if (isMandatory(p)) {
+        throw new OwlError(
+          `A default value cannot be defined for a mandatory prop (name: '${p}', component: ${ComponentClass.name})`
+        );
+      }
+    }
+  }
+
+  const errors = validateSchema(props, schema);
+  if (errors.length) {
+    throw new OwlError(
+      `Invalid props for component '${ComponentClass.name}': ` + errors.join(", ")
+    );
+  }
+}
+
+export const helpers = {
+  withDefault,
+  zero: Symbol("zero"),
+  isBoundary,
+  callSlot,
+  capture,
+  withKey,
+  prepareList,
+  setContextValue,
+  multiRefSetter,
+  singleRefSetter,
+  shallowEqual,
+  toNumber,
+  validateProps,
+  LazyValue,
+  safeOutput,
+  bind,
+  createCatcher,
+  markRaw,
+  OwlError,
+};

src/runtime/template_set.ts

@@ -1,11 +1,11 @@
-import { createBlock, html, list, multi, text, toggler, comment } from "../blockdom";
+import { compile, Template, TemplateFunction } from "../compiler";
-import { compile, Template } from "../compiler";
+import { comment, createBlock, html, list, multi, text, toggler } from "./blockdom";
-import { component } from "../component/component_node";
+import { getCurrent } from "./component_node";
-import { UTILS } from "./template_helpers";
+import { Portal, portalTemplate } from "./portal";
+import { helpers } from "./template_helpers";
+import { OwlError } from "./error_handling";
 
-const bdom = { text, createBlock, list, multi, html, toggler, component, comment };
+const bdom = { text, createBlock, list, multi, html, toggler, comment };
-
-export const globalTemplates: { [key: string]: string | Node } = {};
 
 function parseXML(xml: string): Document {
   const parser = new DOMParser();
@@ -32,7 +32,7 @@ function parseXML(xml: string): Document {
         }
       }
     }
-    throw new Error(msg);
+    throw new OwlError(msg);
   }
   return doc;
 }
@@ -45,18 +45,15 @@ 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, {
+  Portal = Portal;
-    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) => this.getTemplate(name),
-  });
 
   constructor(config: TemplateSetConfig = {}) {
     this.dev = config.dev || false;
@@ -67,14 +64,25 @@ export class TemplateSet {
     }
   }
 
-  addTemplate(name: string, template: string | Node, options: { allowDuplicate?: boolean } = {}) {
+  addTemplate(name: string, template: string | Element) {
-    if (name in this.rawTemplates && !options.allowDuplicate) {
+    if (name in this.rawTemplates) {
-      throw new Error(`Template ${name} already defined`);
+      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 OwlError(`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;
@@ -82,8 +90,7 @@ 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);
-      this.addTemplate(name, template, options);
     }
   }
 
@@ -91,34 +98,42 @@ export class TemplateSet {
     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 OwlError(`Missing template: "${name}"${extraInfo}`);
       }
-      const templateFn = this._compileTemplate(name, rawTemplate);
+      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) {
+  _compileTemplate(name: string, template: string | Element): ReturnType<typeof compile> {
-    return compile(template, {
+    throw new OwlError(`Unable to compile a template. Please use owl full build instead`);
-      name,
+  }
-      dev: this.dev,
+
-      translateFn: this.translateFn,
+  callTemplate(owner: any, subTemplate: string, ctx: any, parent: any, key: any): any {
-      translatableAttributes: this.translatableAttributes,
+    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);
@@ -127,3 +142,5 @@ export function xml(...args: Parameters<typeof String.raw>) {
 }
 
 xml.nextId = 1;
+
+TemplateSet.registerTemplate("__portal__", portalTemplate);

src/runtime/utils.ts

@@ -1,3 +1,4 @@
+import { OwlError } from "./error_handling";
 export type Callback = () => void;
 
 /**
@@ -15,15 +16,32 @@ 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
+      // so that only the first call to the batched function calls the original callback.
-      await Promise.resolve();
+      // Schedule this before calling the callback so that calls to the batched function
-      called = false;
+      // 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) {
+  // Get the document and HTMLElement corresponding to the target to allow mounting in iframes
+  const document = target && target.ownerDocument;
+  if (document) {
+    const HTMLElement = document.defaultView!.HTMLElement;
+    if (target instanceof HTMLElement) {
+      if (!document.body.contains(target)) {
+        throw new OwlError("Cannot mount a component on a detached dom node");
+      }
+      return;
+    }
+  }
+  throw new OwlError("Cannot mount component: the target is not a valid DOM element");
+}
+
 export class EventBus extends EventTarget {
   trigger(name: string, payload?: any) {
     this.dispatchEvent(new CustomEvent(name, { detail: payload }));
@@ -43,7 +61,7 @@ export function whenReady(fn?: any): Promise<void> {
 export async function loadFile(url: string): Promise<string> {
   const result = await fetch(url);
   if (!result.ok) {
-    throw new Error("Error while fetching xml templates");
+    throw new OwlError("Error while fetching xml templates");
   }
   return await result.text();
 }

src/runtime/validation.ts

@@ -0,0 +1,171 @@
+import { OwlError } from "./error_handling";
+import { toRaw } from "./reactivity";
+
+type BaseType =
+  | typeof String
+  | typeof Boolean
+  | typeof Number
+  | typeof Date
+  | typeof Object
+  | typeof Array
+  | true
+  | "*";
+
+interface TypeInfo {
+  type?: TypeDescription;
+  optional?: boolean;
+  validate?: Function;
+  shape?: Schema;
+  element?: TypeDescription;
+}
+
+type ValueType = { value: any };
+
+type TypeDescription = BaseType | TypeInfo | ValueType | TypeDescription[];
+type SimplifiedSchema = string[];
+type NormalizedSchema = { [key: string]: TypeDescription };
+export type Schema = SimplifiedSchema | NormalizedSchema;
+
+// -----------------------------------------------------------------------------
+// helpers
+// -----------------------------------------------------------------------------
+const isUnionType = (t: TypeDescription): t is TypeDescription[] => Array.isArray(t);
+const isBaseType = (t: TypeDescription): t is BaseType => typeof t !== "object";
+const isValueType = (t: TypeDescription): t is ValueType =>
+  typeof t === "object" && t && "value" in t;
+
+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 ");
+  } else if (isValueType(info)) {
+    return String(info.value);
+  }
+  if ("element" in info) {
+    return `list of ${describe({ type: info.element, optional: false })}s`;
+  }
+  if ("shape" in (info as TypeInfo)) {
+    return `object`;
+  }
+  return describe(info.type || "*");
+}
+
+function toSchema(spec: SimplifiedSchema): NormalizedSchema {
+  return Object.fromEntries(
+    spec.map((e) =>
+      e.endsWith("?") ? [e.slice(0, -1), { optional: true }] : [e, { type: "*", optional: false }]
+    )
+  );
+}
+
+/**
+ * Main validate function
+ */
+export function validate(obj: { [key: string]: any }, spec: Schema) {
+  let errors = validateSchema(obj, spec);
+  if (errors.length) {
+    throw new OwlError("Invalid object: " + errors.join(", "));
+  }
+}
+
+/**
+ * Helper validate function, to get the list of errors. useful if one want to
+ * manipulate the errors without parsing an error object
+ */
+export function validateSchema(obj: { [key: string]: any }, schema: Schema): string[] {
+  if (Array.isArray(schema)) {
+    schema = toSchema(schema);
+  }
+  obj = toRaw(obj);
+  let errors = [];
+  // check if each value in obj has correct shape
+  for (let key in obj) {
+    if (key in schema) {
+      let result = validateType(key, obj[key], schema[key]);
+      if (result) {
+        errors.push(result);
+      }
+    } else if (!("*" in schema)) {
+      errors.push(`unknown key '${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 ${describe(descr)})`;
+  } else if (isBaseType(descr)) {
+    return validateBaseType(key, value, descr);
+  } else if (isValueType(descr)) {
+    return value === descr.value ? null : `'${key}' is not equal to '${descr.value}'`;
+  } else if (isUnionType(descr)) {
+    let validDescr = descr.find((p) => !validateType(key, value, p));
+    return validDescr ? null : `'${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;
+}

tests/__snapshots__/reactivity.test.ts.snap

@@ -47,16 +47,17 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  const comp1 = app.createComponent(\`Child\`, true, false, false, true);
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
     let b2;
     if (ctx['state'].flag) {
-      b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+      b2 = comp1({}, key + \`__1\`, node, this, null);
     }
     return block1([], [b2]);
   }
@@ -64,9 +65,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<span><block-text-0/></span>\`);
   
@@ -78,16 +79,17 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  const comp1 = app.createComponent(\`Child\`, true, false, false, true);
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
     let b2;
     if (ctx['state'].flag) {
-      b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+      b2 = comp1({}, key + \`__1\`, node, this, null);
     }
     return block1([], [b2]);
   }
@@ -95,9 +97,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<span><block-text-0/></span>\`);
   
@@ -109,9 +111,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><block-text-0/><block-text-1/></div>\`);
   
@@ -124,14 +126,15 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  const comp1 = app.createComponent(\`Child\`, true, false, false, true);
   
   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 = comp1({}, key + \`__1\`, node, this, null);
     let txt1 = ctx['contextObj'].b;
     return block1([txt1], [b2]);
   }
@@ -139,9 +142,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<span><block-text-0/></span>\`);
   
@@ -216,24 +219,26 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  const comp1 = app.createComponent(\`Child\`, true, false, false, true);
+  const comp2 = app.createComponent(\`Child\`, true, false, false, true);
   
   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);
+    const b2 = comp1({}, key + \`__1\`, node, this, null);
-    let b3 = component(\`Child\`, {}, key + \`__2\`, node, ctx);
+    const b3 = comp2({}, key + \`__2\`, node, this, null);
     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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<span><block-text-0/></span>\`);
   
@@ -245,24 +250,26 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  const comp1 = app.createComponent(\`Child\`, true, false, false, true);
+  const comp2 = app.createComponent(\`Child\`, true, false, false, true);
   
   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);
+    const b2 = comp1({}, key + \`__1\`, node, this, null);
-    let b3 = component(\`Child\`, {}, key + \`__2\`, node, ctx);
+    const b3 = comp2({}, key + \`__2\`, node, this, null);
     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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<span><block-text-0/></span>\`);
   
@@ -274,24 +281,26 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  const comp1 = app.createComponent(\`Child\`, true, false, false, true);
+  const comp2 = app.createComponent(\`Parent\`, true, false, false, true);
   
   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);
+    const b2 = comp1({}, key + \`__1\`, node, this, null);
-    let b3 = component(\`Parent\`, {}, key + \`__2\`, node, ctx);
+    const b3 = comp2({}, key + \`__2\`, node, this, null);
     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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<span><block-text-0/></span>\`);
   
@@ -303,23 +312,24 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  const comp1 = app.createComponent(\`Child\`, true, false, false, true);
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    const b2 = comp1({}, key + \`__1\`, node, this, null);
     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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><block-text-0/></div>\`);
   
@@ -331,23 +341,24 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { prepareList, withKey } = helpers;
+  const comp1 = app.createComponent(\`Quantity\`, true, false, false, false);
   
   let block1 = createBlock(\`<div><block-child-0/> Total: <block-text-0/> Count: <block-text-1/></div>\`);
   
   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);
+      c_block2[i1] = withKey(comp1({id: ctx['id']}, key + \`__1__\${key1}\`, node, this, null), 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]);
@@ -356,9 +367,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><block-text-0/></div>\`);
   
@@ -370,9 +381,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><block-text-0/></div>\`);
   

tests/app/__snapshots__/app.test.ts.snap

@@ -1,9 +1,9 @@
 // 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><block-text-0/> <block-text-1/></div>\`);
   
@@ -16,9 +16,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><block-text-0/></div>\`);
   
@@ -29,10 +29,23 @@ exports[`app can configure an app with props 1`] = `
 }"
 `;
 
-exports[`app destroy remove the widget from the DOM 1`] = `
+exports[`app can mount app in an iframe 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
-  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  let block1 = createBlock(\`<div class=\\"my-div\\"/>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    return block1();
+  }
+}"
+`;
+
+exports[`app destroy remove the widget from the DOM 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div/>\`);
   
@@ -41,3 +54,17 @@ 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, comment } = bdom;
+  
+  let block1 = createBlock(\`<div><block-text-0/></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let txt1 = ctx['message'];
+    return block1([txt1]);
+  }
+}"
+`;

tests/app/app.test.ts

@@ -1,5 +1,5 @@
-import { App, Component, xml } from "../../src";
+import { App, Component, mount, xml } from "../../src";
-import { status } from "../../src/component/status";
+import { status } from "../../src/runtime/status";
 import { makeTestFixture, snapshotEverything, nextTick, elem } from "../helpers";
 
 let fixture: HTMLElement;
@@ -59,4 +59,39 @@ 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"
+    );
+  });
+
+  test("can mount app in an iframe", async () => {
+    class SomeComponent extends Component {
+      static template = xml`<div class="my-div"/>`;
+    }
+
+    const iframe = document.createElement("iframe");
+    fixture.appendChild(iframe);
+    const app = new App(SomeComponent);
+    const iframeDoc = iframe.contentDocument!;
+    const comp = await app.mount(iframeDoc.body);
+    const div = iframeDoc.querySelector(".my-div");
+    expect(div).not.toBe(null);
+    expect(iframeDoc.contains(div)).toBe(true);
+    app.destroy();
+    expect(iframeDoc.contains(div)).toBe(false);
+    expect(status(comp)).toBe("destroyed");
+  });
 });

tests/blockdom/block.test.ts

@@ -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";
 
 //------------------------------------------------------------------------------

tests/blockdom/block_attributes.test.ts

@@ -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"/>`);

tests/blockdom/block_event_handling.test.ts

@@ -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";
 

tests/blockdom/block_refs.test.ts

@@ -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();
+});

tests/blockdom/comment.test.ts

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

tests/blockdom/event_catcher.test.ts

@@ -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);
+});

tests/blockdom/html.test.ts

@@ -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";
 
 //------------------------------------------------------------------------------

tests/blockdom/list.test.ts

@@ -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";
 
 //------------------------------------------------------------------------------

tests/blockdom/multi.test.ts

@@ -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";
 
 //------------------------------------------------------------------------------

tests/blockdom/namespace.test.ts

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

tests/blockdom/remove_hook.test.ts

@@ -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";
 
 //------------------------------------------------------------------------------

tests/blockdom/text.test.ts

@@ -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";
 
 //------------------------------------------------------------------------------

tests/blockdom/toggler.test.ts

@@ -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";
 
 //------------------------------------------------------------------------------

tests/compiler/__snapshots__/attributes.test.ts.snap

@@ -1,9 +1,9 @@
 // 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div class=\\"hoy\\" block-attribute-0=\\"class\\"/>\`);
   
@@ -15,9 +15,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div block-attribute-0=\\"class\\"/>\`);
   
@@ -29,9 +29,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div block-attribute-0=\\"value\\"/>\`);
   
@@ -43,9 +43,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div block-attribute-0=\\"class\\" class=\\"hello\\"/>\`);
   
@@ -57,9 +57,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div class=\\"hello\\" block-attribute-0=\\"class\\"/>\`);
   
@@ -71,9 +71,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div block-attribute-0=\\"foo\\"/>\`);
   
@@ -85,9 +85,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div block-attribute-0=\\"foo\\"/>\`);
   
@@ -99,9 +99,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div block-attribute-0=\\"data-action-id\\"/>\`);
   
@@ -113,9 +113,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div block-attribute-0=\\"foo\\"/>\`);
   
@@ -126,10 +126,24 @@ exports[`attributes dynamic attributes 1`] = `
 }"
 `;
 
-exports[`attributes dynamic class attribute 1`] = `
+exports[`attributes dynamic attributes with backticks 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
-  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  let block1 = createBlock(\`<div block-attribute-0=\\"foo\\"/>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let attr1 = \`bar\`;
+    return block1([attr1]);
+  }
+}"
+`;
+
+exports[`attributes dynamic class attribute 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div block-attribute-0=\\"class\\"/>\`);
   
@@ -141,9 +155,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div block-attribute-0=\\"class\\"/>\`);
   
@@ -154,10 +168,52 @@ exports[`attributes dynamic class attribute evaluating to 0 1`] = `
 }"
 `;
 
-exports[`attributes dynamic empty class attribute 1`] = `
+exports[`attributes dynamic class attribute that starts and ends with a space 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
-  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  let block1 = createBlock(\`<div block-attribute-0=\\"class\\"/>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let attr1 = ctx['c'];
+    return block1([attr1]);
+  }
+}"
+`;
+
+exports[`attributes dynamic class attribute which is only a space 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  let block1 = createBlock(\`<div block-attribute-0=\\"class\\"/>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let attr1 = ctx['c'];
+    return block1([attr1]);
+  }
+}"
+`;
+
+exports[`attributes dynamic class attribute with multiple consecutive spaces 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  let block1 = createBlock(\`<div block-attribute-0=\\"class\\"/>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let attr1 = ctx['c'];
+    return block1([attr1]);
+  }
+}"
+`;
+
+exports[`attributes dynamic empty class attribute 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div block-attribute-0=\\"class\\"/>\`);
   
@@ -169,9 +225,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div block-attribute-0=\\"aria-label\\"/>\`);
   
@@ -183,9 +239,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div block-attribute-0=\\"class\\"/>\`);
   
@@ -197,9 +253,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div block-attribute-0=\\"thing\\"/>\`);
   
@@ -211,9 +267,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div block-attribute-0=\\"foo\\"/>\`);
   
@@ -225,9 +281,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div block-attribute-0=\\"foo\\"/>\`);
   
@@ -239,9 +295,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div block-attribute-0=\\"foo\\"/>\`);
   
@@ -253,9 +309,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div block-attribute-0=\\"foo\\"/>\`);
   
@@ -267,9 +323,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div block-attribute-0=\\"foo\\"/>\`);
   
@@ -281,9 +337,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue } = helpers;
   
   let block1 = createBlock(\`<div><span block-attribute-0=\\"class\\"/></div>\`);
@@ -299,9 +355,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue } = helpers;
   
   let block1 = createBlock(\`<span block-attribute-0=\\"class\\"/>\`);
@@ -317,9 +373,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue } = helpers;
   
   let block1 = createBlock(\`<div><span block-attribute-0=\\"class\\"/></div>\`);
@@ -335,9 +391,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div block-attributes=\\"0\\"/>\`);
   
@@ -349,9 +405,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div foo=\\"a\\" bar=\\"b\\" baz=\\"c\\"/>\`);
   
@@ -362,9 +418,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<img src=\\"/test.skip.jpg\\" alt=\\"Test\\"/>\`);
   
@@ -374,10 +430,36 @@ exports[`attributes static attributes on void elements 1`] = `
 }"
 `;
 
-exports[`attributes static attributes with dashes 1`] = `
+exports[`attributes static attributes with backslash or backtick 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
-  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  let block1 = createBlock(\`<div foo=\\"\\\\\\\\a\\" bar=\\"\\\\\\\\n\\" baz=\\"\\\\\`\\"/>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    return block1();
+  }
+}"
+`;
+
+exports[`attributes static attributes with backticks 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  let block1 = createBlock(\`<div foo=\\"\\\\\`bar\\\\\`\\"/>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    return block1();
+  }
+}"
+`;
+
+exports[`attributes static attributes with dashes 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div aria-label=\\"Close\\"/>\`);
   
@@ -387,10 +469,24 @@ exports[`attributes static attributes with dashes 1`] = `
 }"
 `;
 
-exports[`attributes t-att-class and class should combine together 1`] = `
+exports[`attributes string interpolation, alternate syntax 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
-  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { text, createBlock, list, multi, html, toggler, 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(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div class=\\"hello\\" block-attribute-0=\\"class\\"/>\`);
   
@@ -402,9 +498,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div block-attribute-0=\\"class\\"/>\`);
   
@@ -416,9 +512,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div block-attribute-0=\\"class\\"/>\`);
   
@@ -429,10 +525,24 @@ exports[`attributes t-att-class with multiple classes 2`] = `
 }"
 `;
 
-exports[`attributes t-att-class with multiple classes, some of which are duplicate 1`] = `
+exports[`attributes t-att-class with multiple classes 3`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
-  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  let block1 = createBlock(\`<div block-attribute-0=\\"class\\"/>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let attr1 = {'a  b  c':ctx['value']};
+    return block1([attr1]);
+  }
+}"
+`;
+
+exports[`attributes t-att-class with multiple classes, some of which are duplicate 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div block-attribute-0=\\"class\\"/>\`);
   
@@ -444,9 +554,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div class=\\"static\\" block-attribute-0=\\"class\\"/>\`);
   
@@ -457,10 +567,38 @@ exports[`attributes t-att-class with object 1`] = `
 }"
 `;
 
-exports[`attributes t-attf-class 1`] = `
+exports[`attributes t-att-class with object 2`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
-  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  let block1 = createBlock(\`<div block-attribute-0=\\"class\\"/>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let attr1 = {' a ':ctx['value']};
+    return block1([attr1]);
+  }
+}"
+`;
+
+exports[`attributes t-att-class with object 3`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  let block1 = createBlock(\`<div block-attribute-0=\\"class\\"/>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let attr1 = {' ':ctx['value']};
+    return block1([attr1]);
+  }
+}"
+`;
+
+exports[`attributes t-attf-class 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div block-attribute-0=\\"class\\"/>\`);
   
@@ -472,9 +610,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div class=\\"hello\\" block-attribute-0=\\"class\\"/>\`);
   
@@ -486,9 +624,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div block-attribute-0=\\"class\\"/>\`);
   
@@ -500,9 +638,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div block-attribute-0=\\"class\\"/>\`);
   
@@ -514,9 +652,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div block-attributes=\\"0\\"/>\`);
   
@@ -528,9 +666,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div block-attributes=\\"0\\"/>\`);
   
@@ -542,9 +680,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div class=\\"a b\\"/>\`);
   
@@ -555,9 +693,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div block-attribute-0=\\"foo\\" block-attribute-1=\\"bar\\"/>\`);
   
@@ -570,9 +708,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div class=\\"hoy\\" block-attribute-0=\\"class\\"/>\`);
   
@@ -583,10 +721,24 @@ exports[`attributes updating classes (with obj notation) 1`] = `
 }"
 `;
 
-exports[`attributes various escapes 1`] = `
+exports[`attributes updating property with falsy value 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
-  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  let block1 = createBlock(\`<input block-attribute-0=\\"value\\"/>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let attr1 = new String((ctx['v']) || \\"\\");
+    return block1([attr1]);
+  }
+}"
+`;
+
+exports[`attributes various escapes 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div foo=\\"&lt;foo\\" block-attribute-0=\\"bar\\" block-attribute-1=\\"baz\\" block-attributes=\\"2\\"/>\`);
   
@@ -600,9 +752,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div> &lt; </div>\`);
   
@@ -613,79 +765,107 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<input type=\\"checkbox\\" block-attribute-0=\\"indeterminate\\"/>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let attr1 = ctx['v'];
+    let attr1 = new Boolean(ctx['v']);
     return block1([attr1]);
   }
 }"
 `;
 
 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<input type=\\"checkbox\\" block-attribute-0=\\"checked\\"/>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let attr1 = ctx['flag'];
+    let attr1 = new Boolean(ctx['flag']);
+    return block1([attr1]);
+  }
+}"
+`;
+
+exports[`special cases for some specific html attributes/properties input with t-att-value (patching with same value 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  let block1 = createBlock(\`<input block-attribute-0=\\"value\\"/>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let attr1 = new String((ctx['v']) || \\"\\");
     return block1([attr1]);
   }
 }"
 `;
 
 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<input block-attribute-0=\\"value\\"/>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let attr1 = ctx['v'];
+    let attr1 = new String((ctx['v']) || \\"\\");
+    return block1([attr1]);
+  }
+}"
+`;
+
+exports[`special cases for some specific html attributes/properties input, type checkbox, with t-att-checked (patching with same value 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  let block1 = createBlock(\`<input type=\\"checkbox\\" block-attribute-0=\\"checked\\"/>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let attr1 = new Boolean(ctx['v']);
     return block1([attr1]);
   }
 }"
 `;
 
 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<select block-attribute-0=\\"value\\"><option value=\\"potato\\">Potato</option><option value=\\"tomato\\">Tomato</option><option value=\\"onion\\">Onion</option></select>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let attr1 = ctx['value'];
+    let attr1 = new String((ctx['value']) || \\"\\");
     return block1([attr1]);
   }
 }"
 `;
 
 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<textarea block-attribute-0=\\"value\\"/>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let attr1 = ctx['v'];
+    let attr1 = new String((ctx['v']) || \\"\\");
     return block1([attr1]);
   }
 }"
 `;
 
 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><input type=\\"checkbox\\" checked=\\"checked\\"/><input checked=\\"checked\\"/><div checked=\\"checked\\"/><div selected=\\"selected\\"/><option selected=\\"selected\\" other=\\"1\\"/><input readonly=\\"readonly\\"/><button disabled=\\"disabled\\"/></div>\`);
   

tests/compiler/__snapshots__/comments.test.ts.snap

@@ -1,9 +1,9 @@
 // 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
     return comment(\` comment\`);
@@ -12,9 +12,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div>hello <!-- comment-->owl</div>\`);
   
@@ -25,9 +25,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><block-child-0/><block-child-1/></div>\`);
   let block2 = createBlock(\`<span>true</span>\`);

tests/compiler/__snapshots__/event_handling.test.ts.snap

@@ -1,9 +1,9 @@
 // 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<button block-handler-0=\\"click\\">Click</button>\`);
   
@@ -15,9 +15,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<button block-handler-0=\\"click\\">Click</button>\`);
   
@@ -30,9 +30,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<button block-handler-0=\\"click\\">Click</button>\`);
   
@@ -45,9 +45,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<button block-handler-0=\\"click\\">Click</button>\`);
   
@@ -60,9 +60,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { prepareList, withKey } = helpers;
   
   let block1 = createBlock(\`<ul><block-child-0/></ul>\`);
@@ -70,26 +70,26 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<button block-handler-0=\\"click\\">Click</button>\`);
   
@@ -102,9 +102,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<button block-handler-0=\\"click\\" block-handler-1=\\"dblclick\\">Click</button>\`);
   
@@ -117,9 +117,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<button block-handler-0=\\"click\\">Click</button>\`);
   
@@ -131,19 +131,19 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { prepareList, withKey } = helpers;
   
   let block2 = createBlock(\`<button block-handler-0=\\"click\\">Click</button>\`);
   
   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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
-  let { getTemplate } = helpers;
+  const callTemplate_1 = app.getTemplate(\`sub\`);
-  const callTemplate_1 = getTemplate(\`sub\`);
   
   return function template(ctx, node, key = \\"\\") {
     return callTemplate_1.call(this, ctx, node, key + \`__1\`);
@@ -166,9 +165,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<button block-handler-0=\\"click\\">Click</button>\`);
   
@@ -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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
-  let { prepareList, getTemplate, withKey } = helpers;
+  let { prepareList, withKey } = helpers;
-  const callTemplate_1 = getTemplate(\`sub\`);
+  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);
@@ -204,9 +203,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<button block-handler-0=\\"click\\">Click</button>\`);
   
@@ -218,9 +217,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<button block-handler-0=\\"click\\">Click</button>\`);
   
@@ -232,9 +231,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div class=\\"myClass\\" block-handler-0=\\"click\\"><button block-handler-1=\\"click\\">Button</button></div>\`);
   
@@ -247,9 +246,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><button block-handler-0=\\"click\\"><block-text-1/></button></div>\`);
   
@@ -262,25 +261,25 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { safeOutput } = helpers;
   
   let block1 = createBlock(\`<div><button block-handler-0=\\"click\\"><block-child-0/></button></div>\`);
   
   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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div block-handler-0=\\"click.capture\\"><button block-handler-1=\\"click\\">Button</button></div>\`);
   
@@ -293,9 +292,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><button block-handler-0=\\"click.prevent\\">Button</button></div>\`);
   
@@ -307,9 +306,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><button block-handler-0=\\"click.prevent.self\\"><span>Button</span></button></div>\`);
   
@@ -321,9 +320,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><button block-handler-0=\\"click.prevent\\">Button 1</button><button block-handler-1=\\"click.stop\\">Button 2</button><button block-handler-2=\\"click.prevent.stop\\">Button 3</button></div>\`);
   
@@ -337,9 +336,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { prepareList, withKey } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
@@ -347,26 +346,26 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><button block-handler-0=\\"click.self.prevent\\"><span>Button</span></button></div>\`);
   
@@ -378,9 +377,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><button block-handler-0=\\"click\\"><span>Button</span></button><button block-handler-1=\\"click.self\\"><span>Button</span></button></div>\`);
   
@@ -393,9 +392,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div block-handler-0=\\"click.synthetic\\"><button block-handler-1=\\"click.synthetic\\">Button</button></div>\`);
   
@@ -408,9 +407,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<button block-handler-0=\\"click\\">Click</button>\`);
   
@@ -423,9 +422,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<button block-handler-0=\\"click\\">Click</button>\`);
   
@@ -438,9 +437,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<button block-handler-0=\\"click\\">Toggle</button>\`);
   
@@ -453,9 +452,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<button block-handler-0=\\"click\\">Toggle</button>\`);
   
@@ -469,25 +468,24 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
-  let { getTemplate } = helpers;
+  const callTemplate_1 = app.getTemplate(\`sub\`);
-  const callTemplate_1 = 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<p block-handler-0=\\"click\\">lucas</p>\`);
   
@@ -499,31 +497,31 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
-  let { getTemplate } = helpers;
+  const callTemplate_1 = app.getTemplate(\`sub\`);
-  const callTemplate_1 = 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<p block-handler-0=\\"click\\">lucas</p>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const v1 = ctx['value'];
+    const v1 = ctx['this'];
-    let hdlr1 = [()=>this.update(v1), ctx];
+    const v2 = ctx['value'];
+    let hdlr1 = [()=>v1.update(v2), ctx];
     return block1([hdlr1]);
   }
 }"

tests/compiler/__snapshots__/misc.test.ts.snap

@@ -1,10 +1,11 @@
 // 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { prepareList, withKey } = helpers;
+  const comp1 = app.createComponent(\`SlotButton\`, true, false, false, false);
   
   let block1 = createBlock(\`<div block-attribute-0=\\"class\\"><div block-attribute-1=\\"class\\"><div class=\\"batch_header\\"><a block-attribute-2=\\"href\\" block-attribute-3=\\"class\\" title=\\"View Batch\\"><block-text-4/><block-child-0/><i class=\\"arrow fa fa-window-maximize\\"/></a></div><block-child-1/><div class=\\"batch_slots\\"><block-child-2/><block-child-3/></div><div class=\\"batch_commits\\"><block-child-4/></div></div></div>\`);
   let block2 = createBlock(\`<i class=\\"fa fa-exclamation-triangle\\"/>\`);
@@ -30,28 +31,28 @@ 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);
+      c_block4[i1] = withKey(comp1({class: ctx['slot_container'],slot: ctx['slot']}, key + \`__1__\${key1}\`, node, this, null), 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 +80,15 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
-  let { prepareList, isBoundary, withDefault, setContextValue, getTemplate, zero, withKey } = helpers;
+  let { prepareList, isBoundary, withDefault, setContextValue, zero, withKey } = helpers;
-  const callTemplate_1 = getTemplate(\`_callee-uses-foo\`);
+  const callTemplate_1 = app.getTemplate(\`_callee-uses-foo\`);
-  const callTemplate_2 = getTemplate(\`_callee-uses-foo\`);
+  const callTemplate_2 = app.getTemplate(\`_callee-uses-foo\`);
-  const callTemplate_3 = getTemplate(\`_callee-uses-foo\`);
+  const callTemplate_3 = app.getTemplate(\`_callee-uses-foo\`);
-  const callTemplate_4 = getTemplate(\`_callee-asc\`);
+  const callTemplate_4 = app.getTemplate(\`_callee-asc\`);
-  const callTemplate_5 = getTemplate(\`_callee-asc-toto\`);
+  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>\`);
@@ -96,44 +97,44 @@ 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}\`);
+      const b8 = callTemplate_3.call(this, ctx, node, key + \`__3__\${key1}\`);
-      let b5 = multi([b6, b7, b8]);
+      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);
+    const b2 = list(c_block2);
-    let b10 = callTemplate_5.call(this, ctx, node, key + \`__5\`);
+    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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { withDefault } = helpers;
   
   let block1 = createBlock(\`<span><block-text-0/></span>\`);
@@ -146,43 +147,45 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { zero } = helpers;
   
   let block1 = createBlock(\`<año block-attribute-0=\\"falló\\"><block-child-0/></año>\`);
   
   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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
-  let { safeOutput, withDefault } = helpers;
+  let { safeOutput } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b3 = text(\`toto default\`);
+    const b3 = text(\`toto default\`);
-    let b2 = withDefault(safeOutput(ctx['toto']), b3);
+    const b2 = 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
-  let { prepareList, withKey, getTemplate } = helpers;
+  let { prepareList, withKey, singleRefSetter } = helpers;
-  const callTemplate_1 = getTemplate(\`LOAD_INFOS_TEMPLATE\`);
+  const callTemplate_1 = app.getTemplate(\`LOAD_INFOS_TEMPLATE\`);
+  const comp1 = app.createComponent(\`BundlesList\`, true, false, false, false);
+  const comp2 = app.createComponent(\`BundlesList\`, true, false, false, false);
   
   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>
@@ -214,17 +217,17 @@ exports[`misc other complex template 1`] = `
   let block25 = createBlock(\`<div><block-child-0/><block-child-1/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const refs = ctx.__owl__.refs;
+    const refs = this.__owl__.refs;
-    const ref1 = (el) => refs[\`search_input\`] = el;
+    const ref1 = singleRefSetter(refs, \`search_input\`);
-    const ref2 = (el) => refs[\`settings_menu\`] = el;
+    const ref2 = singleRefSetter(refs, \`settings_menu\`);
     let b2,b4,b14,b17,b22,b23,b24,b25;
     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 +244,12 @@ 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]);
+          const b8 = block8([attr3, txt3]);
-          let b9 = block9();
+          const b9 = block9();
           b7 = multi([b8, b9]);
         } else if (ctx['nb_build_errors']&&ctx['nb_build_errors']>0) {
-          let b11 = block11();
+          const b11 = block11();
-          let b12 = block12();
+          const b12 = block12();
           b10 = multi([b11, b12]);
         }
         let txt4 = ctx['user'].name.length>25?ctx['user'].namesubstring(0,23)+'...':ctx['user'].name;
@@ -261,34 +264,34 @@ 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 attr7 = new Boolean(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;
+    let attr8 = new String((ctx['search'].value) || \\"\\");
     let hdlr4 = [ctx['updateFilter'], ctx];
     let hdlr5 = [ctx['updateFilter'], ctx];
     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}\`;
           let attr10 = \`trigger_\${ctx['trigger'].id}\`;
-          let attr11 = ctx['options'].trigger_display[ctx['trigger'].id];
+          let attr11 = new Boolean(ctx['options'].trigger_display[ctx['trigger'].id]);
           let attr12 = ctx['trigger'].id;
           let hdlr7 = [ctx['updateTriggerDisplay'], ctx];
           let attr13 = \`trigger_\${ctx['trigger'].id}\`;
@@ -298,12 +301,12 @@ 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 +319,8 @@ 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);
+      const b26 = comp1({bundles: ctx['bundles'].sticky,category_custom_views: ctx['category_custom_views'],search: ctx['search']}, key + \`__2\`, node, this, null);
-      let b27 = component(\`BundlesList\`, {bundles: ctx['bundles'].dev,search: ctx['search']}, key + \`__3\`, node, ctx);
+      const b27 = comp2({bundles: ctx['bundles'].dev,search: ctx['search']}, key + \`__3\`, node, this, null);
       b25 = block25([], [b26, b27]);
     }
     return block1([attr1, txt1, hdlr2, hdlr3, attr8, hdlr4, hdlr5, ref1, hdlr6, ref2], [b2, b4, b14, b17, b22, b23, b24, b25]);

tests/compiler/__snapshots__/qweb_memory.test.ts.snap

@@ -1,23 +1,23 @@
 // 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { prepareList, withKey } = helpers;
   
   let block1 = createBlock(\`<p><block-child-0/></p>\`);
   
   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]);
   }
 }"

tests/compiler/__snapshots__/simple_templates.test.ts.snap

@@ -1,9 +1,9 @@
 // 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<tr><td>cell</td></tr>\`);
   
@@ -14,9 +14,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div class=\\"abc\\">foo</div>\`);
   
@@ -27,9 +27,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div class=\\"a'bc\\">word</div>\`);
   
@@ -40,9 +40,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><span>word</span></div>\`);
   
@@ -53,9 +53,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div abc=\\"a'bc\\">word</div>\`);
   
@@ -66,9 +66,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div>word</div>\`);
   
@@ -79,9 +79,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div>foo</div>\`);
   
@@ -92,9 +92,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><block-text-0/></div>\`);
   
@@ -106,9 +106,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><block-text-0/></div>\`);
   
@@ -120,9 +120,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
     return text(ctx['text']);
@@ -131,9 +131,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div/>\`);
   
@@ -144,9 +144,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
     return text(\`\`);
@@ -155,9 +155,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
     return text(\`\`);
@@ -166,9 +166,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
     return text(\`text\`);
@@ -177,9 +177,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue } = helpers;
   
   return function template(ctx, node, key = \\"\\") {
@@ -192,9 +192,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
     return text(\`text \${ctx['v']}\`);
@@ -203,25 +203,25 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block2 = createBlock(\`<div>foo</div>\`);
   let block3 = createBlock(\`<span>hey</span>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = block2();
+    const b2 = block2();
-    let b3 = block3();
+    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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
     return text(\`hello vdom\`);
@@ -230,9 +230,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
     return text(\`hello vdom\`);
@@ -241,35 +241,35 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = text(\`hello \`);
+    const b2 = text(\`hello \`);
-    let b3 = text(ctx['text']);
+    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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = text(\`hello \`);
+    const b2 = text(\`hello \`);
-    let b3 = text(ctx['text']);
+    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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><block-text-0/></div>\`);
   
@@ -281,9 +281,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div>hello <block-text-0/></div>\`);
   
@@ -295,9 +295,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div>hello <block-text-0/> world</div>\`);
   
@@ -309,9 +309,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><block-text-0/><block-text-1/>Loading<block-text-2/></div>\`);
   
@@ -325,9 +325,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div>Loading<block-child-0/></div>\`);
   
@@ -342,35 +342,35 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = text(ctx['text1']);
+    const b2 = text(ctx['text1']);
-    let b3 = text(ctx['text2']);
+    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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = text(ctx['text1']);
+    const b2 = text(ctx['text1']);
-    let b3 = text(ctx['text2']);
+    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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><block-text-0/><block-text-1/></div>\`);
   

tests/compiler/__snapshots__/svg.test.ts.snap

@@ -1,9 +1,9 @@
 // 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<g block-ns=\\"http://www.w3.org/2000/svg\\"><circle cx=\\"50\\" cy=\\"50\\" r=\\"4\\" stroke=\\"green\\" stroke-width=\\"1\\" fill=\\"yellow\\"/> </g>\`);
   
@@ -14,9 +14,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<svg block-ns=\\"http://www.w3.org/2000/svg\\" width=\\"100px\\" height=\\"90px\\"><circle cx=\\"50\\" cy=\\"50\\" r=\\"4\\" stroke=\\"green\\" stroke-width=\\"1\\" fill=\\"yellow\\"/> </svg>\`);
   
@@ -27,9 +27,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<svg block-ns=\\"http://www.w3.org/2000/svg\\"><g/></svg>\`);
   
@@ -40,9 +40,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<svg block-ns=\\"http://www.w3.org/2000/svg\\"><svg/></svg>\`);
   
@@ -52,10 +52,73 @@ exports[`properly support svg namespace to svg tags added even if already in svg
 }"
 `;
 
-exports[`properly support svg svg namespace added to sub-blocks 1`] = `
+exports[`properly support svg svg creates new block if it is within html -- 2 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
-  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  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 b3;
+    if (ctx['hasPath']) {
+      b3 = block3();
+    }
+    const b2 = block2([], [b3]);
+    return block1([], [b2]);
+  }
+}"
+`;
+
+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, comment } = bdom;
+  
+  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, 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, comment } = bdom;
+  
+  let block1 = createBlock(\`<path block-ns=\\"http://www.w3.org/2000/svg\\"/>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    return block1();
+  }
+}"
+`;
+
+exports[`properly support svg svg namespace added to sub-blocks 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<svg block-ns=\\"http://www.w3.org/2000/svg\\"><block-child-0/></svg>\`);
   let block2 = createBlock(\`<path block-ns=\\"http://www.w3.org/2000/svg\\"/>\`);

tests/compiler/__snapshots__/t_debug_log.test.ts.snap

@@ -1,9 +1,9 @@
 // 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   let block2 = createBlock(\`<span>hey</span>\`);
@@ -21,9 +21,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<p>coucou</p>\`);
   
@@ -35,25 +35,24 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
-  let { getTemplate } = helpers;
+  const callTemplate_1 = app.getTemplate(\`sub\`);
-  const callTemplate_1 = 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue } = helpers;
   
   let block1 = createBlock(\`<div/>\`);

tests/compiler/__snapshots__/t_esc.test.ts.snap

@@ -1,9 +1,9 @@
 // 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><p><block-text-0/></p><p><block-text-1/></p><p><block-text-2/></p><p><block-text-3/></p><p><block-text-4/></p></div>\`);
   
@@ -19,9 +19,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<span><block-text-0/></span>\`);
   
@@ -33,9 +33,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<span><block-text-0/></span>\`);
   
@@ -47,9 +47,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { withDefault } = helpers;
   
   let block1 = createBlock(\`<span><block-text-0/></span>\`);
@@ -62,9 +62,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { withDefault } = helpers;
   
   let block1 = createBlock(\`<span><block-text-0/></span>\`);
@@ -77,29 +77,29 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = text(ctx['v1']);
+    const b2 = text(ctx['v1']);
-    let b3 = text(\`:\`);
+    const b3 = text(\`:\`);
-    let b4 = text(ctx['v2']);
+    const b4 = text(ctx['v2']);
-    let b5 = text(\`:\`);
+    const b5 = text(\`:\`);
-    let b6 = text(ctx['v3']);
+    const b6 = text(ctx['v3']);
-    let b7 = text(\`:\`);
+    const b7 = text(\`:\`);
-    let b8 = text(ctx['v4']);
+    const b8 = text(ctx['v4']);
-    let b9 = text(\`:\`);
+    const b9 = text(\`:\`);
-    let b10 = text(ctx['v5']);
+    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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<span><block-text-0/></span>\`);
   
@@ -111,9 +111,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, LazyValue } = helpers;
   
   let block1 = createBlock(\`<div><block-text-0/></div>\`);
@@ -126,7 +126,32 @@ exports[`t-esc t-esc is escaped 1`] = `
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1
-    ctx[\`var\`] = new LazyValue(value1, ctx, node);
+    ctx[\`var\`] = new LazyValue(value1, ctx, this, node, key);
+    let txt1 = ctx['var'];
+    return block1([txt1]);
+  }
+}"
+`;
+
+exports[`t-esc t-esc with the 0 number 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return text(ctx['var']);
+  }
+}"
+`;
+
+exports[`t-esc t-esc with the 0 number, in a p 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  let block1 = createBlock(\`<p><block-text-0/></p>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
     let txt1 = ctx['var'];
     return block1([txt1]);
   }
@@ -134,9 +159,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<span><block-text-0/></span>\`);
   
@@ -148,11 +173,11 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
-  let { isBoundary, zero, getTemplate } = helpers;
+  let { isBoundary, zero } = helpers;
-  const callTemplate_1 = getTemplate(\`sub\`);
+  const callTemplate_1 = app.getTemplate(\`sub\`);
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   let block2 = createBlock(\`<p>escaped</p>\`);
@@ -160,18 +185,18 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { zero } = helpers;
   
   let block1 = createBlock(\`<span><block-text-0/></span>\`);
@@ -183,10 +208,21 @@ exports[`t-esc t-esc=0 is escaped 2`] = `
 }"
 `;
 
-exports[`t-esc variable 1`] = `
+exports[`t-esc top level t-esc with undefined 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
-  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return text(ctx['var']);
+  }
+}"
+`;
+
+exports[`t-esc variable 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<span><block-text-0/></span>\`);
   

tests/compiler/__snapshots__/t_foreach.test.ts.snap

@@ -1,31 +1,31 @@
 // 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { prepareList, withKey } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { prepareList, withKey } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
@@ -33,98 +33,98 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { prepareList, withKey } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   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'];
+      const key1 = ctx['item'];
-      let b4 = text(\` [\`);
+      const b4 = text(\` [\`);
-      let b5 = text(ctx['item_index']);
+      const b5 = text(ctx['item_index']);
-      let b6 = text(\`: \`);
+      const b6 = text(\`: \`);
-      let b7 = text(ctx['item']);
+      const b7 = text(ctx['item']);
-      let b8 = text(\` \`);
+      const b8 = text(\` \`);
-      let b9 = text(ctx['item_value']);
+      const b9 = text(ctx['item_value']);
-      let b10 = text(\`] \`);
+      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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { prepareList, withKey } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   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'];
+      const key1 = ctx['item_index'];
-      let b4 = text(\` [\`);
+      const b4 = text(\` [\`);
-      let b5 = text(ctx['item_index']);
+      const b5 = text(ctx['item_index']);
-      let b6 = text(\`: \`);
+      const b6 = text(\`: \`);
-      let b7 = text(ctx['item']);
+      const b7 = text(ctx['item']);
-      let b8 = text(\` \`);
+      const b8 = text(\` \`);
-      let b9 = text(ctx['item_value']);
+      const b9 = text(ctx['item_value']);
-      let b10 = text(\`] \`);
+      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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { prepareList, withKey } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   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']) {
@@ -138,46 +138,46 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { prepareList, withKey } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   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 { text, createBlock, list, multi, html, toggler, 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);
@@ -186,9 +186,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { prepareList, withKey } = helpers;
   
   let block3 = createBlock(\`<span>a<block-text-0/></span>\`);
@@ -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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
-  let { prepareList, isBoundary, withDefault, setContextValue, getTemplate, withKey } = helpers;
+  let { prepareList, isBoundary, withDefault, setContextValue, withKey } = helpers;
-  const callTemplate_1 = getTemplate(\`sub\`);
+  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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = text(\` [\`);
+    const b2 = text(\` [\`);
-    let b3 = text(ctx['a']);
+    const b3 = text(ctx['a']);
-    let b4 = text(\`] [\`);
+    const b4 = text(\`] [\`);
-    let b5 = text(ctx['b']);
+    const b5 = text(ctx['b']);
-    let b6 = text(\`] [\`);
+    const b6 = text(\`] [\`);
-    let b7 = text(ctx['c']);
+    const b7 = text(ctx['c']);
-    let b8 = text(\`] \`);
+    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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
-  let { prepareList, getTemplate, withKey } = helpers;
+  let { prepareList, withKey } = helpers;
-  const callTemplate_1 = getTemplate(\`sub\`);
+  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'];
@@ -330,75 +330,75 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue } = helpers;
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1
     setContextValue(ctx, \\"c\\", 'x'+'_'+ctx['a']+'_'+ctx['b']);
-    let b2 = text(\` [\`);
+    const b2 = text(\` [\`);
-    let b3 = text(ctx['a']);
+    const b3 = text(ctx['a']);
-    let b4 = text(\`] [\`);
+    const b4 = text(\`] [\`);
-    let b5 = text(ctx['b']);
+    const b5 = text(ctx['b']);
-    let b6 = text(\`] [\`);
+    const b6 = text(\`] [\`);
-    let b7 = text(ctx['c']);
+    const b7 = text(ctx['c']);
-    let b8 = text(\`] \`);
+    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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { prepareList, withKey } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   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'];
+        const key2 = ctx['letter'];
-        let b5 = text(\` [\`);
+        const b5 = text(\` [\`);
-        let b6 = text(ctx['number']);
+        const b6 = text(ctx['number']);
-        let b7 = text(ctx['letter']);
+        const b7 = text(ctx['letter']);
-        let b8 = text(\`] \`);
+        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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { prepareList, withKey } = helpers;
   
   let block3 = createBlock(\`<span><block-text-0/></span>\`);
   
   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;
@@ -412,9 +412,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { prepareList, withKey } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
@@ -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;
@@ -433,16 +433,16 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { prepareList, withKey } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
@@ -450,22 +450,22 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { prepareList, withKey } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
@@ -473,24 +473,24 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { prepareList, withKey } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
@@ -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;
+      const key1 = ctx['item'].id;
-      let memo1 = [ctx['item'].x]
+      const memo1 = [ctx['item'].x];
-      let vnode1 = cache[key1];
+      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]);
   }
 }"

tests/compiler/__snapshots__/t_if.test.ts.snap

@@ -1,9 +1,9 @@
 // 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block2 = createBlock(\`<div>foo</div>\`);
   
@@ -19,9 +19,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block3 = createBlock(\`<span>yip</span>\`);
   let block4 = createBlock(\`<div>yip</div>\`);
@@ -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();
+      const b3 = block3();
-      let b4 = block4();
+      const b4 = block4();
       b2 = multi([b3, b4]);
     }
     return multi([b2]);
@@ -39,9 +39,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
     let b2,b3,b4,b5;
@@ -60,9 +60,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><block-child-0/><block-child-1/><block-child-2/><block-child-3/></div>\`);
   
@@ -83,9 +83,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><span>begin</span><block-child-0/><block-child-1/><span>end</span></div>\`);
   
@@ -102,9 +102,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><span>begin</span><block-child-0/><block-child-1/><span>end</span></div>\`);
   
@@ -121,9 +121,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<span><block-child-0/></span>\`);
   
@@ -138,9 +138,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><block-child-0/><block-child-1/><block-child-2/><block-child-3/><block-child-4/><block-child-5/><block-child-6/><block-child-7/></div>\`);
   
@@ -176,9 +176,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   let block3 = createBlock(\`<span>yip</span>\`);
@@ -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();
+      const b3 = block3();
-      let b4 = block4();
+      const b4 = block4();
       b2 = multi([b3, b4]);
     }
     return block1([], [b2]);
@@ -197,9 +197,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><block-child-0/><block-text-0/></div>\`);
   let block3 = createBlock(\`<p>1</p>\`);
@@ -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();
+      const b3 = block3();
-      let b4 = block4();
+      const b4 = block4();
       b2 = multi([b3, b4]);
     }
     let txt1 = ctx['text'];
@@ -219,9 +219,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
     let b2;
@@ -234,9 +234,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
     let b2,b3;
@@ -251,9 +251,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><block-child-0/><block-child-1/></div>\`);
   
@@ -270,9 +270,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><block-child-0/><block-child-1/></div>\`);
   
@@ -289,9 +289,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
@@ -306,9 +306,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block4 = createBlock(\`<span>a</span>\`);
   let block5 = createBlock(\`<span>b</span>\`);
@@ -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();
+      const b4 = block4();
-      let b5 = block5();
+      const b5 = block5();
       b3 = multi([b4, b5]);
     }
     return multi([b2, b3]);
@@ -328,9 +328,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
@@ -345,9 +345,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   let block2 = createBlock(\`<span>1<block-child-0/></span>\`);
@@ -367,9 +367,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
     let b2,b3;
@@ -383,9 +383,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
     let b2,b3;
@@ -402,9 +402,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
@@ -423,9 +423,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
@@ -446,9 +446,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/><block-child-1/></div>\`);
@@ -472,9 +472,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
     let b2,b3;
@@ -490,9 +490,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><block-child-0/><block-child-1/></div>\`);
   
@@ -510,9 +510,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><block-child-0/><block-child-1/></div>\`);
   let block2 = createBlock(\`<span><block-text-0/></span>\`);
@@ -526,8 +526,8 @@ exports[`t-if two t-ifs next to each other 1`] = `
       b2 = block2([txt1]);
     }
     if (ctx['condition']) {
-      let b4 = block4();
+      const b4 = block4();
-      let b5 = block5();
+      const b5 = block5();
       b3 = multi([b4, b5]);
     }
     return block1([], [b2, b3]);

tests/compiler/__snapshots__/t_key.test.ts.snap

@@ -1,9 +1,9 @@
 // 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><block-text-0/></div>\`);
   
@@ -16,9 +16,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><block-text-0/></div>\`);
   
@@ -31,9 +31,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><block-text-0/></div>\`);
   
@@ -46,9 +46,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { prepareList, withKey } = helpers;
   
   let block1 = createBlock(\`<ul><block-child-0/></ul>\`);
@@ -56,23 +56,23 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><block-child-0/><block-child-1/></div>\`);
   let block2 = createBlock(\`<span/>\`);
@@ -91,9 +91,9 @@ 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = createBlock(\`<div><h1/></div>\`);
   

tests/compiler/__snapshots__/t_out.test.ts.snap

@@ -1,24 +1,24 @@
 // 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { safeOutput } = helpers;
   
   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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { safeOutput } = helpers;
   
   return function template(ctx, node, key = \\"\\") {
@@ -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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
-  let { isBoundary, zero, getTemplate } = helpers;
+  let { isBoundary, zero } = helpers;
-  const callTemplate_1 = getTemplate(\`sub\`);
+  const callTemplate_1 = app.getTemplate(\`sub\`);
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   let block2 = createBlock(\`<span>coucou</span>\`);
@@ -40,51 +40,66 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { zero } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/><div>Greeter</div><block-child-1/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = ctx[zero];
+    const b2 = ctx[zero];
-    let b3 = 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { safeOutput } = helpers;
   
   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, 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
-  let { isBoundary, zero, getTemplate } = helpers;
+  let { isBoundary, zero } = helpers;
-  const callTemplate_1 = getTemplate(\`_basic-callee\`);
+  const callTemplate_1 = app.getTemplate(\`_basic-callee\`);
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   let block2 = createBlock(\`<div>zero</div>\`);
@@ -92,48 +107,48 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { zero } = helpers;
   
   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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { safeOutput } = helpers;
   
   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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, LazyValue, safeOutput } = helpers;
   
   let block1 = createBlock(\`<div><span><block-child-0/></span></div>\`);
@@ -146,140 +161,140 @@ exports[`t-out t-out bdom 1`] = `
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1
-    ctx[\`var\`] = new LazyValue(value1, ctx, node);
+    ctx[\`var\`] = new LazyValue(value1, ctx, this, node, key);
-    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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { safeOutput } = helpers;
   
   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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { safeOutput } = helpers;
   
   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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { safeOutput } = helpers;
   
   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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
-  let { safeOutput, withDefault } = helpers;
+  let { safeOutput } = helpers;
   
   let block1 = createBlock(\`<span><block-child-0/></span>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b3 = text(\`nope\`);
+    const b3 = text(\`nope\`);
-    let b2 = withDefault(safeOutput(ctx['var']), b3);
+    const b2 = 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
-  let { safeOutput, withDefault } = helpers;
+  let { safeOutput } = helpers;
   
   let block1 = createBlock(\`<span><block-child-0/></span>\`);
   let block3 = createBlock(\`<div>nope</div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b3 = block3();
+    const b3 = block3();
-    let b2 = withDefault(safeOutput(ctx['var']), b3);
+    const b2 = 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { safeOutput } = helpers;
   
   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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { safeOutput } = helpers;
   
   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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { safeOutput } = helpers;
   
   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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, LazyValue, safeOutput } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/><block-child-1/></div>\`);
@@ -295,12 +310,12 @@ exports[`t-out t-out switch markup on bdom 1`] = `
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1
     let b3,b5;
-    ctx[\`bdom\`] = new LazyValue(value1, ctx, node);
+    ctx[\`bdom\`] = new LazyValue(value1, ctx, this, node, key);
     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]);
@@ -309,24 +324,24 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { safeOutput } = helpers;
   
   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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { safeOutput } = helpers;
   
   return function template(ctx, node, key = \\"\\") {
@@ -336,54 +351,93 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { safeOutput } = helpers;
   
   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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { safeOutput } = helpers;
   
   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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { safeOutput } = helpers;
   
   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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { safeOutput } = helpers;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return safeOutput(ctx['var']);
+  }
+}"
+`;
+
+exports[`t-out t-out with the 0 number 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { safeOutput } = helpers;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return safeOutput(ctx['var']);
+  }
+}"
+`;
+
+exports[`t-out t-out with the 0 number, in a p 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { safeOutput } = helpers;
+  
+  let block1 = createBlock(\`<p><block-child-0/></p>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = safeOutput(ctx['var']);
+    return block1([], [b2]);
+  }
+}"
+`;
+
+exports[`t-out top level t-out with undefined 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { safeOutput } = helpers;
   
   return function template(ctx, node, key = \\"\\") {
@@ -393,45 +447,75 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { safeOutput } = helpers;
   
   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, 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, 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { safeOutput } = helpers;
   
   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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { safeOutput } = helpers;
   
   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]);
   }
 }"

tests/compiler/__snapshots__/t_ref.test.ts.snap

@@ -1,78 +1,98 @@
 // 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { singleRefSetter } = helpers;
   
   let block1 = createBlock(\`<div><span block-ref=\\"0\\"/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const refs = ctx.__owl__.refs;
+    const refs = this.__owl__.refs;
     const v1 = ctx['id'];
-    let ref1 = (el) => refs[\`myspan\${v1}\`] = el;
+    let ref1 = singleRefSetter(refs, \`myspan\${v1}\`);
+    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, comment } = bdom;
+  let { singleRefSetter } = helpers;
+  
+  let block1 = createBlock(\`<div><span block-ref=\\"0\\"/></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    const refs = this.__owl__.refs;
+    const v1 = ctx['id'];
+    let ref1 = singleRefSetter(refs, \`myspan\${v1}\`);
     return block1([ref1]);
   }
 }"
 `;
 
 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { singleRefSetter } = helpers;
   
   let block1 = createBlock(\`<div><span block-ref=\\"0\\"/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const refs = ctx.__owl__.refs;
+    const refs = this.__owl__.refs;
-    const ref1 = (el) => refs[\`myspan\`] = el;
+    const ref1 = singleRefSetter(refs, \`myspan\`);
     return block1([ref1]);
   }
 }"
 `;
 
 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
-  let { getTemplate } = helpers;
+  const callTemplate_1 = app.getTemplate(\`sub\`);
-  const callTemplate_1 = 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { singleRefSetter } = helpers;
   
   let block1 = createBlock(\`<div>1<span block-ref=\\"0\\"/>2</div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const refs = ctx.__owl__.refs;
+    const refs = this.__owl__.refs;
-    const ref1 = (el) => refs[\`name\`] = el;
+    const ref1 = singleRefSetter(refs, \`name\`);
     return block1([ref1]);
   }
 }"
 `;
 
 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { singleRefSetter } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   let block2 = createBlock(\`<span block-ref=\\"0\\"/>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const refs = ctx.__owl__.refs;
+    const refs = this.__owl__.refs;
-    const ref1 = (el) => refs[\`name\`] = el;
+    const ref1 = singleRefSetter(refs, \`name\`);
     let b2;
     if (ctx['condition']) {
       b2 = block2([ref1]);
@@ -83,45 +103,46 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
-  let { prepareList, withKey } = helpers;
+  let { prepareList, singleRefSetter, withKey } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   let block3 = createBlock(\`<div block-ref=\\"0\\"><block-text-1/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const refs = ctx.__owl__.refs;
+    const refs = this.__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 = singleRefSetter(refs, (v1));
       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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { singleRefSetter } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/><p block-ref=\\"0\\"/></div>\`);
   let block2 = createBlock(\`<span block-ref=\\"0\\"/>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const refs = ctx.__owl__.refs;
+    const refs = this.__owl__.refs;
-    const ref1 = (el) => refs[\`name\`] = el;
+    const ref1 = singleRefSetter(refs, \`name\`);
-    const ref2 = (el) => refs[\`p\`] = el;
+    const ref2 = singleRefSetter(refs, \`p\`);
     let b2;
     if (ctx['condition']) {
       b2 = block2([ref1]);

tests/compiler/__snapshots__/t_set.test.ts.snap

@@ -1,9 +1,9 @@
 // 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue } = helpers;
   
   let block1 = createBlock(\`<div><block-text-0/></div>\`);
@@ -19,9 +19,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue } = helpers;
   
   let block1 = createBlock(\`<div><block-text-0/></div>\`);
@@ -37,9 +37,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue } = helpers;
   
   return function template(ctx, node, key = \\"\\") {
@@ -52,9 +52,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue } = helpers;
   
   let block1 = createBlock(\`<div><block-text-0/></div>\`);
@@ -70,9 +70,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue } = helpers;
   
   let block1 = createBlock(\`<div><block-text-0/></div>\`);
@@ -88,9 +88,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, LazyValue } = helpers;
   
   function value1(ctx, node, key = \\"\\") {
@@ -106,16 +106,16 @@ exports[`t-set set from body literal (with t-if/t-else 1`] = `
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1
-    ctx[\`value\`] = new LazyValue(value1, ctx, node);
+    ctx[\`value\`] = new LazyValue(value1, ctx, this, node, key);
     return text(ctx['value']);
   }
 }"
 `;
 
 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue } = helpers;
   
   return function template(ctx, node, key = \\"\\") {
@@ -128,9 +128,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, LazyValue } = helpers;
   
   let block1 = createBlock(\`<div><block-text-0/></div>\`);
@@ -142,7 +142,7 @@ exports[`t-set set from body lookup 1`] = `
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1
-    ctx[\`stuff\`] = new LazyValue(value1, ctx, node);
+    ctx[\`stuff\`] = new LazyValue(value1, ctx, this, node, key);
     let txt1 = ctx['stuff'];
     return block1([txt1]);
   }
@@ -150,9 +150,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue } = helpers;
   
   let block1 = createBlock(\`<div><block-text-0/></div>\`);
@@ -168,9 +168,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
@@ -189,9 +189,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue, LazyValue, safeOutput } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
@@ -206,20 +206,20 @@ exports[`t-set t-set body is evaluated immediately 1`] = `
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1
     setContextValue(ctx, \\"v1\\", 'before');
-    ctx[\`v2\`] = new LazyValue(value1, ctx, node);
+    ctx[\`v2\`] = new LazyValue(value1, ctx, this, node, key);
     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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
-  let { isBoundary, withDefault, setContextValue, getTemplate } = helpers;
+  let { isBoundary, withDefault, setContextValue } = helpers;
-  const callTemplate_1 = getTemplate(\`sub\`);
+  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]);
   }
@@ -236,9 +236,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue } = helpers;
   
   let block1 = createBlock(\`<div><block-text-0/><block-text-1/></div>\`);
@@ -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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
-  let { isBoundary, withDefault, setContextValue, getTemplate } = helpers;
+  let { isBoundary, withDefault, setContextValue } = helpers;
-  const callTemplate_1 = getTemplate(\`sub\`);
+  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]);
@@ -280,9 +280,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue } = helpers;
   
   let block1 = createBlock(\`<div><block-text-0/><block-text-1/></div>\`);
@@ -299,9 +299,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue } = helpers;
   
   let block1 = createBlock(\`<div><block-text-0/></div>\`);
@@ -317,9 +317,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue } = helpers;
   
   let block1 = createBlock(\`<div><block-text-0/><block-text-1/></div>\`);
@@ -336,9 +336,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue, prepareList, withKey } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/><p>EndLoop: <block-text-0/></p></div>\`);
@@ -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]);
   }
@@ -366,9 +366,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue, prepareList, withKey } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/><p>EndLoop: <block-text-0/></p></div>\`);
@@ -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]);
   }
@@ -396,9 +396,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue, prepareList, withKey } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/><p>EndLoop: <block-text-0/></p></div>\`);
@@ -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]);
   }
@@ -426,9 +426,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue, prepareList, withKey } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
@@ -439,39 +439,39 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, LazyValue } = helpers;
   
   let block1 = createBlock(\`<div><block-text-0/></div>\`);
   
   function value1(ctx, node, key = \\"\\") {
-    let b3 = text(ctx['beep']);
+    const b3 = text(ctx['beep']);
-    let b4 = text(\` boop\`);
+    const b4 = text(\` boop\`);
     return multi([b3, b4]);
   }
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1
-    ctx[\`setvar\`] = new LazyValue(value1, ctx, node);
+    ctx[\`setvar\`] = new LazyValue(value1, ctx, this, node, key);
     let txt1 = ctx['setvar'];
     return block1([txt1]);
   }
@@ -479,9 +479,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue, LazyValue, safeOutput } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
@@ -497,19 +497,19 @@ exports[`t-set t-set with t-value (falsy) and body 1`] = `
     ctx[isBoundary] = 1
     setContextValue(ctx, \\"v3\\", false);
     setContextValue(ctx, \\"v1\\", 'before');
-    ctx[\`v2\`] = withDefault(ctx['v3'], new LazyValue(value1, ctx, node));
+    ctx[\`v2\`] = withDefault(ctx['v3'], new LazyValue(value1, ctx, this, node, key));
     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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue, LazyValue, safeOutput } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
@@ -525,22 +525,45 @@ exports[`t-set t-set with t-value (truthy) and body 1`] = `
     ctx[isBoundary] = 1
     setContextValue(ctx, \\"v3\\", 'Truthy');
     setContextValue(ctx, \\"v1\\", 'before');
-    ctx[\`v2\`] = withDefault(ctx['v3'], new LazyValue(value1, ctx, node));
+    ctx[\`v2\`] = withDefault(ctx['v3'], new LazyValue(value1, ctx, this, node, key));
     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`] = `
+exports[`t-set t-set, multiple t-ifs, and a specific configuration 1`] = `
-"function anonymous(bdom, helpers
+"function anonymous(app, bdom, helpers
 ) {
-  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue } = helpers;
   
-  let block1 = createBlock(\`<div><block-child-0/><block-child-0/><block-text-0/></div>\`);
+  let block1 = createBlock(\`<p><div><span>First div</span></div><div><block-child-0/></div></p>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    ctx[isBoundary] = 1
+    let b2;
+    if (ctx['flag']) {
+      setContextValue(ctx, \\"bouh\\", 2);
+    }
+    if (!ctx['flag']) {
+      b2 = text(\`Second\`);
+    }
+    return block1([], [b2]);
+  }
+}"
+`;
+
+exports[`t-set t-set, t-if, and mix of expression/body lookup, 1 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  let { isBoundary, withDefault, setContextValue } = helpers;
+  
+  let block1 = createBlock(\`<div><block-text-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
@@ -557,12 +580,12 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue } = helpers;
   
-  let block1 = createBlock(\`<div><block-child-0/><block-child-0/><block-text-0/></div>\`);
+  let block1 = createBlock(\`<div><block-text-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
@@ -579,9 +602,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue } = helpers;
   
   return function template(ctx, node, key = \\"\\") {
@@ -600,9 +623,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, LazyValue } = helpers;
   
   let block1 = createBlock(\`<div><block-text-0/></div>\`);
@@ -615,7 +638,7 @@ exports[`t-set value priority (with non text body 1`] = `
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1
-    ctx[\`value\`] = withDefault(1, new LazyValue(value1, ctx, node));
+    ctx[\`value\`] = withDefault(1, new LazyValue(value1, ctx, this, node, key));
     let txt1 = ctx['value'];
     return block1([txt1]);
   }
@@ -623,9 +646,9 @@ 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 { text, createBlock, list, multi, html, toggler, comment } = bdom;
   let { isBoundary, withDefault, setContextValue } = helpers;
   
   let block1 = createBlock(\`<div><block-text-0/></div>\`);

tests/compiler/__snapshots__/t_tag.test.ts.snap

@@ -1,119 +1,119 @@
 // 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 { text, createBlock, list, multi, html, toggler, 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 { text, createBlock, list, multi, html, toggler, 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 { text, createBlock, list, multi, html, toggler, 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 { text, createBlock, list, multi, html, toggler, 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 { text, createBlock, list, multi, html, toggler, 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 { text, createBlock, list, multi, html, toggler, 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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block1 = tag => createBlock(\`<\${tag || 't'}><block-child-0/></\${tag || 't'}>\`);
   let block2 = tag => createBlock(\`<\${tag || 't'}>baz</\${tag || 't'}>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let tag1 = ctx['outer'];
+    const tag1 = ctx['outer'];
-    let tag2 = ctx['inner'];
+    const tag2 = ctx['inner'];
-    let b2 = toggler(tag2, block2(tag2)());
+    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;
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
   
   let block2 = tag => createBlock(\`<\${tag || 't'}>bar</\${tag || 't'}>\`);
   let block3 = tag => createBlock(\`<\${tag || 't'}>baz</\${tag || 't'}>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let tag1 = ctx['brother'];
+    const tag1 = ctx['brother'];
-    let b2 = toggler(tag1, block2(tag1)());
+    const b2 = toggler(tag1, block2(tag1)());
-    let tag2 = ctx['brother'];
+    const tag2 = ctx['brother'];
-    let b3 = toggler(tag2, block3(tag2)());
+    const b3 = toggler(tag2, block3(tag2)());
     return multi([b2, b3]);
   }
 }"