[REL] v2.0.0-beta-7

# 2.0.0-beta-7

- fix: concurrency: do not render delayed fibers when cancelled
- imp: allow duplicate templates if and only if they are the same

.github/workflows/deploy.yml

@@ -5,7 +5,7 @@ name: Node.js CI
 
 on:
   pull_request:
-    branches: [ master, owl-next ]
+    branches: [ master ]
 
 jobs:
   build:

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
-ideas may help:
-
-- try to organize the state/architecture to minimize the number of state updates
-- take advantage of the finer reactivity system. For example, if we have a list
-  of items, with a component for each item, we can write this:
-
-  ```js
-  class Item extends Component {
-      setup() {
-          this.item = useState(this.props.item); // and only use this, not props.item
-      }
-  }
-  ```
-  Doing so will make it that each `Item` component will register itself as an
-  observer of its own item, and will be the only component being rerendered when
-  its item object is updated.
-- use the `Memo` component to wrap some piece of template. `Memo` memoize its
-  content, and only update itself if its props are different (shallow comparison):
-  
-  ```xml
-    <Memo a="state.a" b="state.b"> 
-        <t t-esc="state.a"/>
-        <t t-esc="state.b"/>
-        <t t-esc="state.c"/>
-    </Memo>
-  ```
+Migration code: remove the `shouldUpdate` methods, and it should work as well
+as before.
 
 ### 9. component.el is removed
 
@@ -325,41 +312,6 @@ Documentation:
 - [Mounting a component](doc/reference/app.md#mount-helper)
 
 
-### 12. `t-on` does not work on components any more
-
-In owl 1, it was possible to bind an event listener on a component tag in a
-template:
-
-```xml
-<SomeComponent t-on-some-event="doSomething"/>
-```
-
-This does not work any more.
-
-Rationale: with the support of fragments, there is no longer a canonical html
-element that we can refer. So, this makes it difficult to implement correctly
-and efficiently. Also, we noticed in practice that the event system was an issue
-in some cases, when components need to communicate before they are mounted. In
-those cases, the better solution is to directly use a callback.  Also, another
-conceptual issue with this is that it kind of breaks the component encapsulation.
-The child component kind of leak its own implementation to the outside world.
-
-Migration: a quick fix that may work in some cases is to simply bind the event
-handler on a parent htmlelement. A better way to do it, if possible, is to change
-the component API to accept explicitely a callback as props. 
-
-```xml
-<SomeComponent onSomeEvent="doSomething"/>
-<!-- or alternatively: -->
-<SomeComponent onSomeEvent.bind="doSomething"/>
-```
-
-Note that one of the example above uses the `.bind` suffix, to bind the function
-prop to the component.  Most of the time, binding the function is necessary, and
-using the `.bind` suffix is very helpful in that case.
-
-Documentation: [Binding function props](doc/reference/props.md#binding-function-props)
-
 ### 13. Portal does no longer transfer DOM events
 
 In Owl 1, a Portal component would listen to events emitted on its portalled
@@ -565,15 +517,12 @@ either a fallback when the data is not ready, or the actual component with data
 as props.  If there is no escape, and `AsyncRoot` is needed, please reach out to
 us so we can study this usecase.
 
-### 27. `useSubEnv` only applies to child components
+### 27. `useChildSubEnv` (only applies to child components)
 
-In Owl 1, a call to `useSubEnv` would define a new environment for the children
-AND the component. It now only defines an environment for the children.
-
-Rationale: This was a subtle cause for bugs: some code had to be rrun
-before the call to `useSubEnv`, otherwise it could interfere with the sub environment.
-
-Documentation: [Hooks](doc/reference/hooks.md#usesubenv)
+In Owl, a call to `useSubEnv` would define a new environment for the children
+AND the component. It is very useful, but in some cases, one only need to update
+the children component environment. This can now be done with a new hook:
+[`useChildSubEnv`](doc/reference/hooks.md#usesubenv-and-usechildsubenv)
 
 ### 28. `env` is now frozen
 
@@ -659,10 +608,14 @@ Also, this can easily be done in userspace, by mounting a component in a div.  F
 export async function renderToString(template, context) {
   class C extends Component {
     static template = template;
+    setup () {
+        Object.assign(this, context);
+    }
   }
   const div = document.createElement('div');
   document.body.appendChild(div);
-  const component = await mount(C, div);
+  const app = new App(C);
+  await app.mount(div);
   const result = div.innerHTML;
   app.destroy();
   div.remove();
@@ -670,6 +623,30 @@ export async function renderToString(template, context) {
 }
 ```
 
+The function above works for most cases, but is asynchronous.  An alternative
+function could look like this:
+
+```js
+const { App, blockDom } = owl;
+const app = new App(Component); // act as a template repository
+
+function renderToString(template, context = {}) {
+  app.addTemplate(template, template, { allowDuplicate: true });
+  const templateFn = app.getTemplate(template);
+  const bdom = templateFn(context, {});
+  const div = document.createElement('div')
+  blockDom.mount(bdom, div);
+  return div.innerHTML;
+}
+```
+
+This is a synchronous function, so it will not work with components, but it should
+be useful for most simple templates.
+
+Also note that these two examples do not translate their templates. To do that,
+they need to be modified to pass the proper translate function to the `App`
+configuration.
+
 ### 33. Portal are now defined with `t-portal`
 
 Before Owl 2, one could use the `Portal` component by importing it and using it.
@@ -762,4 +739,28 @@ Rationale: the `browser` object caused more trouble than it was worth. Also, it
 seems like this should be done in user space, not at the framework level.  
 
 Migration: code should just be adapted to either use another browser object,
-or to use native browser function (and then, just mock them directly).
+or to use native browser function (and then, just mock them directly).
+
+## 40. Rendering a component does not necessarily render child components
+
+Before, if one had the following component tree:
+
+```mermaid
+  graph TD;
+      A-->B;
+      A-->C;
+```
+
+when `A` would render, it would also render `B` and `C`. Now, in Owl 2, it will 
+(shallow) compare the before and after props, and `B` or `C` will only be rerendered
+if their props have changed.
+
+Now, the question is what happens if the props have changed, but in a deeper way?
+In that case, Owl will know, because each props are now reactive. So, if some
+inner value read by `B` was changed, then only `B` will be updated.
+
+Rationale: This was just not possible in Owl 1, but it now possible. This is
+due to the rewriteof the underlying rendering engine and the reactivity
+system. The goal is to have a big performance boost in large screen with many
+components: now Owl only rerender what is strictly useful.
+

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)
@@ -110,6 +111,7 @@ 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 +123,5 @@ npm install @odoo/owl
 
 If you want to use a simple `<script>` tag, the last release can be downloaded here:
 
-- [owl-1.4.7](https://github.com/odoo/owl/releases/tag/v1.4.7)
+- [owl-1.4.10](https://github.com/odoo/owl/releases/tag/v1.4.10)
 

doc/learning/tutorial_todoapp.md

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

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:
 

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.
-
-  The `config` object is an object with some of the following keys:
-
-  - **`env (object)`**: if given, this will be the shared `env` given to each component
-  - **`props (object)`**: the props given to the root component
-  - **`dev (boolean, default=false)`**: if `true`, the application is rendered in `dev`
-    mode, which activates some additional checks (in particular, the props validation
-    code is only performed in dev mode)
-  - **`translatableAttributes (string[])`**: a list of additional attributes that should
-    be translated (see [translations](translations.md))
-  - **`translateFn (function)`**: a function that will be called by owl to translate
-    templates (see [translations](translations.md))
-  - **`templates (string | xml document)`**: all the templates that will be used by
-    the components created by the application.
+  an instance), and the optional second argument is a configuration object (see below).
 
 - **`mount(target, options)`**: first argument is an html element, and the optional
   second argument is an object with mounting options (see below). Mount the app
@@ -58,6 +45,23 @@ 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.
+
 ## `mount` helper
 
 Note that there is a `mount` helper to do that in just a line:
@@ -105,3 +109,13 @@ 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/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
-will be added to the parent environment. Note that it will extend, not replace
-the parent environment. And of course, the parent environment will not be
-affected.
+The `useSubEnv` and `useChildSubEnv` hooks take one argument: an object which
+contains some key/value that will be added to the current environment. These hooks
+will create a new env object with the new information:
+
+- `useSubEnv` will assign this new `env` to itself and to all children components
+- `useChildSubEnv` will only assign this new `env` to all children components.
+
+As usual in Owl, [environments](environment.md) created with these two hooks are
+frozen, to prevent unwanted modifications.
+
+Note that both these hooks can be called an arbitrary number of times. The `env`
+will then be updated accordingly.
 
 ### `useExternalListener`
 

doc/reference/props.md

@@ -168,11 +168,15 @@ For each key, a `prop` definition is either a boolean, a constructor, a list of
   - `shape`: if the type was `Object`, then the `shape` key describes the interface of the object. If it is not set, then we only validate the object, not its elements,
   - `validate`: this is a function which should return a boolean to determine if
     the value is valid or not. Useful for custom validation logic.
+  - `optional`: if true, the prop is not mandatory
 
 There is a special `*` prop that means that additional prop are allowed. This is
 sometimes useful for generic components that will propagate some or all their
 props to their child components.
 
+Note that default values cannot be defined for a mandatory props. Doing so will
+result in a prop validation error.
+
 Examples:
 
 ```js
@@ -190,7 +194,8 @@ class ComponentB extends owl.Component {
       element: {type: Object, shape: {id: Boolean, text: String }
     },
    date: Date,
-   combinedVal: [Number, Boolean]
+   combinedVal: [Number, Boolean],
+   optionalProp: { type: Number, optional: true }
   };
 
   ...

doc/reference/reactivity.md

@@ -5,6 +5,8 @@
 - [Overview](#overview)
 - [`useState`](#usestate)
 - [`reactive`](#reactive)
+- [`markRaw`](#markraw)
+- [`toRaw`](#toraw)
 
 ## Overview
 
@@ -23,6 +25,11 @@ To solve this issue, Owl provides two reactivity primitives:
 
 Most of the time, the `useState` hook is the best solution.
 
+Since version 2.0, Owl applies the fine grained reactivity at the component
+level: props are automatically turned into reactive object, so Owl can track
+which part of these props are consumed by each component, and is therefore able
+to only rerender the impacted components.
+
 ## `useState`
 
 Let us start by an example of how `useState` could be used:
@@ -78,3 +85,47 @@ obj2.b = 3; // log 'observer1' and 'observer2'
 
 Obviously, one can use `reactive` on the result of a `useState` if wanted, this
 is the proper way to watch for some state changes.
+
+## `markRaw`
+
+Marks an object so that it is ignored by the reactivity system. This function returns its argument.
+
+```js
+const someObject = markRaw(...);
+const state = useState({
+  a: 1,
+  obj: someObject
+});
+// here, state.obj === someObject
+```
+
+This is useful in some rare cases. For example, some complex and large object such
+that going through the reactivity system may cause a non trivial performance slowdown.
+
+However, use this function with caution: this is an escape hatch from the reactivity
+system, and as such, using it may cause subtle and unintended issues!
+
+## `toRaw`
+
+Given a reactive object, this function returns the underlying, non-reactive,
+corresponding object.
+
+```js
+// in setup
+const state = useState({ value: 1 });
+
+// later:
+const rawState = toRaw(this.state);
+rawState.value = 3; // will NOT be picked up by the reactivity system!!!
+```
+
+Here again, this is useful in some situations where we want to explicitely bypass
+Owl, but using this function means that the responsability of coordinating
+state update is given to the user code, instead of Owl. Subtle bugs may arise!
+
+Also, normal (non-reactive objects) will be directly returned by `toRaw`:
+
+```js
+const obj = { a: 1 };
+console.log(toRaw(obj) === obj); // true
+```

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
-be considered the `default` slot. For example:
+All elements inside the component which are not a named slot will be treated as
+part of the content of the `default` slot. For example:
 
 ```xml
 <div t-name="Parent">
@@ -110,6 +110,7 @@ One can mix default slot and named slots:
     default content
     <t t-set-slot="footer">
       content for footer slot here
+    </t>
   </Child>
 </div>
 ```
@@ -209,30 +210,45 @@ use this `Notebook` component:
 </Notebook>
 ```
 
+Slot params works like normal props, so one can use the `.bind` suffix to
+bind a function if needed.
+
 ## Slot scopes
 
-For other kind of advanced use cases, the content of a slot may depends on some
-specific information specific to the generic component. This is the opposite
-of the slot params.
+For other kinds of advanced use cases, the content of a slot may depends on some
+information specific to the generic component. This is the opposite of the slot
+params.
 
-To solve this kind of problems, one can use the `t-set-scope` directive along
+To solve this kind of problems, one can use the `t-slot-scope` directive along
 with the `t-set-slot`. This defines the name of a variable that can access
 everything given by the child component:
 
 ```xml
-<div>
-    <t t-set-slot="foo" t-set-scope="scope">
+<MyComponent>
+    <t t-set-slot="foo" t-slot-scope="scope">
         content
         <t t-esc="scope.bool"/>
         <t t-esc="scope.num"/>
     </t>
-</div>
+</MyComponent>
 ```
 
 And the child component that includes the slot can provide values like this:
 
 ```xml
-<div>
-    <t t-slot="foo" bool="other_var" num="5">
-</div>
+<t t-slot="foo" bool="other_var" num="5">
 ```
+
+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
 
@@ -674,7 +675,19 @@ This `RootNode` component will then display a live SVG representation of the
 graph described by the `graph` property. Note that there is a recursive structure
 here: the `Node` component uses itself as a subcomponent.
 
-Note that since SVG needs to be handled in a specific way (its namespace needs
-to be properly set), there is a small constraint for Owl components: if an owl
-component is supposed to be a part of an svg graph, then its root node needs to
-be a `g` tag, so Owl can properly set the namespace.
+**Important note:** Owl needs to properly set the namespace for each svg elements.
+Since Owl compile each template separately, it is not able to determine easily
+if a template is supposed to be included in a svg namespace or not. Therefore,
+Owl depends on a heuristic: if a tag is either `svg`, `g` or `path`, then it will
+be considered as svg. In practice, this means that each component or each sub
+templates (included with `t-call`) should have one of these tag as root tag.
+
+## Restrictions
+
+Note that Owl templates forbid the use of tag and or attributes starting with
+the `block-` string. This restriction prevents name collision with the internal
+code of Owl.
+
+```xml
+<div><block-1>this will not be accepted by Owl</block-1></div>
+```

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...
+```

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@odoo/owl",
-  "version": "2.0.0-alpha1",
+  "version": "2.0.0-beta-7",
   "description": "Odoo Web Library (OWL)",
   "main": "dist/owl.cjs.js",
   "browser": "dist/owl.iife.js",

roadmap.md

@@ -1,6 +1,6 @@
 # 🦉 OWL Roadmap 🦉
 
-- Current version: 1.4.7
+- Current version: 1.4.10
 - Status: stable
 
 This roadmap is only an attempt at predicting Owl's future.  Everything may

src/app/app.ts

@@ -1,9 +1,10 @@
-import { Component } from "../component/component";
+import { Component, ComponentConstructor } 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";
+import { validateTarget } from "../utils";
 
 // reimplement dev mode stuff see last change in 0f7a8289a6fb8387c3c1af41c6664b2a8448758f
 
@@ -11,53 +12,62 @@ export interface Env {
   [key: string]: any;
 }
 
-export interface AppConfig extends TemplateSetConfig {
-  env?: Env;
-  props?: any;
+export interface AppConfig<P, E> extends TemplateSetConfig {
+  props?: P;
+  env?: E;
+  test?: boolean;
 }
 
-export const DEV_MSG = `Owl is running in 'dev' mode.
+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/master/doc/reference/config.md#mode for more information.`;
+See https://github.com/odoo/owl/blob/${hash}/doc/reference/app.md#configuration for more information.`;
+};
 
-export class App<T extends typeof Component = any> extends TemplateSet {
-  Root: T;
-  props: any;
-  env: Env;
+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 | null = null;
+  root: ComponentNode<P, E> | null = null;
 
-  constructor(Root: T, config: AppConfig = {}) {
+  constructor(Root: ComponentConstructor<P, E>, config: AppConfig<P, E> = {}) {
     super(config);
     this.Root = Root;
-    if (config.dev) {
-      console.info(DEV_MSG);
+    if (config.test) {
+      this.dev = true;
     }
-    const descrs = Object.getOwnPropertyDescriptors(config.env || {});
-    this.env = Object.freeze(Object.defineProperties({}, descrs));
-    this.props = config.props || {};
+    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<InstanceType<T>> {
-    this.checkTarget(target);
+  mount(target: HTMLElement, options?: MountOptions): Promise<Component<P, E> & InstanceType<T>> {
+    App.validateTarget(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);
+  makeNode(Component: ComponentConstructor, props: any): ComponentNode {
+    return new ComponentNode(Component, props, this, null, null);
   }
 
   mountNode(node: ComponentNode, target: HTMLElement, options?: MountOptions) {
@@ -91,15 +101,20 @@ export class App<T extends typeof Component = any> extends TemplateSet {
 
   destroy() {
     if (this.root) {
+      this.scheduler.flush();
       this.root.destroy();
     }
   }
 }
 
-export async function mount<T extends typeof Component>(
-  C: T,
+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 & MountOptions = {}
-): Promise<InstanceType<T>> {
+  config: AppConfig<P, E> & MountOptions = {}
+): Promise<Component<P, E> & InstanceType<T>> {
   return new App(C, config).mount(target, config);
 }

src/app/template_helpers.ts

@@ -1,7 +1,9 @@
-import { BDom, multi, text, toggler } from "../blockdom";
+import { BDom, multi, text, toggler, createCatcher } 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.
@@ -21,11 +23,11 @@ function callSlot(
   defaultContent?: (ctx: any, node: any, key: string) => BDom
 ): BDom {
   key = key + "__slot_" + name;
-  const slots = (ctx.props && ctx.props.slots) || {};
+  const slots = ctx.props[TARGET].slots || {};
   const { __render, __ctx, __scope } = slots[name] || {};
   const slotScope = Object.create(__ctx || {});
   if (__scope) {
-    slotScope[__scope] = extra || {};
+    slotScope[__scope] = extra;
   }
   const slotBDom = __render ? __render.call(__ctx.__owl__.component, slotScope, parent, key) : null;
   if (defaultContent) {
@@ -135,7 +137,7 @@ export function safeOutput(value: any): ReturnType<typeof toggler> {
   } else if (value instanceof LazyValue) {
     safeKey = `lazy_value`;
     block = value.evaluate();
-  } else if (typeof value === "string") {
+  } else if (value instanceof String || typeof value === "string") {
     safeKey = "string_unsafe";
     block = text(value);
   } else {
@@ -181,7 +183,7 @@ function multiRefSetter(refs: RefMap, name: string): RefSetter {
   };
 }
 
-export const UTILS = {
+export const helpers = {
   withDefault,
   zero: Symbol("zero"),
   isBoundary,
@@ -197,4 +199,5 @@ export const UTILS = {
   LazyValue,
   safeOutput,
   bind,
+  createCatcher,
 };

src/app/template_set.ts

@@ -1,12 +1,13 @@
 import { createBlock, html, list, multi, text, toggler, comment } from "../blockdom";
 import { compile, Template } from "../compiler";
-import { component } from "../component/component_node";
-import { UTILS } from "./template_helpers";
+import { markRaw } from "../reactivity";
+import { Portal } from "../portal";
+import { component, getCurrent } from "../component/component_node";
+import { helpers } from "./template_helpers";
+import { globalTemplates } from "../utils";
 
 const bdom = { text, createBlock, list, multi, html, toggler, component, comment };
 
-export const globalTemplates: { [key: string]: string | Node } = {};
-
 function parseXML(xml: string): Document {
   const parser = new DOMParser();
 
@@ -37,6 +38,22 @@ function parseXML(xml: string): Document {
   return doc;
 }
 
+/**
+ * Returns the helpers object that will be injected in each template closure
+ * function
+ */
+function makeHelpers(getTemplate: (name: string) => Template): any {
+  return Object.assign({}, helpers, {
+    Portal,
+    markRaw,
+    getTemplate,
+    call: (owner: any, subTemplate: string, ctx: any, parent: any, key: any) => {
+      const template = getTemplate(subTemplate);
+      return toggler(subTemplate, template.call(owner, ctx, parent, key));
+    },
+  });
+}
+
 export interface TemplateSetConfig {
   dev?: boolean;
   translatableAttributes?: string[];
@@ -50,13 +67,7 @@ export class TemplateSet {
   templates: { [name: string]: Template } = {};
   translateFn?: (s: string) => string;
   translatableAttributes?: string[];
-  utils: typeof UTILS = Object.assign({}, UTILS, {
-    call: (owner: any, subTemplate: string, ctx: any, parent: any, key: any) => {
-      const template = this.getTemplate(subTemplate);
-      return toggler(subTemplate, template.call(owner, ctx, parent, key));
-    },
-    getTemplate: (name: string, nameSpace?: string) => this.getTemplate(name, nameSpace),
-  });
+  helpers: any;
 
   constructor(config: TemplateSetConfig = {}) {
     this.dev = config.dev || false;
@@ -65,16 +76,23 @@ export class TemplateSet {
     if (config.templates) {
       this.addTemplates(config.templates);
     }
+    this.helpers = makeHelpers(this.getTemplate.bind(this));
   }
 
-  addTemplate(name: string, template: string | Node, options: { allowDuplicate?: boolean } = {}) {
-    if (name in this.rawTemplates && !options.allowDuplicate) {
-      throw new Error(`Template ${name} already defined`);
+  addTemplate(name: string, template: string | Element) {
+    if (name in this.rawTemplates) {
+      const rawTemplate = this.rawTemplates[name];
+      const currentAsString = typeof rawTemplate === "string" ? rawTemplate : rawTemplate.outerHTML;
+      const newAsString = typeof template === "string" ? template : template.outerHTML;
+      if (currentAsString === newAsString) {
+        return;
+      }
+      throw new Error(`Template ${name} already defined with different content`);
     }
     this.rawTemplates[name] = template;
   }
 
-  addTemplates(xml: string | Document, options: { allowDuplicate?: boolean } = {}) {
+  addTemplates(xml: string | Document) {
     if (!xml) {
       // empty string
       return;
@@ -82,52 +100,40 @@ export class TemplateSet {
     xml = xml instanceof Document ? xml : parseXML(xml);
     for (const template of xml.querySelectorAll("[t-name]")) {
       const name = template.getAttribute("t-name")!;
-      template.removeAttribute("t-name");
-      this.addTemplate(name, template, options);
+      this.addTemplate(name, template);
     }
   }
 
-  getTemplate(name: string, nameSpace?: string): Template {
-
+  getTemplate(name: string): Template {
     if (!(name in this.templates)) {
       const rawTemplate = this.rawTemplates[name];
       if (rawTemplate === undefined) {
-        throw new Error(`Missing template: "${name}"`);
+        let extraInfo = "";
+        try {
+          const componentName = getCurrent().component.constructor.name;
+          extraInfo = ` (for component "${componentName}")`;
+        } catch {}
+        throw new Error(`Missing template: "${name}"${extraInfo}`);
       }
-          console.log("getTemplate", nameSpace);
-      const templateFn = this._compileTemplate(name, rawTemplate, nameSpace);
+      const templateFn = 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(bdom, this.helpers);
       this.templates[name] = template;
     }
     return this.templates[name];
   }
 
-  _compileTemplate(name: string, template: string | Node, nameSpace?: string) {
-    console.log("CompileTpm", nameSpace)
+  _compileTemplate(name: string, template: string | Element) {
     return compile(template, {
       name,
       dev: this.dev,
       translateFn: this.translateFn,
       translatableAttributes: this.translatableAttributes,
-      nameSpace: nameSpace,
     });
   }
 }
-
-// -----------------------------------------------------------------------------
-//  xml tag helper
-// -----------------------------------------------------------------------------
-export function xml(...args: Parameters<typeof String.raw>) {
-  const name = `__template__${xml.nextId++}`;
-  const value = String.raw(...args);
-  globalTemplates[name] = value;
-  return name;
-}
-
-xml.nextId = 1;

src/blockdom/attributes.ts

@@ -139,7 +139,8 @@ export function updateClass(this: HTMLElement, val: any, oldVal: any) {
 
 export function makePropSetter(name: string): Setter<HTMLElement> {
   return function setProp(this: HTMLElement, value: any) {
-    (this as any)[name] = value;
+    // support 0, fallback to empty string for other falsy values
+    (this as any)[name] = value === 0 ? 0 : value || "";
   };
 }
 

src/blockdom/block_compiler.ts

@@ -299,12 +299,13 @@ interface BlockCtx {
   locations: IndexedLocation[];
   children: Child[];
   cbRefs: number[];
+  refList: (() => void)[][];
 }
 
 function buildContext(tree: IntermediateTree, ctx?: BlockCtx, fromIdx?: number): BlockCtx {
   if (!ctx) {
     const children = new Array(tree.info.filter((v) => v.type === "child").length);
-    ctx = { collectors: [], locations: [], children, cbRefs: [], refN: tree.refN };
+    ctx = { collectors: [], locations: [], children, cbRefs: [], refN: tree.refN, refList: [] };
     fromIdx = 0;
   }
   if (tree.refN) {
@@ -408,11 +409,11 @@ function updateCtx(ctx: BlockCtx, tree: IntermediateTree) {
         break;
       }
       case "ref":
-        ctx.cbRefs.push(info.idx);
+        const index = ctx.cbRefs.push(info.idx) - 1;
         ctx.locations.push({
           idx: info.idx,
           refIdx: info.refIdx!,
-          setData: setRef,
+          setData: makeRefSetter(index, ctx.refList),
           updateData: NO_OP,
         });
     }
@@ -426,12 +427,21 @@ function buildBlock(template: HTMLElement, ctx: BlockCtx): BlockType {
   let B = createBlockClass(template, ctx);
 
   if (ctx.cbRefs.length) {
-    const refs = ctx.cbRefs;
+    const cbRefs = ctx.cbRefs;
+    const refList = ctx.refList;
+    let cbRefsNumber = cbRefs.length;
     B = class extends B {
+      mount(parent: HTMLElement, afterNode: Node | null) {
+        refList.push(new Array(cbRefsNumber));
+        super.mount(parent, afterNode);
+        for (let cbRef of refList.pop()!) {
+          cbRef();
+        }
+      }
       remove() {
         super.remove();
-        for (let ref of refs) {
-          let fn = (this as any).data[ref];
+        for (let cbRef of cbRefs) {
+          let fn = (this as any).data[cbRef];
           fn(null);
         }
       }
@@ -476,12 +486,12 @@ function createBlockClass(template: HTMLElement, ctx: BlockCtx): BlockClass {
   const nodeInsertBefore = nodeProto.insertBefore;
   const elementRemove = elementProto.remove;
 
-  return class Block {
+  class Block {
     el: HTMLElement | undefined;
-    refs: Node[] | undefined;
-    data: any[] | undefined;
     parentEl?: HTMLElement | undefined;
+    data: any[] | undefined;
     children?: (VNode | undefined)[];
+    refs: Node[] | undefined;
 
     constructor(data?: any[]) {
       this.data = data;
@@ -502,46 +512,62 @@ function createBlockClass(template: HTMLElement, ctx: BlockCtx): BlockClass {
       nodeInsertBefore.call(this.parentEl, this.el!, target);
     }
 
+    toString() {
+      const div = document.createElement("div");
+      this.mount(div, null);
+      return div.innerHTML;
+    }
+
     mount(parent: HTMLElement, afterNode: Node | null) {
-      const el = nodeCloneNode.call(template, true);
+      const el = nodeCloneNode.call(template, true) as HTMLElement;
       nodeInsertBefore.call(parent, el, afterNode);
-      if (isDynamic) {
-        // collecting references
-        const refs: Node[] = new Array(refN);
-        this.refs = refs;
-        refs[0] = el;
-        for (let i = 0; i < colN; i++) {
-          const w = collectors[i];
-          refs[w.idx] = w.getVal.call(refs[w.prevIdx]);
-        }
+      this.el = el;
+      this.parentEl = parent;
+    }
+    patch(other: Block, withBeforeRemove: boolean) {}
+  }
 
-        // applying data to all update points
-        if (locN) {
-          const data = this.data!;
-          for (let i = 0; i < locN; i++) {
-            const loc = locations[i];
-            loc.setData.call(refs[loc.refIdx], data[i]);
-          }
-        }
+  if (isDynamic) {
+    Block.prototype.mount = function mount(parent: HTMLElement, afterNode: Node | null) {
+      const el = nodeCloneNode.call(template, true);
+      // collecting references
+      const refs: Node[] = new Array(refN);
+      this.refs = refs;
+      refs[0] = el;
+      for (let i = 0; i < colN; i++) {
+        const w = collectors[i];
+        refs[w.idx] = w.getVal.call(refs[w.prevIdx]);
+      }
 
-        // preparing all children
-        if (childN) {
-          const children = this.children;
-          for (let i = 0; i < childN; i++) {
-            const child = children![i];
-            if (child) {
-              const loc = childrenLocs[i];
-              const afterNode = loc.afterRefIdx ? refs[loc.afterRefIdx] : null;
-              child.isOnlyChild = loc.isOnlyChild;
-              child.mount(refs[loc.parentRefIdx] as any, afterNode);
-            }
+      // applying data to all update points
+      if (locN) {
+        const data = this.data!;
+        for (let i = 0; i < locN; i++) {
+          const loc = locations[i];
+          loc.setData.call(refs[loc.refIdx], data[i]);
+        }
+      }
+
+      nodeInsertBefore.call(parent, el, afterNode);
+
+      // preparing all children
+      if (childN) {
+        const children = this.children;
+        for (let i = 0; i < childN; i++) {
+          const child = children![i];
+          if (child) {
+            const loc = childrenLocs[i];
+            const afterNode = loc.afterRefIdx ? refs[loc.afterRefIdx] : null;
+            child.isOnlyChild = loc.isOnlyChild;
+            child.mount(refs[loc.parentRefIdx] as any, afterNode);
           }
         }
       }
       this.el = el as HTMLElement;
       this.parentEl = parent;
-    }
-    patch(other: Block, withBeforeRemove: boolean) {
+    };
+
+    Block.prototype.patch = function patch(other: Block, withBeforeRemove: boolean) {
       if (this === other) {
         return;
       }
@@ -586,19 +612,17 @@ function createBlockClass(template: HTMLElement, ctx: BlockCtx): BlockClass {
           }
         }
       }
-    }
-    toString() {
-      const div = document.createElement("div");
-      this.mount(div, null);
-      return div.innerHTML;
-    }
-  };
+    };
+  }
+  return Block;
 }
 
 function setText(this: Text, value: any) {
   characterDataSetData.call(this, toText(value));
 }
 
-function setRef(this: HTMLElement, fn: any) {
-  fn(this);
+function makeRefSetter(index: number, refs: (() => void)[][]): Setter<HTMLElement> {
+  return function setRef(this: HTMLElement, fn: any) {
+    refs[refs.length - 1][index] = () => fn(this);
+  };
 }

src/blockdom/event_catcher.ts

@@ -0,0 +1,89 @@
+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 {
+  let setupFns: any[] = [];
+  let removeFns: any[] = [];
+  for (let name in eventsSpec) {
+    let index = eventsSpec[name];
+    let { setup, remove } = createEventHandler(name);
+    setupFns[index] = setup;
+    removeFns[index] = remove;
+  }
+  let n = setupFns.length;
+
+  class VCatcher {
+    child: VNode;
+    handlers: any[];
+
+    parentEl?: HTMLElement | undefined;
+    afterNode: Node | null = null;
+
+    constructor(child: VNode, handlers: any[]) {
+      this.child = child;
+      this.handlers = handlers;
+    }
+
+    mount(parent: HTMLElement, afterNode: Node | null) {
+      this.parentEl = parent;
+      this.afterNode = afterNode;
+      this.child.mount(parent, afterNode);
+      for (let i = 0; i < n; i++) {
+        let origFn = this.handlers[i][0];
+        const self = this;
+        this.handlers[i][0] = function (ev: any) {
+          const target = ev.target;
+          let currentNode: any = self.child.firstNode();
+          const afterNode = self.afterNode;
+          while (currentNode !== afterNode) {
+            if (currentNode.contains(target)) {
+              return origFn.call(this, ev);
+            }
+            currentNode = currentNode.nextSibling;
+          }
+        };
+        setupFns[i].call(parent, this.handlers[i]);
+      }
+    }
+
+    moveBefore(other: VCatcher | null, afterNode: Node | null) {
+      this.afterNode = null;
+      this.child.moveBefore(other ? other.child : null, afterNode);
+    }
+
+    patch(other: VCatcher, withBeforeRemove: boolean) {
+      if (this === other) {
+        return;
+      }
+      this.handlers = other.handlers;
+      this.child.patch(other.child, withBeforeRemove);
+    }
+
+    beforeRemove() {
+      this.child.beforeRemove();
+    }
+
+    remove() {
+      for (let i = 0; i < n; i++) {
+        removeFns[i].call(this.parentEl!);
+      }
+      this.child.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/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 {
@@ -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/blockdom/html.ts

@@ -61,6 +61,7 @@ class VHtml {
       // remove current content
       this.remove();
       this.content = content;
+      this.html = other.html;
     }
   }
 

src/blockdom/index.ts

@@ -6,6 +6,7 @@ export { list } from "./list";
 export { multi } from "./multi";
 export { text, comment } from "./text";
 export { html } from "./html";
+export { createCatcher } from "./event_catcher";
 
 export interface VNode<T = any> {
   mount(parent: HTMLElement, afterNode: Node | null): void;

src/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;
   }
 
@@ -65,7 +65,7 @@ class VComment extends VSimpleNode {
   patch() {}
 }
 
-export function text(str: string): VNode<VText> {
+export function text(str: string | String): VNode<VText> {
   return new VText(str);
 }
 

src/compiler/code_generator.ts

@@ -20,6 +20,8 @@ import {
   ASTTranslation,
   ASTType,
   ASTTPortal,
+  EventHandlers,
+  Attrs,
 } from "./parser";
 
 type BlockType = "block" | "text" | "multi" | "list" | "html" | "comment";
@@ -33,7 +35,6 @@ export interface Config {
 export interface CodeGenOptions extends Config {
   hasSafeContext?: boolean;
   name?: string;
-  nameSpace?: string;
 }
 
 // using a non-html document so that <inner/outer>HTML serializes as XML instead
@@ -129,6 +130,7 @@ interface Context {
   translate: boolean;
   tKeyExpr: string | null;
   nameSpace?: string;
+  tModelSelectedExpr?: string;
 }
 
 function createContext(parentCtx: Context, params?: Partial<Context>) {
@@ -140,6 +142,7 @@ function createContext(parentCtx: Context, params?: Partial<Context>) {
       translate: parentCtx.translate,
       tKeyExpr: null,
       nameSpace: parentCtx.nameSpace,
+      tModelSelectedExpr: parentCtx.tModelSelectedExpr,
     },
     params
   );
@@ -156,9 +159,11 @@ class CodeTarget {
   // maps ref name to [id, expr]
   refInfo: { [name: string]: [string, string] } = {};
   shouldProtectScope: boolean = false;
+  on: EventHandlers | null;
 
-  constructor(name: string) {
+  constructor(name: string, on?: EventHandlers | null) {
     this.name = name;
+    this.on = on || null;
   }
 
   addLine(line: string, idx?: number) {
@@ -213,21 +218,28 @@ export class CodeGenerator {
   templateName?: string;
   dev: boolean;
   translateFn: (s: string) => string;
-  translatableAttributes: string[];
+  translatableAttributes: string[] = TRANSLATABLE_ATTRS;
   ast: AST;
-  staticCalls: { id: string; template: string, nameSpace?: string }[] = [];
+  staticDefs: { id: string; expr: string }[] = [];
   helpers: Set<string> = new Set();
-  nameSpace?: string;
 
   constructor(ast: AST, options: CodeGenOptions) {
     this.translateFn = options.translateFn || ((s: string) => s);
-    this.translatableAttributes = options.translatableAttributes || TRANSLATABLE_ATTRS;
+    if (options.translatableAttributes) {
+      const attrs = new Set(TRANSLATABLE_ATTRS);
+      for (let attr of options.translatableAttributes) {
+        if (attr.startsWith("-")) {
+          attrs.delete(attr.slice(1));
+        } else {
+          attrs.add(attr);
+        }
+      }
+      this.translatableAttributes = [...attrs];
+    }
     this.hasSafeContext = options.hasSafeContext || false;
     this.dev = options.dev || false;
     this.ast = ast;
     this.templateName = options.name;
-    this.nameSpace = options.nameSpace;
-    console.log('ThisNS', this.nameSpace)
   }
 
   generateCode(): string {
@@ -242,7 +254,6 @@ export class CodeGenerator {
       isLast: true,
       translate: true,
       tKeyExpr: null,
-      nameSpace: this.nameSpace,
     });
     // define blocks and utility functions
     let mainCode = [
@@ -255,12 +266,8 @@ export class CodeGenerator {
       mainCode.push(`// Template name: "${this.templateName}"`);
     }
 
-    for (let { id, template, nameSpace } of this.staticCalls) {
-      let ns;
-      if (nameSpace) {
-        ns = `, "${nameSpace}"`;
-      }
-      mainCode.push(`const ${id} = getTemplate(${template}${ns});`);
+    for (let { id, expr } of this.staticDefs) {
+      mainCode.push(`const ${id} = ${expr};`);
     }
 
     // define all blocks
@@ -300,20 +307,23 @@ export class CodeGenerator {
     return code;
   }
 
-  compileInNewTarget(prefix: string, ast: AST, ctx: Context): string {
+  compileInNewTarget(prefix: string, ast: AST, ctx: Context, on?: EventHandlers | null): string {
     const name = this.generateId(prefix);
     const initialTarget = this.target;
-    const target = new CodeTarget(name);
+    const target = new CodeTarget(name, on);
     this.targets.push(target);
     this.target = target;
-    const subCtx: Context = createContext(ctx);
-    this.compileAST(ast, subCtx);
+    this.compileAST(ast, createContext(ctx));
     this.target = initialTarget;
     return name;
   }
 
-  addLine(line: string) {
-    this.target.addLine(line);
+  addLine(line: string, idx?: number) {
+    this.target.addLine(line, idx);
+  }
+
+  define(varName: string, expr: string) {
+    this.addLine(`const ${varName} = ${expr};`);
   }
 
   generateId(prefix: string = ""): string {
@@ -365,9 +375,12 @@ export class CodeGenerator {
     }
 
     if (block.isRoot && !ctx.preventRoot) {
+      if (this.target.on) {
+        blockExpr = this.wrapWithEventCatcher(blockExpr, this.target.on);
+      }
       this.addLine(`return ${blockExpr};`);
     } else {
-      this.addLine(`let ${block.varName} = ${blockExpr};`);
+      this.define(block.varName, blockExpr);
     }
   }
 
@@ -396,7 +409,7 @@ export class CodeGenerator {
           if (!mapping.has(tok.varName)) {
             const varId = this.generateId("v");
             mapping.set(tok.varName, varId);
-            this.addLine(`const ${varId} = ${tok.value};`);
+            this.define(varId, tok.value);
           }
           tok.value = mapping.get(tok.varName)!;
         }
@@ -531,46 +544,57 @@ export class CodeGenerator {
 
   compileTDomNode(ast: ASTDomNode, ctx: Context) {
     let { block, forceNewBlock } = ctx;
-    const isNewBlock = !block || forceNewBlock || ast.dynamicTag !== null;
+    const isNewBlock = !block || forceNewBlock || ast.dynamicTag !== null || ast.ns;
     let codeIdx = this.target.code.length;
     if (isNewBlock) {
-      if ((ast.dynamicTag || ctx.tKeyExpr) && ctx.block) {
+      if ((ast.dynamicTag || ctx.tKeyExpr || ast.ns) && ctx.block) {
         this.insertAnchor(ctx.block!);
       }
       block = this.createBlock(block, "block", ctx);
       this.blocks.push(block);
       if (ast.dynamicTag) {
         const tagExpr = this.generateId("tag");
-        this.addLine(`let ${tagExpr} = ${compileExpr(ast.dynamicTag)};`);
+        this.define(tagExpr, compileExpr(ast.dynamicTag));
         block.dynamicTagName = tagExpr;
       }
     }
     // attributes
-    const attrs: { [key: string]: string } = {};
+    const attrs: Attrs = {};
     const nameSpace = ast.ns || ctx.nameSpace;
-    console.log(nameSpace)
     if (nameSpace && isNewBlock) {
       // specific namespace uri
       attrs["block-ns"] = nameSpace;
     }
+
     for (let key in ast.attrs) {
+      let expr, attrName;
       if (key.startsWith("t-attf")) {
-        let expr = interpolate(ast.attrs[key]);
+        expr = interpolate(ast.attrs[key]);
         const idx = block!.insertData(expr, "attr");
-        attrs["block-attribute-" + idx] = key.slice(7);
+
+        attrName = key.slice(7);
+        attrs["block-attribute-" + idx] = attrName;
       } else if (key.startsWith("t-att")) {
-        let expr = compileExpr(ast.attrs[key]);
+        expr = compileExpr(ast.attrs[key]);
         const idx = block!.insertData(expr, "attr");
         if (key === "t-att") {
           attrs[`block-attributes`] = String(idx);
         } else {
-          attrs[`block-attribute-${idx}`] = key.slice(6);
+          attrName = key.slice(6);
+          attrs[`block-attribute-${idx}`] = attrName;
         }
       } else if (this.translatableAttributes.includes(key)) {
         attrs[key] = this.translateFn(ast.attrs[key]);
       } else {
+        expr = `"${ast.attrs[key]}"`;
+        attrName = key;
         attrs[key] = ast.attrs[key];
       }
+
+      if (attrName === "value" && ctx.tModelSelectedExpr) {
+        let selectedId = block!.insertData(`${ctx.tModelSelectedExpr} === ${expr}`, "attr");
+        attrs[`block-attribute-${selectedId}`] = "selected";
+      }
     }
 
     // event handlers
@@ -610,8 +634,10 @@ export class CodeGenerator {
     }
 
     // t-model
+    let tModelSelectedExpr;
     if (ast.model) {
       const {
+        hasDynamicChildren,
         baseExpr,
         expr,
         eventType,
@@ -622,20 +648,25 @@ export class CodeGenerator {
       } = ast.model;
 
       const baseExpression = compileExpr(baseExpr);
-      const id = this.generateId();
-      this.addLine(`const bExpr${id} = ${baseExpression};`);
+      const bExprId = this.generateId("bExpr");
+      this.define(bExprId, baseExpression);
 
       const expression = compileExpr(expr);
+      const exprId = this.generateId("expr");
+      this.define(exprId, expression);
+
+      const fullExpression = `${bExprId}[${exprId}]`;
 
       let idx: number;
       if (specialInitTargetAttr) {
-        idx = block!.insertData(
-          `${baseExpression}[${expression}] === '${attrs[targetAttr]}'`,
-          "attr"
-        );
+        idx = block!.insertData(`${fullExpression} === '${attrs[targetAttr]}'`, "attr");
         attrs[`block-attribute-${idx}`] = specialInitTargetAttr;
+      } else if (hasDynamicChildren) {
+        const bValueId = this.generateId("bValue");
+        tModelSelectedExpr = `${bValueId}`;
+        this.define(tModelSelectedExpr, fullExpression);
       } else {
-        idx = block!.insertData(`${baseExpression}[${expression}]`, "attr");
+        idx = block!.insertData(`${fullExpression}`, "attr");
         attrs[`block-attribute-${idx}`] = targetAttr;
       }
       this.helpers.add("toNumber");
@@ -643,7 +674,7 @@ export class CodeGenerator {
       valueCode = shouldTrim ? `${valueCode}.trim()` : valueCode;
       valueCode = shouldNumberize ? `toNumber(${valueCode})` : valueCode;
 
-      const handler = `[(ev) => { bExpr${id}[${expression}] = ${valueCode}; }]`;
+      const handler = `[(ev) => { ${fullExpression} = ${valueCode}; }]`;
       idx = block!.insertData(handler, "hdlr");
       attrs[`block-handler-${idx}`] = eventType;
     }
@@ -668,6 +699,7 @@ export class CodeGenerator {
           isLast: ctx.isLast && i === children.length - 1,
           tKeyExpr: ctx.tKeyExpr,
           nameSpace,
+          tModelSelectedExpr,
         });
         this.compileAST(child, subCtx);
       }
@@ -682,13 +714,13 @@ export class CodeGenerator {
         const children = block!.children.slice();
         let current = children.shift();
         for (let i = codeIdx; i < code.length; i++) {
-          if (code[i].trimStart().startsWith(`let ${current!.varName} `)) {
-            code[i] = code[i].replace(`let ${current!.varName}`, current!.varName);
+          if (code[i].trimStart().startsWith(`const ${current!.varName} `)) {
+            code[i] = code[i].replace(`const ${current!.varName}`, current!.varName);
             current = children.shift();
             if (!current) break;
           }
         }
-        this.target.addLine(`let ${block!.children.map((c) => c.varName)};`, codeIdx);
+        this.addLine(`let ${block!.children.map((c) => c.varName)};`, codeIdx);
       }
     }
   }
@@ -777,13 +809,13 @@ export class CodeGenerator {
         const children = block!.children.slice();
         let current = children.shift();
         for (let i = codeIdx; i < code.length; i++) {
-          if (code[i].trimStart().startsWith(`let ${current!.varName} `)) {
-            code[i] = code[i].replace(`let ${current!.varName}`, current!.varName);
+          if (code[i].trimStart().startsWith(`const ${current!.varName} `)) {
+            code[i] = code[i].replace(`const ${current!.varName}`, current!.varName);
             current = children.shift();
             if (!current) break;
           }
         }
-        this.target.addLine(`let ${block!.children.map((c) => c.varName)};`, codeIdx);
+        this.addLine(`let ${block!.children.map((c) => c.varName)};`, codeIdx);
       }
 
       // note: this part is duplicated from end of compilemulti:
@@ -806,12 +838,10 @@ export class CodeGenerator {
     const l = `l_block${block.id}`;
     const c = `c_block${block.id}`;
     this.helpers.add("prepareList");
-    this.addLine(
-      `const [${keys}, ${vals}, ${l}, ${c}] = prepareList(${compileExpr(ast.collection)});`
-    );
+    this.define(`[${keys}, ${vals}, ${l}, ${c}]`, `prepareList(${compileExpr(ast.collection)});`);
     // Throw errors on duplicate keys in dev mode
     if (this.dev) {
-      this.addLine(`const keys${block.id} = new Set();`);
+      this.define(`keys${block.id}`, `new Set()`);
     }
     this.addLine(`for (let ${loopVar} = 0; ${loopVar} < ${l}; ${loopVar}++) {`);
     this.target.indentLevel++;
@@ -828,7 +858,7 @@ export class CodeGenerator {
     if (!ast.hasNoValue) {
       this.addLine(`ctx[\`${ast.elem}_value\`] = ${keys}[${loopVar}];`);
     }
-    this.addLine(`let key${this.target.loopLevel} = ${ast.key ? compileExpr(ast.key) : loopVar};`);
+    this.define(`key${this.target.loopLevel}`, ast.key ? compileExpr(ast.key) : loopVar);
     if (this.dev) {
       // Throw error on duplicate keys in dev mode
       this.addLine(
@@ -840,8 +870,8 @@ export class CodeGenerator {
     if (ast.memo) {
       this.target.hasCache = true;
       id = this.generateId();
-      this.addLine(`let memo${id} = ${compileExpr(ast.memo)}`);
-      this.addLine(`let vnode${id} = cache[key${this.target.loopLevel}];`);
+      this.define(`memo${id}`, compileExpr(ast.memo));
+      this.define(`vnode${id}`, `cache[key${this.target.loopLevel}];`);
       this.addLine(`if (vnode${id}) {`);
       this.target.indentLevel++;
       this.addLine(`if (shallowEqual(vnode${id}.memo, memo${id})) {`);
@@ -875,7 +905,7 @@ export class CodeGenerator {
 
   compileTKey(ast: ASTTKey, ctx: Context) {
     const tKeyExpr = this.generateId("tKey_");
-    this.addLine(`const ${tKeyExpr} = ${compileExpr(ast.expr)};`);
+    this.define(tKeyExpr, compileExpr(ast.expr));
     ctx = createContext(ctx, {
       tKeyExpr,
       block: ctx.block,
@@ -921,13 +951,13 @@ export class CodeGenerator {
           const children = block!.children.slice();
           let current = children.shift();
           for (let i = codeIdx; i < code.length; i++) {
-            if (code[i].trimStart().startsWith(`let ${current!.varName} `)) {
-              code[i] = code[i].replace(`let ${current!.varName}`, current!.varName);
+            if (code[i].trimStart().startsWith(`const ${current!.varName} `)) {
+              code[i] = code[i].replace(`const ${current!.varName}`, current!.varName);
               current = children.shift();
               if (!current) break;
             }
           }
-          this.target.addLine(`let ${block!.children.map((c) => c.varName)};`, codeIdx);
+          this.addLine(`let ${block!.children.map((c) => c.varName)};`, codeIdx);
         }
       }
 
@@ -960,7 +990,7 @@ export class CodeGenerator {
     const key = `key + \`${this.generateComponentKey()}\``;
     if (isDynamic) {
       const templateVar = this.generateId("template");
-      this.addLine(`const ${templateVar} = ${subTemplate};`);
+      this.define(templateVar, subTemplate);
       block = this.createBlock(block, "multi", ctx);
       this.helpers.add("call");
       this.insertBlock(`call(this, ${templateVar}, ctx, node, ${key})`, block!, {
@@ -970,7 +1000,7 @@ export class CodeGenerator {
     } else {
       const id = this.generateId(`callTemplate_`);
       this.helpers.add("getTemplate");
-      this.staticCalls.push({ id, template: subTemplate, nameSpace: ctx.nameSpace });
+      this.staticDefs.push({ id, expr: `getTemplate(${subTemplate})` });
       block = this.createBlock(block, "multi", ctx);
       this.insertBlock(`${id}.call(this, ctx, node, ${key})`, block!, {
         ...ctx,
@@ -1028,54 +1058,74 @@ export class CodeGenerator {
     return parts.join("__");
   }
 
+  /**
+   * Formats a prop name and value into a string suitable to be inserted in the
+   * generated code. For example:
+   *
+   * Name              Value            Result
+   * ---------------------------------------------------------
+   * "number"          "state"          "number: ctx['state']"
+   * "something"       ""               "something: undefined"
+   * "some-prop"       "state"          "'some-prop': ctx['state']"
+   * "onClick.bind"    "onClick"        "onClick: bind(ctx, ctx['onClick'])"
+   */
+  formatProp(name: string, value: string): string {
+    value = this.captureExpression(value);
+    if (name.includes(".")) {
+      let [_name, suffix] = name.split(".");
+      if (suffix === "bind") {
+        this.helpers.add("bind");
+        name = _name;
+        value = `bind(ctx, ${value || undefined})`;
+      } else {
+        throw new Error("Invalid prop suffix");
+      }
+    }
+    name = /^[a-z_]+$/i.test(name) ? name : `'${name}'`;
+    return `${name}: ${value || undefined}`;
+  }
+
+  formatPropObject(obj: { [prop: string]: any }): string {
+    const params = [];
+    for (const [n, v] of Object.entries(obj)) {
+      params.push(this.formatProp(n, v));
+    }
+    return params.join(", ");
+  }
+
   compileComponent(ast: ASTComponent, ctx: Context) {
     let { block } = ctx;
-
     // props
+    const hasSlotsProp = "slots" in (ast.props || {});
     const props: string[] = [];
-    let hasSlotsProp = false;
-    for (let propName in ast.props) {
-      let propValue = this.captureExpression(ast.props[propName]) || undefined;
-      if (propName.includes(".")) {
-        let [name, suffix] = propName.split(".");
-        if (suffix === "bind") {
-          this.helpers.add("bind");
-          propName = name;
-          propValue = `bind(ctx, ${propValue})`;
-        } else {
-          throw new Error("Invalid prop suffix");
-        }
-      }
-      propName = /^[a-z_]+$/i.test(propName) ? propName : `'${propName}'`;
-      props.push(`${propName}: ${propValue}`);
-      if (propName === "slots") {
-        hasSlotsProp = true;
-      }
+    const propExpr = this.formatPropObject(ast.props || {});
+    if (propExpr) {
+      props.push(propExpr);
     }
 
     // slots
-    const hasSlot = !!Object.keys(ast.slots).length;
     let slotDef: string = "";
-    if (hasSlot) {
+    if (ast.slots) {
       let ctxStr = "ctx";
       if (this.target.loopLevel || !this.hasSafeContext) {
         ctxStr = this.generateId("ctx");
         this.helpers.add("capture");
-        this.addLine(`const ${ctxStr} = capture(ctx);`);
+        this.define(ctxStr, `capture(ctx)`);
       }
       let slotStr: string[] = [];
       for (let slotName in ast.slots) {
-        const slotAst = ast.slots[slotName].content;
-        const name = this.compileInNewTarget("slot", slotAst, ctx);
-        const params = [`__render: ${name}, __ctx: ${ctxStr}`];
+        const slotAst = ast.slots[slotName];
+        const params = [];
+        if (slotAst.content) {
+          const name = this.compileInNewTarget("slot", slotAst.content, ctx, slotAst.on);
+          params.push(`__render: ${name}, __ctx: ${ctxStr}`);
+        }
         const scope = ast.slots[slotName].scope;
         if (scope) {
           params.push(`__scope: "${scope}"`);
         }
         if (ast.slots[slotName].attrs) {
-          for (const [n, v] of Object.entries(ast.slots[slotName].attrs!)) {
-            params.push(`${n}: ${compileExpr(v) || undefined}`);
-          }
+          params.push(this.formatPropObject(ast.slots[slotName].attrs!));
         }
         const slotInfo = `{${params.join(", ")}}`;
         slotStr.push(`'${slotName}': ${slotInfo}`);
@@ -1084,29 +1134,29 @@ export class CodeGenerator {
     }
 
     if (slotDef && !(ast.dynamicProps || hasSlotsProp)) {
-      props.push(`slots: ${slotDef}`);
+      this.helpers.add("markRaw");
+      props.push(`slots: markRaw(${slotDef})`);
     }
 
     const propStr = `{${props.join(",")}}`;
 
     let propString = propStr;
     if (ast.dynamicProps) {
-      if (!props.length) {
-        propString = `${compileExpr(ast.dynamicProps)}`;
-      } else {
-        propString = `Object.assign({}, ${compileExpr(ast.dynamicProps)}, ${propStr})`;
-      }
+      propString = `Object.assign({}, ${compileExpr(ast.dynamicProps)}${
+        props.length ? ", " + propStr : ""
+      })`;
     }
 
     let propVar: string;
     if ((slotDef && (ast.dynamicProps || hasSlotsProp)) || this.dev) {
       propVar = this.generateId("props");
-      this.addLine(`const ${propVar!} = ${propString}`);
+      this.define(propVar!, propString);
       propString = propVar!;
     }
 
     if (slotDef && (ast.dynamicProps || hasSlotsProp)) {
-      this.addLine(`${propVar!}.slots = Object.assign(${slotDef}, ${propVar!}.slots)`);
+      this.helpers.add("markRaw");
+      this.addLine(`${propVar!}.slots = markRaw(Object.assign(${slotDef}, ${propVar!}.slots))`);
     }
 
     // cmap key
@@ -1114,13 +1164,13 @@ export class CodeGenerator {
     let expr: string;
     if (ast.isDynamic) {
       expr = this.generateId("Comp");
-      this.addLine(`let ${expr} = ${compileExpr(ast.name)};`);
+      this.define(expr, compileExpr(ast.name));
     } else {
       expr = `\`${ast.name}\``;
     }
 
     if (this.dev) {
-      this.addLine(`helpers.validateProps(${expr}, ${propVar!}, ctx)`);
+      this.addLine(`helpers.validateProps(${expr}, ${propVar!}, ctx);`);
     }
 
     if (block && (ctx.forceNewBlock === false || ctx.tKeyExpr)) {
@@ -1137,10 +1187,32 @@ export class CodeGenerator {
     if (ast.isDynamic) {
       blockExpr = `toggler(${expr}, ${blockExpr})`;
     }
+
+    // event handling
+    if (ast.on) {
+      blockExpr = this.wrapWithEventCatcher(blockExpr, ast.on);
+    }
+
     block = this.createBlock(block, "multi", ctx);
     this.insertBlock(blockExpr, block, ctx);
   }
 
+  wrapWithEventCatcher(expr: string, on: EventHandlers): string {
+    this.helpers.add("createCatcher");
+    let name = this.generateId("catcher");
+    let spec: any = {};
+    let handlers: any[] = [];
+    for (let ev in on) {
+      let handlerId = this.generateId("hdlr");
+      let idx = handlers.push(handlerId) - 1;
+      spec[ev] = idx;
+      const handler = this.generateHandlerCode(ev, on[ev]);
+      this.define(handlerId, handler);
+    }
+    this.staticDefs.push({ id: name, expr: `createCatcher(${JSON.stringify(spec)})` });
+    return `${name}(${expr}, [${handlers.join(",")}])`;
+  }
+
   compileTSlot(ast: ASTSlot, ctx: Context) {
     this.helpers.add("callSlot");
     let { block } = ctx;
@@ -1154,27 +1226,24 @@ export class CodeGenerator {
       slotName = "'" + ast.name + "'";
     }
 
-    let scope = null;
-    if (ast.attrs) {
-      const params = [];
-      for (const [n, v] of Object.entries(ast.attrs!)) {
-        params.push(`${n}: ${compileExpr(v) || undefined}`);
-      }
-      scope = `{${params.join(", ")}}`;
-    }
-
+    const scope = ast.attrs ? `{${this.formatPropObject(ast.attrs)}}` : null;
     if (ast.defaultContent) {
       const name = this.compileInNewTarget("defaultContent", ast.defaultContent, ctx);
       blockString = `callSlot(ctx, node, key, ${slotName}, ${dynamic}, ${scope}, ${name})`;
     } else {
       if (dynamic) {
         let name = this.generateId("slot");
-        this.addLine(`const ${name} = ${slotName};`);
-        blockString = `toggler(${name}, callSlot(ctx, node, key, ${name}), ${dynamic}, ${scope})`;
+        this.define(name, slotName);
+        blockString = `toggler(${name}, callSlot(ctx, node, key, ${name}, ${dynamic}, ${scope}))`;
       } else {
         blockString = `callSlot(ctx, node, key, ${slotName}, ${dynamic}, ${scope})`;
       }
     }
+    // event handling
+    if (ast.on) {
+      blockString = this.wrapWithEventCatcher(blockString, ast.on);
+    }
+
     if (block) {
       this.insertAnchor(block);
     }
@@ -1197,7 +1266,7 @@ export class CodeGenerator {
     if (this.target.loopLevel || !this.hasSafeContext) {
       ctxStr = this.generateId("ctx");
       this.helpers.add("capture");
-      this.addLine(`const ${ctxStr} = capture(ctx);`);
+      this.define(ctxStr, `capture(ctx);`);
     }
     const blockString = `component(Portal, {target: ${ast.target},slots: {'default': {__render: ${name}, __ctx: ${ctxStr}}}}, key + \`${key}\`, node, ctx)`;
     if (block) {

src/compiler/index.ts

@@ -8,9 +8,11 @@ export type TemplateFunction = (blocks: any, utils: any) => Template;
 
 interface CompileOptions extends Config {
   name?: string;
-  nameSpace?: string,
 }
-export function compile(template: string | Node, options: CompileOptions = {}): TemplateFunction {
+export function compile(
+  template: string | Element,
+  options: CompileOptions = {}
+): TemplateFunction {
   // parsing
   const ast = parse(template);
 
@@ -21,10 +23,8 @@ export function compile(template: string | Node, options: CompileOptions = {}):
       : !template.includes("t-set") && !template.includes("t-call");
 
   // code generation
-  console.log("compile", options)
   const codeGenerator = new CodeGenerator(ast, { ...options, hasSafeContext });
   const code = codeGenerator.generateCode();
-  console.log(code)
   // template function
   return new Function("bdom, helpers", code) as TemplateFunction;
 }

src/compiler/inline_expressions.ts

@@ -199,24 +199,30 @@ const TOKENIZERS = [
 export function tokenize(expr: string): Token[] {
   const result: Token[] = [];
   let token: boolean | Token = true;
+  let error: any;
+  let current = expr;
 
-  while (token) {
-    expr = expr.trim();
-    if (expr) {
-      for (let tokenizer of TOKENIZERS) {
-        token = tokenizer(expr);
-        if (token) {
-          result.push(token);
-          expr = expr.slice(token.size || token.value.length);
-          break;
+  try {
+    while (token) {
+      current = current.trim();
+      if (current) {
+        for (let tokenizer of TOKENIZERS) {
+          token = tokenizer(current);
+          if (token) {
+            result.push(token);
+            current = current.slice(token.size || token.value.length);
+            break;
+          }
         }
+      } else {
+        token = false;
       }
-    } else {
-      token = false;
     }
+  } catch (e) {
+    error = e; // Silence all errors and throw a generic error below
   }
-  if (expr.length) {
-    throw new Error(`Tokenizer error: could not tokenize "${expr}"`);
+  if (current.length || error) {
+    throw new Error(`Tokenizer error: could not tokenize \`${expr}\``);
   }
   return result;
 }
@@ -329,7 +335,9 @@ 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;
     }
   }

src/compiler/parser.ts

@@ -2,6 +2,9 @@
 // AST Type definition
 // -----------------------------------------------------------------------------
 
+export type EventHandlers = { [eventName: string]: string };
+export type Attrs = { [attrs: string]: string };
+
 export const enum ASTType {
   Text,
   Comment,
@@ -33,23 +36,26 @@ export interface ASTComment {
   value: string;
 }
 
+interface TModelInfo {
+  baseExpr: string;
+  expr: string;
+  targetAttr: string;
+  eventType: "change" | "click" | "input";
+  shouldTrim: boolean;
+  shouldNumberize: boolean;
+  hasDynamicChildren: boolean;
+  specialInitTargetAttr: string | null;
+}
+
 export interface ASTDomNode {
   type: ASTType.DomNode;
   tag: string;
-  dynamicTag: string | null;
-  attrs: { [key: string]: string };
   content: AST[];
+  attrs: Attrs | null;
   ref: string | null;
-  on: { [key: string]: string };
-  model: {
-    baseExpr: string;
-    expr: string;
-    targetAttr: string;
-    specialInitTargetAttr: string | null;
-    eventType: "change" | "click" | "input";
-    shouldTrim: boolean;
-    shouldNumberize: boolean;
-  } | null;
+  on: EventHandlers | null;
+  model: TModelInfo | null;
+  dynamicTag: string | null;
   ns: string | null;
 }
 
@@ -90,13 +96,13 @@ export interface ASTTForEach {
   type: ASTType.TForEach;
   collection: string;
   elem: string;
-  key: string | null;
   body: AST;
   memo: string;
   hasNoFirst: boolean;
   hasNoLast: boolean;
   hasNoIndex: boolean;
   hasNoValue: boolean;
+  key: string | null;
 }
 
 export interface ASTTKey {
@@ -111,19 +117,28 @@ export interface ASTTCall {
   body: AST[] | null;
 }
 
+interface SlotDefinition {
+  content: AST | null;
+  scope: string | null;
+  on: EventHandlers | null;
+  attrs: Attrs | null;
+}
+
 export interface ASTComponent {
   type: ASTType.TComponent;
   name: string;
   isDynamic: boolean;
   dynamicProps: string | null;
-  props: { [name: string]: string };
-  slots: { [name: string]: { content: AST; attrs?: { [key: string]: string }; scope?: string } };
+  on: EventHandlers | null;
+  props: { [name: string]: string } | null;
+  slots: { [name: string]: SlotDefinition } | null;
 }
 
 export interface ASTSlot {
   type: ASTType.TSlot;
   name: string;
-  attrs: { [key: string]: string };
+  attrs: Attrs | null;
+  on: EventHandlers | null;
   defaultContent: AST | null;
 }
 
@@ -177,23 +192,35 @@ export type AST =
 // -----------------------------------------------------------------------------
 // Parser
 // -----------------------------------------------------------------------------
-interface ParsingContext {
-  inPreTag: boolean;
-  inSVG: boolean;
-}
+const cache: WeakMap<Element, AST> = new WeakMap();
 
-export function parse(xml: string | Node): AST {
-  const node = xml instanceof Element ? xml : (parseXML(`<t>${xml}</t>`).firstChild! as Element);
-  normalizeXML(node);
-  const ctx = { inPreTag: false, inSVG: false };
-  const ast = parseNode(node, ctx);
+export function parse(xml: string | Element): AST {
+  if (typeof xml === "string") {
+    const elem = parseXML(`<t>${xml}</t>`).firstChild as Element;
+    return _parse(elem);
+  }
+  let ast = cache.get(xml);
   if (!ast) {
-    return { type: ASTType.Text, value: "" };
+    // we clone here the xml to prevent modifying it in place
+    ast = _parse(xml.cloneNode(true) as Element);
+    cache.set(xml, ast);
   }
   return ast;
 }
 
-function parseNode(node: ChildNode, ctx: ParsingContext): AST | null {
+function _parse(xml: Element): AST {
+  normalizeXML(xml);
+  const ctx = { inPreTag: false, inSVG: false };
+  return parseNode(xml, ctx) || { type: ASTType.Text, value: "" };
+}
+
+interface ParsingContext {
+  tModelInfo?: TModelInfo | null;
+  inPreTag: boolean;
+  inSVG: boolean;
+}
+
+function parseNode(node: Node, ctx: ParsingContext): AST | null {
   if (!(node instanceof Element)) {
     return parseTextCommentNode(node, ctx);
   }
@@ -233,7 +260,7 @@ function parseTNode(node: Element, ctx: ParsingContext): AST | null {
 const lineBreakRE = /[\r\n]/;
 const whitespaceRE = /\s+/g;
 
-function parseTextCommentNode(node: ChildNode, ctx: ParsingContext): AST | null {
+function parseTextCommentNode(node: Node, ctx: ParsingContext): AST | null {
   if (node.nodeType === Node.TEXT_NODE) {
     let value = node.textContent || "";
     if (!ctx.inPreTag) {
@@ -281,6 +308,8 @@ function parseTDebugLog(node: Element, ctx: ParsingContext): AST | null {
 const hasDotAtTheEnd = /\.[\w_]+\s*$/;
 const hasBracketsAtTheEnd = /\[[^\[]+\]\s*$/;
 
+const ROOT_SVG_TAGS = new Set(["svg", "g", "path"]);
+
 function parseDOMNode(node: Element, ctx: ParsingContext): AST | null {
   const { tagName } = node;
   const dynamicTag = node.getAttribute("t-tag");
@@ -288,22 +317,23 @@ function parseDOMNode(node: Element, ctx: ParsingContext): AST | null {
   if (tagName === "t" && !dynamicTag) {
     return null;
   }
+  if (tagName.startsWith("block-")) {
+    throw new Error(`Invalid tag name: '${tagName}'`);
+  }
   ctx = Object.assign({}, ctx);
   if (tagName === "pre") {
     ctx.inPreTag = true;
   }
-  const shouldAddSVGNS = tagName === "svg" || (tagName === "g" && !ctx.inSVG);
+  const shouldAddSVGNS = ROOT_SVG_TAGS.has(tagName) && !ctx.inSVG;
   ctx.inSVG = ctx.inSVG || shouldAddSVGNS;
   const ns = shouldAddSVGNS ? "http://www.w3.org/2000/svg" : null;
   const ref = node.getAttribute("t-ref");
   node.removeAttribute("t-ref");
 
-  const children = parseChildren(node, ctx);
-
   const nodeAttrsNames = node.getAttributeNames();
-  const attrs: ASTDomNode["attrs"] = {};
-  const on: ASTDomNode["on"] = {};
-  let model: ASTDomNode["model"] = null;
+  let attrs: ASTDomNode["attrs"] = null;
+  let on: EventHandlers | null = null;
+  let model: TModelInfo | null = null;
 
   for (let attr of nodeAttrsNames) {
     const value = node.getAttribute(attr)!;
@@ -311,6 +341,7 @@ function parseDOMNode(node: Element, ctx: ParsingContext): AST | null {
       if (attr === "t-on") {
         throw new Error("Missing event name with t-on directive");
       }
+      on = on || {};
       on[attr.slice(5)] = value;
     } else if (attr.startsWith("t-model")) {
       if (!["input", "select", "textarea"].includes(tagName)) {
@@ -348,16 +379,31 @@ function parseDOMNode(node: Element, ctx: ParsingContext): AST | null {
         targetAttr: isCheckboxInput ? "checked" : "value",
         specialInitTargetAttr: isRadioInput ? "checked" : null,
         eventType,
+        hasDynamicChildren: false,
         shouldTrim: hasTrimMod && (isOtherInput || isTextarea),
         shouldNumberize: hasNumberMod && (isOtherInput || isTextarea),
       };
-    } else {
+      if (isSelect) {
+        // don't pollute the original ctx
+        ctx = Object.assign({}, ctx);
+        ctx.tModelInfo = model;
+      }
+    } else if (attr.startsWith("block-")) {
+      throw new Error(`Invalid attribute: '${attr}'`);
+    } else if (attr !== "t-name") {
       if (attr.startsWith("t-") && !attr.startsWith("t-att")) {
         throw new Error(`Unknown QWeb directive: '${attr}'`);
       }
+      const tModel = ctx.tModelInfo;
+      if (tModel && ["t-att-value", "t-attf-value"].includes(attr)) {
+        tModel.hasDynamicChildren = true;
+      }
+      attrs = attrs || {};
       attrs[attr] = value;
     }
   }
+
+  const children = parseChildren(node, ctx);
   return {
     type: ASTType.DomNode,
     tag: tagName,
@@ -523,7 +569,7 @@ function parseTCall(node: Element, ctx: ParsingContext): AST | null {
     if (ast && ast.type === ASTType.TComponent) {
       return {
         ...ast,
-        slots: { default: { content: tcall } },
+        slots: { default: { content: tcall, scope: null, on: null, attrs: null } },
       };
     }
   }
@@ -619,7 +665,6 @@ function parseTSetNode(node: Element, ctx: ParsingContext): AST | null {
 
 // Error messages when trying to use an unsupported directive on a component
 const directiveErrorMap = new Map([
-  ["t-on", "t-on is no longer supported on components. Consider passing a callback in props."],
   [
     "t-ref",
     "t-ref is no longer supported on components. Consider exposing only the public part of the component's API through a callback prop.",
@@ -651,18 +696,28 @@ function parseComponent(node: Element, ctx: ParsingContext): AST | null {
   const dynamicProps = node.getAttribute("t-props");
   node.removeAttribute("t-props");
 
-  const props: ASTComponent["props"] = {};
+  const defaultSlotScope = node.getAttribute("t-slot-scope");
+  node.removeAttribute("t-slot-scope");
+  let on: ASTComponent["on"] = null;
+
+  let props: ASTComponent["props"] = null;
   for (let name of node.getAttributeNames()) {
     const value = node.getAttribute(name)!;
     if (name.startsWith("t-")) {
-      const message = directiveErrorMap.get(name.split("-").slice(0, 2).join("-"));
-      throw new Error(message || `unsupported directive on Component: ${name}`);
+      if (name.startsWith("t-on-")) {
+        on = on || {};
+        on[name.slice(5)] = value;
+      } else {
+        const message = directiveErrorMap.get(name.split("-").slice(0, 2).join("-"));
+        throw new Error(message || `unsupported directive on Component: ${name}`);
+      }
     } else {
+      props = props || {};
       props[name] = value;
     }
   }
 
-  const slots: ASTComponent["slots"] = {};
+  let slots: ASTComponent["slots"] | null = null;
   if (node.hasChildNodes()) {
     const clone = <Element>node.cloneNode(true);
 
@@ -694,31 +749,34 @@ function parseComponent(node: Element, ctx: ParsingContext): AST | null {
       slotNode.removeAttribute("t-set-slot");
       slotNode.remove();
       const slotAst = parseNode(slotNode, ctx);
-      if (slotAst) {
-        const slotInfo: any = { content: slotAst };
-        const attrs: { [key: string]: string } = {};
-        for (let attributeName of slotNode.getAttributeNames()) {
-          const value = slotNode.getAttribute(attributeName)!;
-          if (attributeName === "t-slot-scope") {
-            slotInfo.scope = value;
-            continue;
-          }
+      let on: SlotDefinition["on"] = null;
+      let attrs: Attrs | null = null;
+      let scope: string | null = null;
+      for (let attributeName of slotNode.getAttributeNames()) {
+        const value = slotNode.getAttribute(attributeName)!;
+        if (attributeName === "t-slot-scope") {
+          scope = value;
+          continue;
+        } else if (attributeName.startsWith("t-on-")) {
+          on = on || {};
+          on[attributeName.slice(5)] = value;
+        } else {
+          attrs = attrs || {};
           attrs[attributeName] = value;
         }
-        if (Object.keys(attrs).length) {
-          slotInfo.attrs = attrs;
-        }
-        slots[name] = slotInfo;
       }
+      slots = slots || {};
+      slots[name] = { content: slotAst, on, attrs, scope };
     }
 
     // default slot
     const defaultContent = parseChildNodes(clone, ctx);
     if (defaultContent) {
-      slots.default = { content: defaultContent };
+      slots = slots || {};
+      slots.default = { content: defaultContent, on, attrs: null, scope: defaultSlotScope };
     }
   }
-  return { type: ASTType.TComponent, name, isDynamic, dynamicProps, props, slots };
+  return { type: ASTType.TComponent, name, isDynamic, dynamicProps, props, slots, on };
 }
 
 // -----------------------------------------------------------------------------
@@ -731,15 +789,23 @@ function parseTSlot(node: Element, ctx: ParsingContext): AST | null {
   }
   const name = node.getAttribute("t-slot")!;
   node.removeAttribute("t-slot");
-  const attrs: { [key: string]: string } = {};
+  let attrs: Attrs | null = null;
+  let on: ASTComponent["on"] = null;
   for (let attributeName of node.getAttributeNames()) {
     const value = node.getAttribute(attributeName)!;
-    attrs[attributeName] = value;
+    if (attributeName.startsWith("t-on-")) {
+      on = on || {};
+      on[attributeName.slice(5)] = value;
+    } else {
+      attrs = attrs || {};
+      attrs[attributeName] = value;
+    }
   }
   return {
     type: ASTType.TSlot,
     name,
     attrs,
+    on,
     defaultContent: parseChildNodes(node, ctx),
   };
 }
@@ -786,7 +852,7 @@ function parseTPortal(node: Element, ctx: ParsingContext): AST | null {
 /**
  * Parse all the child nodes of a given node and return a list of ast elements
  */
-function parseChildren(node: Node, ctx: ParsingContext): AST[] {
+function parseChildren(node: Element, ctx: ParsingContext): AST[] {
   const children: AST[] = [];
   for (let child of node.childNodes) {
     const childAst = parseNode(child, ctx);
@@ -805,7 +871,7 @@ function parseChildren(node: Node, ctx: ParsingContext): AST[] {
  * Parse all the child nodes of a given node and return an ast if possible.
  * In the case there are multiple children, they are wrapped in a astmulti.
  */
-function parseChildNodes(node: Node, ctx: ParsingContext): AST | null {
+function parseChildNodes(node: Element, ctx: ParsingContext): AST | null {
   const children = parseChildren(node, ctx);
   switch (children.length) {
     case 0:

src/component/component.ts

@@ -4,9 +4,25 @@ import type { ComponentNode } from "./component_node";
 //  Component Class
 // -----------------------------------------------------------------------------
 
+type Props = { [key: string]: any };
+
+interface StaticComponentProperties {
+  template: string;
+  defaultProps?: any;
+  props?: any;
+}
+
+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 +36,7 @@ export class Component<Props = any, Env = any> {
 
   setup() {}
 
-  render() {
-    this.__owl__.render();
+  render(deep: boolean = false) {
+    this.__owl__.render(deep === true);
   }
 }

src/component/component_node.ts

@@ -1,21 +1,26 @@
 import type { App, Env } from "../app/app";
 import { BDom, VNode } from "../blockdom";
-import { Component } from "./component";
 import {
-  Fiber,
-  makeChildFiber,
-  makeRootFiber,
-  MountFiber,
-  MountOptions,
-  RootFiber,
-} from "./fibers";
-import { handleError, fibersInError } from "./error_handling";
+  clearReactivesForCallback,
+  getSubscriptions,
+  NonReactive,
+  Reactive,
+  reactive,
+  TARGET,
+} from "../reactivity";
+import { batched, Callback } from "../utils";
+import { Component, ComponentConstructor } from "./component";
+import { fibersInError, handleError } from "./error_handling";
+import { Fiber, makeChildFiber, makeRootFiber, MountFiber, MountOptions } from "./fibers";
 import { applyDefaultProps } from "./props_validation";
 import { STATUS } from "./status";
 
 let currentNode: ComponentNode | null = null;
 
-export function getCurrent(): ComponentNode | null {
+export function getCurrent(): ComponentNode {
+  if (!currentNode) {
+    throw new Error("No active component (a hook function should only be called in 'setup')");
+  }
   return currentNode;
 }
 
@@ -23,23 +28,59 @@ export function useComponent(): Component {
   return currentNode!.component;
 }
 
-export function component(
-  name: string | typeof Component,
-  props: any,
+// -----------------------------------------------------------------------------
+// Integration with reactivity system (useState)
+// -----------------------------------------------------------------------------
+
+const batchedRenderFunctions = new WeakMap<ComponentNode, Callback>();
+/**
+ * Creates a reactive object that will be observed by the current component.
+ * Reading data from the returned object (eg during rendering) will cause the
+ * component to subscribe to that data and be rerendered when it changes.
+ *
+ * @param state the state to observe
+ * @returns a reactive object that will cause the component to re-render on
+ *  relevant changes
+ * @see reactive
+ */
+export function useState<T extends object>(state: T): Reactive<T> | NonReactive<T> {
+  const node = getCurrent();
+  let render = batchedRenderFunctions.get(node)!;
+  if (!render) {
+    render = batched(node.render.bind(node, false));
+    batchedRenderFunctions.set(node, render);
+    // manual implementation of onWillDestroy to break cyclic dependency
+    node.willDestroy.push(clearReactivesForCallback.bind(null, render));
+  }
+  return reactive(state, render);
+}
+
+// -----------------------------------------------------------------------------
+// component function (used in compiled template code)
+// -----------------------------------------------------------------------------
+type Props = { [key: string]: any };
+
+function arePropsDifferent(props1: Props, props2: Props): boolean {
+  for (let k in props1) {
+    if (props1[k] !== props2[k]) {
+      return true;
+    }
+  }
+  return Object.keys(props1).length !== Object.keys(props2).length;
+}
+
+export function component<P extends object>(
+  name: string | ComponentConstructor<P>,
+  props: P,
   key: string,
   ctx: ComponentNode,
   parent: any
-): ComponentNode {
+): ComponentNode<P> {
   let node: any = ctx.children[key];
   let isDynamic = typeof name !== "string";
 
-  if (node) {
-    if (node.status < STATUS.MOUNTED) {
-      node.destroy();
-      node = undefined;
-    } else if (node.status === STATUS.DESTROYED) {
-      node = undefined;
-    }
+  if (node && node.status === STATUS.DESTROYED) {
+    node = undefined;
   }
   if (isDynamic && node && node.component.constructor !== name) {
     node = undefined;
@@ -47,7 +88,16 @@ export function component(
 
   const parentFiber = ctx.fiber!;
   if (node) {
-    node.updateAndRender(props, parentFiber);
+    let shouldRender = node.forceNextRender;
+    if (shouldRender) {
+      node.forceNextRender = false;
+    } else {
+      const currentProps = node.component.props[TARGET];
+      shouldRender = parentFiber.deep || arePropsDifferent(currentProps, props);
+    }
+    if (shouldRender) {
+      node.updateAndRender(props, parentFiber);
+    }
   } else {
     // new component
     let C;
@@ -59,30 +109,29 @@ export function component(
         throw new Error(`Cannot find the definition of component "${name}"`);
       }
     }
-    node = new ComponentNode(C, props, ctx.app, ctx);
+    node = new ComponentNode(C, props, ctx.app, ctx, key);
     ctx.children[key] = node;
-
-    const fiber = makeChildFiber(node, parentFiber);
-    node.initiateRender(fiber);
+    node.initiateRender(new Fiber(node, parentFiber));
   }
+  parentFiber.childrenMap[key] = node;
   return node;
 }
 
 // -----------------------------------------------------------------------------
-//  Component VNode
+//  Component VNode class
 // -----------------------------------------------------------------------------
 
 type LifecycleHook = Function;
 
-export class ComponentNode<T extends typeof Component = typeof Component>
-  implements VNode<ComponentNode>
-{
+export class ComponentNode<P extends object = any, E = any> implements VNode<ComponentNode<P, E>> {
   el?: HTMLElement | Text | undefined;
   app: App;
   fiber: Fiber | null = null;
-  component: InstanceType<T>;
+  component: Component<P, E>;
   bdom: BDom | null = null;
   status: STATUS = STATUS.NEW;
+  forceNextRender: boolean = false;
+  parentKey: string | null;
 
   renderFn: Function;
   parent: ComponentNode | null;
@@ -99,17 +148,26 @@ 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.parentKey = parentKey;
     this.level = parent ? parent.level + 1 : 0;
     applyDefaultProps(props, C);
     const env = (parent && parent.childEnv) || app.env;
     this.childEnv = env;
+    props = useState(props);
     this.component = new C(props, env, this) as any;
     this.renderFn = app.getTemplate(C.template).bind(this.component, this.component, this);
     this.component.setup();
+    currentNode = null;
   }
 
   mountComponent(target: any, options?: MountOptions) {
@@ -131,26 +189,35 @@ export class ComponentNode<T extends typeof Component = typeof Component>
       return;
     }
     if (this.status === STATUS.NEW && this.fiber === fiber) {
-      this._render(fiber);
+      fiber.render();
     }
   }
 
-  async render() {
+  async render(deep: boolean) {
     let current = this.fiber;
-    if (current && current.root!.locked) {
+    if (current && (current.root!.locked || (current as any).bdom === true)) {
       await Promise.resolve();
       // situation may have changed after the microtask tick
       current = this.fiber;
     }
-    if (current && !current.bdom && !fibersInError.has(current)) {
-      return;
-    }
-    if (!this.bdom && !current) {
+    if (current) {
+      if (!current.bdom && !fibersInError.has(current)) {
+        if (deep) {
+          // we want the render from this point on to be with deep=true
+          current.deep = deep;
+        }
+        return;
+      }
+      // if current rendering was with deep=true, we want this one to be the same
+      deep = deep || current.deep;
+    } else if (!this.bdom) {
       return;
     }
 
     const fiber = makeRootFiber(this);
+    fiber.deep = deep;
     this.fiber = fiber;
+
     this.app.scheduler.addFiber(fiber);
     await Promise.resolve();
     if (this.status === STATUS.DESTROYED) {
@@ -168,16 +235,7 @@ export class ComponentNode<T extends typeof Component = typeof Component>
     //   embedded in a rendering coming from above, so the fiber will be rendered
     //   in the next microtick anyway, so we should not render it again.
     if (this.fiber === fiber && (current || !fiber.parent)) {
-      this._render(fiber);
-    }
-  }
-
-  _render(fiber: Fiber | RootFiber) {
-    try {
-      fiber.bdom = this.renderFn();
-      fiber.root!.counter--;
-    } catch (e) {
-      handleError({ node: this, error: e });
+      fiber.render();
     }
   }
 
@@ -199,8 +257,14 @@ export class ComponentNode<T extends typeof Component = typeof Component>
     for (let child of Object.values(this.children)) {
       child._destroy();
     }
-    for (let cb of this.willDestroy) {
-      cb.call(component);
+    if (this.willDestroy.length) {
+      try {
+        for (let cb of this.willDestroy) {
+          cb.call(component);
+        }
+      } catch (e) {
+        handleError({ error: e, node: this });
+      }
     }
     this.status = STATUS.DESTROYED;
   }
@@ -211,13 +275,17 @@ export class ComponentNode<T extends typeof Component = typeof Component>
     this.fiber = fiber;
     const component = this.component;
     applyDefaultProps(props, component.constructor as any);
+
+    currentNode = this;
+    props = useState(props);
+    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);
+    fiber.render();
     const parentRoot = parentFiber.root!;
     if (this.willPatch.length) {
       parentRoot.willPatch.push(fiber);
@@ -267,6 +335,7 @@ export class ComponentNode<T extends typeof Component = typeof Component>
     bdom.mount(parent, anchor);
     this.status = STATUS.MOUNTED;
     this.fiber!.appliedToDom = true;
+    this.children = this.fiber!.childrenMap;
     this.fiber = null;
   }
 
@@ -275,11 +344,17 @@ export class ComponentNode<T extends typeof Component = typeof Component>
   }
 
   patch() {
-    const hasChildren = Object.keys(this.children).length > 0;
-    this.bdom!.patch(this!.fiber!.bdom!, hasChildren);
-    if (hasChildren) {
-      this.cleanOutdatedChildren();
+    if (this.fiber && this.fiber.parent) {
+      // we only patch here renderings coming from above. renderings initiated
+      // by the component will be patched independently in the appropriate
+      // fiber.complete
+      this._patch();
     }
+  }
+  _patch() {
+    const hasChildren = Object.keys(this.children).length > 0;
+    this.children = this.fiber!.childrenMap;
+    this.bdom!.patch(this!.fiber!.bdom!, hasChildren);
     this.fiber!.appliedToDom = true;
     this.fiber = null;
   }
@@ -292,17 +367,15 @@ export class ComponentNode<T extends typeof Component = typeof Component>
     this.bdom!.remove();
   }
 
-  cleanOutdatedChildren() {
-    const children = this.children;
-    for (const key in children) {
-      const node = children[key];
-      const status = node.status;
-      if (status !== STATUS.MOUNTED) {
-        delete children[key];
-        if (status !== STATUS.DESTROYED) {
-          node.destroy();
-        }
-      }
-    }
+  // ---------------------------------------------------------------------------
+  // Some debug helpers
+  // ---------------------------------------------------------------------------
+  get name(): string {
+    return this.component.constructor.name;
+  }
+
+  get subscriptions(): ReturnType<typeof getSubscriptions> {
+    const render = batchedRenderFunctions.get(this);
+    return render ? getSubscriptions(render) : [];
   }
 }

src/component/error_handling.ts

@@ -5,7 +5,7 @@ import type { Fiber } from "./fibers";
 export const fibersInError: WeakMap<Fiber, any> = new WeakMap();
 export const nodeErrorHandlers: WeakMap<ComponentNode, ((error: any) => void)[]> = new WeakMap();
 
-function _handleError(node: ComponentNode | null, error: any, isFirstRound = false): boolean {
+function _handleError(node: ComponentNode | null, error: any): boolean {
   if (!node) {
     return false;
   }
@@ -16,22 +16,19 @@ function _handleError(node: ComponentNode | null, error: any, isFirstRound = fal
 
   const errorHandlers = nodeErrorHandlers.get(node);
   if (errorHandlers) {
-    let stopped = false;
+    let handled = false;
     // execute in the opposite order
     for (let i = errorHandlers.length - 1; i >= 0; i--) {
       try {
         errorHandlers[i](error);
-        stopped = true;
+        handled = true;
         break;
       } catch (e) {
         error = e;
       }
     }
 
-    if (stopped) {
-      if (isFirstRound && fiber && fiber.node.fiber) {
-        fiber.root!.counter--;
-      }
+    if (handled) {
       return true;
     }
   }
@@ -54,7 +51,7 @@ export function handleError(params: ErrorParams) {
 
   fibersInError.set(fiber.root!, error);
 
-  const handled = _handleError(node, error, true);
+  const handled = _handleError(node, error);
   if (!handled) {
     console.warn(`[Owl] Unhandled error. Destroying the root component`);
     try {

src/component/fibers.ts

@@ -6,8 +6,7 @@ import { STATUS } from "./status";
 export function makeChildFiber(node: ComponentNode, parent: Fiber): Fiber {
   let current = node.fiber;
   if (current) {
-    let root = parent.root;
-    cancelFibers(root, current.children);
+    cancelFibers(current.children);
     current.root = null;
   }
   return new Fiber(node, parent);
@@ -17,9 +16,14 @@ export function makeRootFiber(node: ComponentNode): Fiber {
   let current = node.fiber;
   if (current) {
     let root = current.root!;
-    root.counter -= cancelFibers(root, current.children);
+    // lock root fiber because canceling children fibers may destroy components,
+    // which means any arbitrary code can be run in onWillDestroy, which may
+    // trigger new renderings
+    root.locked = true;
+    root.setCounter(root.counter + 1 - cancelFibers(current.children));
+    root.locked = false;
     current.children = [];
-    root.counter++;
+    current.childrenMap = {};
     current.bdom = null;
     if (fibersInError.has(current)) {
       fibersInError.delete(current);
@@ -35,22 +39,37 @@ export function makeRootFiber(node: ComponentNode): Fiber {
   if (node.patched.length) {
     fiber.patched.push(fiber);
   }
-
   return fiber;
 }
 
+function throwOnRender() {
+  throw new Error("Attempted to render cancelled fiber");
+}
+
 /**
  * @returns number of not-yet rendered fibers cancelled
  */
-function cancelFibers(root: any, fibers: Fiber[]): number {
+function cancelFibers(fibers: Fiber[]): number {
   let result = 0;
   for (let fiber of fibers) {
-    fiber.node.fiber = null;
-    fiber.root = root;
-    if (!fiber.bdom) {
+    let node = fiber.node;
+    fiber.render = throwOnRender;
+    if (node.status === STATUS.NEW) {
+      node.destroy();
+    }
+    node.fiber = null;
+    if (fiber.bdom) {
+      // if fiber has been rendered, this means that the component props have
+      // been updated. however, this fiber will not be patched to the dom, so
+      // it could happen that the next render compare the current props with
+      // the same props, and skip the render completely. With the next line,
+      // we kindly request the component code to force a render, so it works as
+      // expected.
+      node.forceNextRender = true;
+    } else {
       result++;
     }
-    result += cancelFibers(root, fiber.children);
+    result += cancelFibers(fiber.children);
   }
   return result;
 }
@@ -62,19 +81,59 @@ export class Fiber {
   parent: Fiber | null;
   children: Fiber[] = [];
   appliedToDom = false;
+  deep: boolean = false;
+  childrenMap: ComponentNode["children"] = {};
 
   constructor(node: ComponentNode, parent: Fiber | null) {
     this.node = node;
     this.parent = parent;
     if (parent) {
+      this.deep = parent.deep;
       const root = parent.root!;
-      root.counter++;
+      root.setCounter(root.counter + 1);
       this.root = root;
       parent.children.push(this);
     } else {
       this.root = this as any;
     }
   }
+
+  render() {
+    // if some parent has a fiber => register in followup
+    let prev = this.root!.node;
+    let scheduler = prev.app.scheduler;
+    let current = prev.parent;
+    while (current) {
+      if (current.fiber) {
+        let root = current.fiber.root!;
+        if (root.counter === 0 && prev.parentKey! in current.fiber.childrenMap) {
+          current = root.node;
+        } else {
+          scheduler.delayedRenders.push(this);
+          return;
+        }
+      }
+      prev = current;
+      current = current.parent;
+    }
+
+    // there are no current rendering from above => we can render
+    this._render();
+  }
+
+  _render() {
+    const node = this.node;
+    const root = this.root;
+    if (root) {
+      try {
+        (this.bdom as any) = true;
+        this.bdom = node.renderFn();
+      } catch (e) {
+        handleError({ node, error: e });
+      }
+      root.setCounter(root.counter - 1);
+    }
+  }
 }
 
 export class RootFiber extends Fiber {
@@ -109,7 +168,7 @@ export class RootFiber extends Fiber {
       current = undefined;
 
       // Step 2: patching the dom
-      node.patch();
+      node._patch();
       this.locked = false;
 
       // Step 4: calling all mounted lifecycle hooks
@@ -138,6 +197,13 @@ export class RootFiber extends Fiber {
       handleError({ fiber: current || this, error: e });
     }
   }
+
+  setCounter(newValue: number) {
+    this.counter = newValue;
+    if (newValue === 0) {
+      this.node.app.scheduler.flush();
+    }
+  }
 }
 
 type Position = "first-child" | "last-child";
@@ -159,6 +225,8 @@ export class MountFiber extends RootFiber {
     let current: Fiber | undefined = this;
     try {
       const node = this.node;
+      node.children = this.childrenMap;
+      (node.app.constructor as any).validateTarget(this.target);
       if (node.bdom) {
         // this is a complicated situation: if we mount a fiber with an existing
         // bdom, this means that this same fiber was already completed, mounted,

src/component/lifecycle_hooks.ts

@@ -1,67 +1,118 @@
 import { getCurrent } from "./component_node";
 import { nodeErrorHandlers } from "./error_handling";
 
+const TIMEOUT = Symbol("timeout");
+function wrapError(fn: (...args: any[]) => any, hookName: string) {
+  const error = new Error(`The following error occurred in ${hookName}: `) as Error & {
+    cause: any;
+  };
+  const timeoutError = new Error(`${hookName}'s promise hasn't resolved after 3 seconds`);
+  const node = getCurrent();
+  return (...args: any[]) => {
+    try {
+      const result = fn(...args);
+      if (result instanceof Promise) {
+        if (hookName === "onWillStart" || hookName === "onWillUpdateProps") {
+          const fiber = node.fiber;
+          Promise.race([
+            result,
+            new Promise((resolve) => setTimeout(() => resolve(TIMEOUT), 3000)),
+          ]).then((res) => {
+            if (res === TIMEOUT && node.fiber === fiber) {
+              console.warn(timeoutError);
+            }
+          });
+        }
+        return result.catch((cause) => {
+          error.cause = cause;
+          if (cause instanceof Error) {
+            error.message += `"${cause.message}"`;
+          }
+          throw error;
+        });
+      }
+      return result;
+    } catch (cause) {
+      if (cause instanceof Error) {
+        error.message += `"${cause.message}"`;
+      }
+      throw error;
+    }
+  };
+}
+
 // -----------------------------------------------------------------------------
 //  hooks
 // -----------------------------------------------------------------------------
 
 export function onWillStart(fn: () => Promise<void> | void | any) {
-  const node = getCurrent()!;
-  node.willStart.push(fn.bind(node.component));
+  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()!;
-  node.willUpdateProps.push(fn.bind(node.component));
+  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()!;
-  node.mounted.push(fn.bind(node.component));
+  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()!;
-  node.willPatch.unshift(fn.bind(node.component));
+  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()!;
-  node.patched.push(fn.bind(node.component));
+  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()!;
-  node.willUnmount.unshift(fn.bind(node.component));
+  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()!;
-  node.willDestroy.push(fn.bind(node.component));
+  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 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.call(node.component);
+    fn();
     return renderFn();
   };
 }
 
 export function onRendered(fn: () => void | any) {
-  const node = getCurrent()!;
+  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.call(node.component);
+    fn();
     return result;
   };
 }
 
 type OnErrorCallback = (error: any) => void | any;
 export function onError(callback: OnErrorCallback) {
-  const node = getCurrent()!;
+  const node = getCurrent();
   let handlers = nodeErrorHandlers.get(node);
   if (!handlers) {
     handlers = [];

src/component/props_validation.ts

@@ -1,16 +1,16 @@
-import { Component } from "./component";
+import { ComponentConstructor } 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;
+export function applyDefaultProps<P>(props: P, ComponentClass: ComponentConstructor<P>) {
+  const defaultProps = ComponentClass.defaultProps;
   if (defaultProps) {
     for (let propName in defaultProps) {
-      if (props![propName] === undefined) {
-        props![propName] = defaultProps[propName];
+      if ((props as any)[propName] === undefined) {
+        (props as any)[propName] = defaultProps[propName];
       }
     }
   }
@@ -34,13 +34,20 @@ function getPropDescription(staticProps: any) {
  * 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;
+export function validateProps<P>(name: string | ComponentConstructor<P>, props: P, parent?: any) {
+  const ComponentClass =
+    typeof name !== "string"
+      ? name
+      : (parent.constructor.components[name] as ComponentConstructor<P> | undefined);
 
+  if (!ComponentClass) {
+    // this is an error, wrong component. We silently return here instead so the
+    // error is triggered by the usual path ('component' function)
+    return;
+  }
   applyDefaultProps(props, ComponentClass);
 
+  const defaultProps = ComponentClass.defaultProps || {};
   let propsDef = getPropDescription(ComponentClass.props);
   const allowAdditionalProps = "*" in propsDef;
 
@@ -48,8 +55,18 @@ export const validateProps = function (name: string | typeof Component, props: a
     if (propName === "*") {
       continue;
     }
-    if (props[propName] === undefined) {
-      if (propsDef[propName] && !propsDef[propName].optional) {
+    const propDef = propsDef[propName];
+    let isMandatory = !!propDef;
+    if (typeof propDef === "object" && "optional" in propDef) {
+      isMandatory = !propDef.optional;
+    }
+    if (isMandatory && propName in defaultProps) {
+      throw new Error(
+        `A default value cannot be defined for a mandatory prop (name: '${propName}', component: ${ComponentClass.name})`
+      );
+    }
+    if ((props as any)[propName] === undefined) {
+      if (isMandatory) {
         throw new Error(`Missing props '${propName}' (component '${ComponentClass.name}')`);
       } else {
         continue;
@@ -57,7 +74,7 @@ export const validateProps = function (name: string | typeof Component, props: a
     }
     let isValid;
     try {
-      isValid = isValidProp(props[propName], propsDef[propName]);
+      isValid = isValidProp((props as any)[propName], propDef);
     } catch (e) {
       (e as Error).message = `Invalid prop '${propName}' in component ${ComponentClass.name} (${
         (e as Error).message
@@ -75,7 +92,7 @@ export const validateProps = function (name: string | typeof Component, props: a
       }
     }
   }
-};
+}
 
 /**
  * Check if an invidual prop value matches its (static) prop definition

src/component/scheduler.ts

@@ -11,27 +11,16 @@ export class Scheduler {
   // 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"];
+  frame: number = 0;
+  delayedRenders: Fiber[] = [];
 
   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();
-    }
   }
 
   /**
@@ -39,39 +28,49 @@ export class Scheduler {
    * 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();
+    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();
         }
-        this.tasks.delete(fiber);
       }
-    });
-    if (this.tasks.size === 0) {
-      this.stop();
+    }
+
+    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);
+          }
+        }
+      });
     }
   }
 
-  scheduleTasks() {
-    this.requestAnimationFrame(() => {
-      this.flush();
-      if (this.isRunning) {
-        this.scheduleTasks();
+  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/hooks.ts

@@ -11,7 +11,7 @@ import { onMounted, onPatched, onWillUnmount } from "./component/lifecycle_hooks
  * html node or component.
  */
 export function useRef<T extends HTMLElement = HTMLElement>(name: string): { el: T | null } {
-  const node = getCurrent()!;
+  const node = getCurrent();
   const refs = node.refs;
   return {
     get el(): T | null {
@@ -29,7 +29,13 @@ export function useRef<T extends HTMLElement = HTMLElement>(name: string): { el:
  * need a reference to the env of the component calling them.
  */
 export function useEnv<E extends Env>(): E {
-  return getCurrent()!.component.env as any;
+  return getCurrent().component.env as any;
+}
+
+function extendEnv(currentEnv: Object, extension: Object): Object {
+  const env = Object.create(currentEnv);
+  const descrs = Object.getOwnPropertyDescriptors(extension);
+  return Object.freeze(Object.defineProperties(env, descrs));
 }
 
 /**
@@ -38,17 +44,19 @@ export function useEnv<E extends Env>(): E {
  * constructor method.
  */
 export function useSubEnv(envExtension: Env) {
-  const node = getCurrent()!;
-  const env = Object.create(node.childEnv);
-  const descrs = Object.getOwnPropertyDescriptors(envExtension);
-  node.childEnv = Object.freeze(Object.defineProperties(env, descrs));
+  const node = getCurrent();
+  node.component.env = extendEnv(node.component.env as any, envExtension);
+  useChildSubEnv(envExtension);
 }
 
+export function useChildSubEnv(envExtension: Env) {
+  const node = getCurrent();
+  node.childEnv = extendEnv(node.childEnv, envExtension);
+}
 // -----------------------------------------------------------------------------
 // useEffect
 // -----------------------------------------------------------------------------
 
-const NO_OP = () => {};
 /**
  * @param {...any} dependencies the dependencies computed by computeDependencies
  * @returns {void|(()=>void)} a cleanup function that reverses the side
@@ -69,11 +77,11 @@ type Effect = (...dependencies: any[]) => void | (() => void);
  *      NaN !== NaN, which will cause the effect to rerun on every patch.
  */
 export function useEffect(effect: Effect, computeDependencies: () => any[] = () => [NaN]) {
-  let cleanup: () => void;
+  let cleanup: (() => void) | void;
   let dependencies: any[];
   onMounted(() => {
     dependencies = computeDependencies();
-    cleanup = effect(...dependencies) || NO_OP;
+    cleanup = effect(...dependencies);
   });
 
   onPatched(() => {
@@ -81,12 +89,14 @@ export function useEffect(effect: Effect, computeDependencies: () => any[] = ()
     const shouldReapply = newDeps.some((val, i) => val !== dependencies[i]);
     if (shouldReapply) {
       dependencies = newDeps;
-      cleanup();
-      cleanup = effect(...dependencies) || NO_OP;
+      if (cleanup) {
+        cleanup();
+      }
+      cleanup = effect(...dependencies);
     }
   });
 
-  onWillUnmount(() => cleanup());
+  onWillUnmount(() => cleanup && cleanup());
 }
 
 // -----------------------------------------------------------------------------
@@ -112,7 +122,7 @@ export function useExternalListener(
   handler: EventListener,
   eventParams?: AddEventListenerOptions
 ) {
-  const node = getCurrent()!;
+  const node = getCurrent();
   const boundHandler = handler.bind(node.component);
   onMounted(() => target.addEventListener(eventName, boundHandler, eventParams));
   onWillUnmount(() => target.removeEventListener(eventName, boundHandler, eventParams));

src/index.ts

@@ -1,4 +1,3 @@
-import { UTILS } from "./app/template_helpers";
 import {
   config,
   createBlock,
@@ -13,12 +12,10 @@ import {
   comment,
 } from "./blockdom";
 import { mainEventHandler } from "./component/handler";
-import { Portal } from "./portal";
 export type { Reactive } from "./reactivity";
 
 config.shouldNormalizeDom = false;
 config.mainEventHandler = mainEventHandler;
-(UTILS as any).Portal = Portal;
 
 export const blockDom = {
   config,
@@ -38,13 +35,11 @@ export const blockDom = {
 
 export { App, mount } from "./app/app";
 export { Component } from "./component/component";
-export { useComponent } from "./component/component_node";
+export { useComponent, useState } from "./component/component_node";
 export { status } from "./component/status";
-export { Memo } from "./memo";
-export { xml } from "./app/template_set";
-export { useState, reactive } from "./reactivity";
-export { useEffect, useEnv, useExternalListener, useRef, useSubEnv } from "./hooks";
-export { EventBus, whenReady, loadFile, markup } from "./utils";
+export { reactive, markRaw, toRaw } from "./reactivity";
+export { useEffect, useEnv, useExternalListener, useRef, useChildSubEnv, useSubEnv } from "./hooks";
+export { EventBus, whenReady, loadFile, markup, xml } from "./utils";
 export {
   onWillStart,
   onMounted,

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

@@ -1,5 +1,5 @@
 import { onWillUnmount } from "./component/lifecycle_hooks";
-import { xml } from "./app/template_set";
+import { xml } from "./utils";
 import { BDom, text, VNode } from "./blockdom";
 import { Component } from "./component/component";
 

src/reactivity.ts

@@ -1,18 +1,42 @@
-import { onWillUnmount } from "./component/lifecycle_hooks";
-import { ComponentNode, getCurrent } from "./component/component_node";
-import { batched, Callback } from "./utils";
+import { Callback } from "./utils";
 
 // Allows to get the target of a Reactive (used for making a new Reactive from the underlying object)
-const TARGET = Symbol("Target");
+export const TARGET = Symbol("Target");
+// Escape hatch to prevent reactivity system to turn something into a reactive
+const SKIP = Symbol("Skip");
 // Special key to subscribe to, to be notified of key creation/deletion
 const KEYCHANGES = Symbol("Key changes");
 
-type ObjectKey = string | number | symbol;
 type Target = object;
+type Collection = Set<any> | Map<any, any> | WeakMap<any, any>;
+type CollectionRawType = "Set" | "Map" | "WeakMap";
+
 export type Reactive<T extends Target = Target> = T & {
   [TARGET]: any;
 };
 
+export type NonReactive<T extends Target = Target> = T & {
+  [SKIP]: any;
+};
+
+const objectToString = Object.prototype.toString;
+const objectHasOwnProperty = Object.prototype.hasOwnProperty;
+
+const SUPPORTED_RAW_TYPES = new Set(["Object", "Array", "Set", "Map", "WeakMap"]);
+const COLLECTION_RAWTYPES = new Set(["Set", "Map", "WeakMap"]);
+
+/**
+ * extract "RawType" from strings like "[object RawType]" => this lets us ignore
+ * many native objects such as Promise (whose toString is [object Promise])
+ * or Date ([object Date]), while also supporting collections without using
+ * instanceof in a loop
+ *
+ * @param obj the object to check
+ * @returns the raw type of the object
+ */
+function rawType(obj: any) {
+  return objectToString.call(obj).slice(8, -1);
+}
 /**
  * Checks whether a given value can be made into a reactive object.
  *
@@ -20,17 +44,44 @@ export type Reactive<T extends Target = Target> = T & {
  * @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)
-  );
+  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 targetToKeysToCallbacks = new WeakMap<Target, Map<ObjectKey, Set<Callback>>>();
+/**
+ * Mark an object or array so that it is ignored by the reactivity system
+ *
+ * @param value the value to mark
+ * @returns the object itself
+ */
+export function markRaw<T extends Target>(value: T): NonReactive<T> {
+  (value as any)[SKIP] = true;
+  return value as NonReactive<T>;
+}
+
+/**
+ * Given a reactive objet, return the raw (non reactive) underlying object
+ *
+ * @param value a reactive value
+ * @returns the underlying value
+ */
+export function toRaw<T extends object>(value: Reactive<T>): T {
+  return value[TARGET] || value;
+}
+
+const targetToKeysToCallbacks = new WeakMap<Target, Map<PropertyKey, Set<Callback>>>();
 /**
  * Observes a given key on a target with an callback. The callback will be
  * called when the given key changes on the target.
@@ -40,7 +91,7 @@ const targetToKeysToCallbacks = new WeakMap<Target, Map<ObjectKey, Set<Callback>
  *  or deletion)
  * @param callback the function to call when the key changes
  */
-function observeTargetKey(target: Target, key: ObjectKey, callback: Callback): void {
+function observeTargetKey(target: Target, key: PropertyKey, callback: Callback): void {
   if (!targetToKeysToCallbacks.get(target)) {
     targetToKeysToCallbacks.set(target, new Map());
   }
@@ -63,7 +114,7 @@ function observeTargetKey(target: Target, key: ObjectKey, callback: Callback): v
  * @param key the key that changed (or Symbol `KEYCHANGES` if a key was created
  *   or deleted)
  */
-function notifyReactives(target: Target, key: ObjectKey): void {
+function notifyReactives(target: Target, key: PropertyKey): void {
   const keyToCallbacks = targetToKeysToCallbacks.get(target);
   if (!keyToCallbacks) {
     return;
@@ -85,7 +136,7 @@ const callbacksToTargets = new WeakMap<Callback, Set<Target>>();
  *
  * @param callback the callback for which the reactives need to be cleared
  */
-function clearReactivesForCallback(callback: Callback): void {
+export function clearReactivesForCallback(callback: Callback): void {
   const targetsToClear = callbacksToTargets.get(callback);
   if (!targetsToClear) {
     return;
@@ -102,6 +153,17 @@ function clearReactivesForCallback(callback: Callback): void {
   targetsToClear.clear();
 }
 
+export function getSubscriptions(callback: Callback) {
+  const targets = callbacksToTargets.get(callback) || [];
+  return [...targets].map((target) => {
+    const keysToCallbacks = targetToKeysToCallbacks.get(target);
+    return {
+      target,
+      keys: keysToCallbacks ? [...keysToCallbacks.keys()] : [],
+    };
+  });
+}
+
 const reactiveCache = new WeakMap<Target, WeakMap<Callback, Reactive>>();
 /**
  * Creates a reactive proxy for an object. Reading data on the reactive object
@@ -130,10 +192,16 @@ const reactiveCache = new WeakMap<Target, WeakMap<Callback, Reactive>>();
  *  reactive has changed
  * @returns a proxy that tracks changes to it
  */
-export function reactive<T extends Target>(target: T, callback: Callback = () => {}): Reactive<T> {
+export function reactive<T extends Target>(
+  target: T,
+  callback: Callback = () => {}
+): Reactive<T> | NonReactive<T> {
   if (!canBeMadeReactive(target)) {
     throw new Error(`Cannot make the given value reactive`);
   }
+  if (SKIP in target) {
+    return target as NonReactive<T>;
+  }
   const originalTarget = (target as Reactive)[TARGET];
   if (originalTarget) {
     return reactive(originalTarget, callback);
@@ -143,75 +211,247 @@ export function reactive<T extends Target>(target: T, callback: Callback = () =>
   }
   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);
-      },
-    });
+    const targetRawType = rawType(target);
+    const handler = COLLECTION_RAWTYPES.has(targetRawType)
+      ? collectionsProxyHandler(target as Collection, callback, targetRawType as CollectionRawType)
+      : basicProxyHandler<T>(callback);
+    const proxy = new Proxy(target, handler as ProxyHandler<T>) as Reactive<T>;
     reactivesForTarget.set(callback, proxy);
   }
   return reactivesForTarget.get(callback) as Reactive<T>;
 }
-
-const batchedRenderFunctions = new WeakMap<ComponentNode, Callback>();
 /**
- * Creates a reactive object that will be observed by the current component.
- * Reading data from the returned object (eg during rendering) will cause the
- * component to subscribe to that data and be rerendered when it changes.
+ * Creates a basic proxy handler for regular objects and arrays.
  *
- * @param state the state to observe
- * @returns a reactive object that will cause the component to re-render on
- *  relevant changes
- * @see reactive
+ * @param callback @see reactive
+ * @returns a proxy handler object
  */
-export function useState<T extends object>(state: T): Reactive<T> {
-  const node = getCurrent()!;
-  if (!batchedRenderFunctions.has(node)) {
-    batchedRenderFunctions.set(
-      node,
-      batched(() => node.render())
-    );
-    onWillUnmount(() => clearReactivesForCallback(render));
-  }
-  const render = batchedRenderFunctions.get(node)!;
-  const reactiveState = reactive(state, render);
-  return reactiveState;
+function basicProxyHandler<T extends Target>(callback: Callback): ProxyHandler<T> {
+  return {
+    get(target: any, key: PropertyKey, proxy: Reactive<T>) {
+      if (key === TARGET) {
+        return target;
+      }
+      // non-writable non-configurable properties cannot be made reactive
+      const desc = Object.getOwnPropertyDescriptor(target, key);
+      if (desc && !desc.writable && !desc.configurable) {
+        return Reflect.get(target, key, proxy);
+      }
+      observeTargetKey(target, key, callback);
+      return possiblyReactive(Reflect.get(target, key, proxy), callback);
+    },
+    set(target, key, value, proxy) {
+      const isNewKey = !objectHasOwnProperty.call(target, key);
+      const originalValue = Reflect.get(target, key, proxy);
+      const ret = Reflect.set(target, key, value, proxy);
+      if (isNewKey) {
+        notifyReactives(target, KEYCHANGES);
+      }
+      // While Array length may trigger the set trap, it's not actually set by this
+      // method but is updated behind the scenes, and the trap is not called with the
+      // new value. We disable the "same-value-optimization" for it because of that.
+      if (originalValue !== value || (Array.isArray(target) && key === "length")) {
+        notifyReactives(target, key);
+      }
+      return ret;
+    },
+    deleteProperty(target, key) {
+      const ret = Reflect.deleteProperty(target, key);
+      // TODO: only notify when something was actually deleted
+      notifyReactives(target, KEYCHANGES);
+      notifyReactives(target, key);
+      return ret;
+    },
+    ownKeys(target) {
+      observeTargetKey(target, KEYCHANGES, callback);
+      return Reflect.ownKeys(target);
+    },
+    has(target, key) {
+      // TODO: this observes all key changes instead of only the presence of the argument key
+      // observing the key itself would observe value changes instead of presence changes
+      // so we may need a finer grained system to distinguish observing value vs presence.
+      observeTargetKey(target, KEYCHANGES, callback);
+      return Reflect.has(target, key);
+    },
+  } as ProxyHandler<T>;
+}
+/**
+ * Creates a function that will observe the key that is passed to it when called
+ * and delegates to the underlying method.
+ *
+ * @param methodName name of the method to delegate to
+ * @param target @see reactive
+ * @param callback @see reactive
+ */
+function makeKeyObserver(methodName: "has" | "get", target: any, callback: Callback) {
+  return (key: any) => {
+    key = toRaw(key);
+    observeTargetKey(target, key, callback);
+    return possiblyReactive(target[methodName](key), callback);
+  };
+}
+/**
+ * Creates an iterable that will delegate to the underlying iteration method and
+ * observe keys as necessary.
+ *
+ * @param methodName name of the method to delegate to
+ * @param target @see reactive
+ * @param callback @see reactive
+ */
+function makeIteratorObserver(
+  methodName: "keys" | "values" | "entries" | typeof Symbol.iterator,
+  target: any,
+  callback: Callback
+) {
+  return function* () {
+    observeTargetKey(target, KEYCHANGES, callback);
+    const keys = target.keys();
+    for (const item of target[methodName]()) {
+      const key = keys.next().value;
+      observeTargetKey(target, key, callback);
+      yield possiblyReactive(item, callback);
+    }
+  };
+}
+/**
+ * Creates a forEach function that will delegate to forEach on the underlying
+ * collection while observing key changes, and keys as they're iterated over,
+ * and making the passed keys/values reactive.
+ *
+ * @param target @see reactive
+ * @param callback @see reactive
+ */
+function makeForEachObserver(target: any, callback: Callback) {
+  return function forEach(forEachCb: (val: any, key: any, target: any) => void, thisArg: any) {
+    observeTargetKey(target, KEYCHANGES, callback);
+    target.forEach(function (val: any, key: any, targetObj: any) {
+      observeTargetKey(target, key, callback);
+      forEachCb.call(
+        thisArg,
+        possiblyReactive(val, callback),
+        possiblyReactive(key, callback),
+        possiblyReactive(targetObj, callback)
+      );
+    }, thisArg);
+  };
+}
+/**
+ * Creates a function that will delegate to an underlying method, and check if
+ * that method has modified the presence or value of a key, and notify the
+ * reactives appropriately.
+ *
+ * @param setterName name of the method to delegate to
+ * @param getterName name of the method which should be used to retrieve the
+ *  value before calling the delegate method for comparison purposes
+ * @param target @see reactive
+ */
+function delegateAndNotify(
+  setterName: "set" | "add" | "delete",
+  getterName: "has" | "get",
+  target: any
+) {
+  return (key: any, value: any) => {
+    key = toRaw(key);
+    const hadKey = target.has(key);
+    const originalValue = target[getterName](key);
+    const ret = target[setterName](key, value);
+    const hasKey = target.has(key);
+    if (hadKey !== hasKey) {
+      notifyReactives(target, KEYCHANGES);
+    }
+    if (originalValue !== value) {
+      notifyReactives(target, key);
+    }
+    return ret;
+  };
+}
+/**
+ * Creates a function that will clear the underlying collection and notify that
+ * the keys of the collection have changed.
+ *
+ * @param target @see reactive
+ */
+function makeClearNotifier(target: Map<any, any> | Set<any>) {
+  return () => {
+    const allKeys = [...target.keys()];
+    target.clear();
+    notifyReactives(target, KEYCHANGES);
+    for (const key of allKeys) {
+      notifyReactives(target, key);
+    }
+  };
+}
+/**
+ * Maps raw type of an object to an object containing functions that can be used
+ * to build an appropritate proxy handler for that raw type. Eg: when making a
+ * reactive set, calling the has method should mark the key that is being
+ * retrieved as observed, and calling the add or delete method should notify the
+ * reactives that the key which is being added or deleted has been modified.
+ */
+const rawTypeToFuncHandlers = {
+  Set: (target: any, callback: Callback) => ({
+    has: makeKeyObserver("has", target, callback),
+    add: delegateAndNotify("add", "has", target),
+    delete: delegateAndNotify("delete", "has", target),
+    keys: makeIteratorObserver("keys", target, callback),
+    values: makeIteratorObserver("values", target, callback),
+    entries: makeIteratorObserver("entries", target, callback),
+    [Symbol.iterator]: makeIteratorObserver(Symbol.iterator, target, callback),
+    forEach: makeForEachObserver(target, callback),
+    clear: makeClearNotifier(target),
+    get size() {
+      observeTargetKey(target, KEYCHANGES, callback);
+      return target.size;
+    },
+  }),
+  Map: (target: any, callback: Callback) => ({
+    has: makeKeyObserver("has", target, callback),
+    get: makeKeyObserver("get", target, callback),
+    set: delegateAndNotify("set", "get", target),
+    delete: delegateAndNotify("delete", "has", target),
+    keys: makeIteratorObserver("keys", target, callback),
+    values: makeIteratorObserver("values", target, callback),
+    entries: makeIteratorObserver("entries", target, callback),
+    [Symbol.iterator]: makeIteratorObserver(Symbol.iterator, target, callback),
+    forEach: makeForEachObserver(target, callback),
+    clear: makeClearNotifier(target),
+    get size() {
+      observeTargetKey(target, KEYCHANGES, callback);
+      return target.size;
+    },
+  }),
+  WeakMap: (target: any, callback: Callback) => ({
+    has: makeKeyObserver("has", target, callback),
+    get: makeKeyObserver("get", target, callback),
+    set: delegateAndNotify("set", "get", target),
+    delete: delegateAndNotify("delete", "has", target),
+  }),
+};
+/**
+ * Creates a proxy handler for collections (Set/Map/WeakMap)
+ *
+ * @param callback @see reactive
+ * @param target @see reactive
+ * @returns a proxy handler object
+ */
+function collectionsProxyHandler<T extends Collection>(
+  target: T,
+  callback: Callback,
+  targetRawType: CollectionRawType
+): ProxyHandler<T> {
+  // TODO: if performance is an issue we can create the special handlers lazily when each
+  // property is read.
+  const specialHandlers = rawTypeToFuncHandlers[targetRawType](target, callback);
+  return Object.assign(basicProxyHandler(callback), {
+    get(target: any, key: PropertyKey) {
+      if (key === TARGET) {
+        return target;
+      }
+      if (objectHasOwnProperty.call(specialHandlers, key)) {
+        return (specialHandlers as any)[key];
+      }
+      observeTargetKey(target, key, callback);
+      return possiblyReactive(target[key], callback);
+    },
+  }) as ProxyHandler<T>;
 }

src/utils.ts

@@ -15,15 +15,26 @@ export function batched(callback: Callback): Callback {
     await Promise.resolve();
     if (!called) {
       called = true;
-      callback();
       // wait for all calls in this microtick to fall through before resetting "called"
-      // so that only the first call to the batched function calls the original callback
-      await Promise.resolve();
-      called = false;
+      // so that only the first call to the batched function calls the original callback.
+      // Schedule this before calling the callback so that calls to the batched function
+      // within the callback will proceed only after resetting called to false, and have
+      // a chance to execute the callback again
+      Promise.resolve().then(() => (called = false));
+      callback();
     }
   };
 }
 
+export function validateTarget(target: HTMLElement) {
+  if (!(target instanceof HTMLElement)) {
+    throw new Error("Cannot mount component: the target is not a valid DOM element");
+  }
+  if (!document.body.contains(target)) {
+    throw new Error("Cannot mount a component on a detached dom node");
+  }
+}
+
 export class EventBus extends EventTarget {
   trigger(name: string, payload?: any) {
     this.dispatchEvent(new CustomEvent(name, { detail: payload }));
@@ -62,3 +73,17 @@ export class Markup extends String {}
 export function markup(value: any) {
   return new Markup(value);
 }
+
+// -----------------------------------------------------------------------------
+//  xml tag helper
+// -----------------------------------------------------------------------------
+export const globalTemplates: { [key: string]: string | Element } = {};
+
+export function xml(...args: Parameters<typeof String.raw>) {
+  const name = `__template__${xml.nextId++}`;
+  const value = String.raw(...args);
+  globalTemplates[name] = value;
+  return name;
+}
+
+xml.nextId = 1;

tests/__snapshots__/reactivity.test.ts.snap

@@ -131,7 +131,7 @@ exports[`Reactivity: useState parent and children subscribed to same context 1`]
   let block1 = createBlock(\`<div><block-child-0/><block-text-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    const b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
     let txt1 = ctx['contextObj'].b;
     return block1([txt1], [b2]);
   }
@@ -223,8 +223,8 @@ exports[`Reactivity: useState two components are updated in parallel 1`] = `
   let block1 = createBlock(\`<div><block-child-0/><block-child-1/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
-    let b3 = component(\`Child\`, {}, key + \`__2\`, node, ctx);
+    const b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    const b3 = component(\`Child\`, {}, key + \`__2\`, node, ctx);
     return block1([], [b2, b3]);
   }
 }"
@@ -252,8 +252,8 @@ exports[`Reactivity: useState two components can subscribe to same context 1`] =
   let block1 = createBlock(\`<div><block-child-0/><block-child-1/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
-    let b3 = component(\`Child\`, {}, key + \`__2\`, node, ctx);
+    const b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    const b3 = component(\`Child\`, {}, key + \`__2\`, node, ctx);
     return block1([], [b2, b3]);
   }
 }"
@@ -281,8 +281,8 @@ exports[`Reactivity: useState two independent components on different levels are
   let block1 = createBlock(\`<div><block-child-0/><block-child-1/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
-    let b3 = component(\`Parent\`, {}, key + \`__2\`, node, ctx);
+    const b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    const b3 = component(\`Parent\`, {}, key + \`__2\`, node, ctx);
     return block1([], [b2, b3]);
   }
 }"
@@ -310,7 +310,7 @@ exports[`Reactivity: useState two independent components on different levels are
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    const b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -340,14 +340,14 @@ exports[`Reactivity: useState useless atoms should be deleted 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(Object.keys(ctx['state']));
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(Object.keys(ctx['state']));;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`id\`] = v_block2[i1];
-      let key1 = ctx['id'];
+      const key1 = ctx['id'];
       c_block2[i1] = withKey(component(\`Quantity\`, {id: ctx['id']}, key + \`__1__\${key1}\`, node, ctx), key1);
     }
     ctx = ctx.__proto__;
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     let txt1 = ctx['total'];
     let txt2 = Object.keys(ctx['state']).length;
     return block1([txt1, txt2], [b2]);

tests/blockdom/block_attributes.test.ts

@@ -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_refs.test.ts

@@ -1,4 +1,5 @@
 import { createBlock, mount, patch, remove } from "../../src/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/event_catcher.test.ts

@@ -0,0 +1,54 @@
+import { config, createBlock, createCatcher, mount } from "../../src/blockdom";
+import { makeTestFixture } from "./helpers";
+import { mainEventHandler } from "../../src/component/handler";
+
+//------------------------------------------------------------------------------
+// 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/compiler/__snapshots__/event_handling.test.ts.snap

@@ -70,17 +70,17 @@ 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]);
   }
 }"
@@ -140,10 +140,10 @@ exports[`t-on handler is bound to proper owner, part 2 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block1, v_block1, l_block1, c_block1] = prepareList([1]);
+    const [k_block1, v_block1, l_block1, c_block1] = prepareList([1]);;
     for (let i1 = 0; i1 < l_block1; i1++) {
       ctx[\`value\`] = v_block1[i1];
-      let key1 = ctx['value'];
+      const key1 = ctx['value'];
       let hdlr1 = [ctx['add'], ctx];
       c_block1[i1] = withKey(block2([hdlr1]), key1);
     }
@@ -188,14 +188,14 @@ exports[`t-on handler is bound to proper owner, part 4 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block1, v_block1, l_block1, c_block1] = prepareList([1]);
+    const [k_block1, v_block1, l_block1, c_block1] = prepareList([1]);;
     for (let i1 = 0; i1 < l_block1; i1++) {
       ctx[\`value\`] = v_block1[i1];
       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);
@@ -271,7 +271,7 @@ exports[`t-on t-on modifiers (native listener) t-on combined with t-out 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     let hdlr1 = [ctx['onClick'], ctx];
-    let b2 = safeOutput(ctx['html']);
+    const b2 = safeOutput(ctx['html']);
     return block1([hdlr1], [b2]);
   }
 }"
@@ -347,17 +347,17 @@ 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]);
   }
 }"
@@ -478,7 +478,7 @@ exports[`t-on t-on with t-call 1`] = `
   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]);
   }
 }"
@@ -508,7 +508,7 @@ exports[`t-on t-on, with arguments and t-call 1`] = `
   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]);
   }
 }"

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

@@ -30,28 +30,28 @@ exports[`misc complex template 1`] = `
       b3 = block3();
     }
     ctx = Object.create(ctx);
-    const [k_block4, v_block4, l_block4, c_block4] = prepareList(ctx['batch'].slot_ids.filter(slot=>slot.build_id.id&&!slot.trigger_id.manual&&(ctx['options'].trigger_display[slot.trigger_id.id])));
+    const [k_block4, v_block4, l_block4, c_block4] = prepareList(ctx['batch'].slot_ids.filter(_slot=>_slot.build_id.id&&!_slot.trigger_id.manual&&(ctx['options'].trigger_display[_slot.trigger_id.id])));;
     for (let i1 = 0; i1 < l_block4; i1++) {
       ctx[\`slot\`] = v_block4[i1];
-      let key1 = ctx['slot'].id;
-      c_block4[i1] = withKey(component(\`SlotButton\`, {class: ctx['slot_container'],slot: ctx['slot']}, key + \`__1__\${key1}\`, node, ctx), key1);
+      const key1 = ctx['slot'].id;
+      c_block4[i1] = withKey(component(\`SlotButton\`, {class: ctx['slot_container'], slot: ctx['slot']}, key + \`__1__\${key1}\`, node, ctx), key1);
     }
     ctx = ctx.__proto__;
     b4 = list(c_block4);
     ctx = Object.create(ctx);
-    const [k_block6, v_block6, l_block6, c_block6] = prepareList([1,2,3,4]);
+    const [k_block6, v_block6, l_block6, c_block6] = prepareList([1,2,3,4]);;
     for (let i1 = 0; i1 < l_block6; i1++) {
       ctx[\`x\`] = v_block6[i1];
-      let key1 = ctx['x'];
+      const key1 = ctx['x'];
       c_block6[i1] = withKey(block7(), key1);
     }
     ctx = ctx.__proto__;
     b6 = list(c_block6);
     ctx = Object.create(ctx);
-    const [k_block8, v_block8, l_block8, c_block8] = prepareList(ctx['commit_links']);
+    const [k_block8, v_block8, l_block8, c_block8] = prepareList(ctx['commit_links']);;
     for (let i1 = 0; i1 < l_block8; i1++) {
       ctx[\`commit_link\`] = v_block8[i1];
-      let key1 = ctx['commit_link'].id;
+      const key1 = ctx['commit_link'].id;
       let b10,b11,b12,b13;
       let attr5 = \`/runbot/commit/\${ctx['commit_link'].commit_id}\`;
       let attr6 = \`badge badge-light batch_commit match_type_\${ctx['commit_link'].match_type}\`;
@@ -96,35 +96,35 @@ exports[`misc global 1`] = `
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList([4,5,6]);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList([4,5,6]);;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`value\`] = v_block2[i1];
       ctx[\`value_first\`] = i1 === 0;
       ctx[\`value_last\`] = i1 === v_block2.length - 1;
       ctx[\`value_index\`] = i1;
       ctx[\`value_value\`] = k_block2[i1];
-      let key1 = ctx['value'];
+      const key1 = ctx['value'];
       let txt1 = ctx['value'];
-      let b4 = block4([txt1]);
+      const b4 = block4([txt1]);
       ctx = Object.create(ctx);
       ctx[isBoundary] = 1;
       ctx = Object.create(ctx);
       ctx[isBoundary] = 1;
       setContextValue(ctx, \\"foo\\", 'aaa');
-      let b6 = callTemplate_1.call(this, ctx, node, key + \`__1__\${key1}\`);
+      const b6 = callTemplate_1.call(this, ctx, node, key + \`__1__\${key1}\`);
       ctx = ctx.__proto__;
-      let b7 = callTemplate_2.call(this, ctx, node, key + \`__2__\${key1}\`);
+      const b7 = callTemplate_2.call(this, ctx, node, key + \`__2__\${key1}\`);
       setContextValue(ctx, \\"foo\\", 'bbb');
-      let b8 = callTemplate_3.call(this, ctx, node, key + \`__3__\${key1}\`);
-      let b5 = multi([b6, b7, b8]);
+      const b8 = callTemplate_3.call(this, ctx, node, key + \`__3__\${key1}\`);
+      const b5 = multi([b6, b7, b8]);
       ctx[zero] = b5;
-      let b9 = callTemplate_4.call(this, ctx, node, key + \`__4__\${key1}\`);
+      const b9 = callTemplate_4.call(this, ctx, node, key + \`__4__\${key1}\`);
       ctx = ctx.__proto__;
       c_block2[i1] = withKey(multi([b4, b9]), key1);
     }
     ctx = ctx.__proto__;
-    let b2 = list(c_block2);
-    let b10 = callTemplate_5.call(this, ctx, node, key + \`__5\`);
+    const b2 = list(c_block2);
+    const b10 = callTemplate_5.call(this, ctx, node, key + \`__5\`);
     return block1([], [b2, b10]);
   }
 }"
@@ -155,7 +155,7 @@ exports[`misc global 3`] = `
   
   return function template(ctx, node, key = \\"\\") {
     let attr1 = 'agüero';
-    let b2 = ctx[zero];
+    const b2 = ctx[zero];
     return block1([attr1], [b2]);
   }
 }"
@@ -170,8 +170,8 @@ exports[`misc global 4`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b3 = text(\`toto default\`);
-    let b2 = withDefault(safeOutput(ctx['toto']), b3);
+    const b3 = text(\`toto default\`);
+    const b2 = withDefault(safeOutput(ctx['toto']), b3);
     return block1([], [b2]);
   }
 }"
@@ -221,10 +221,10 @@ exports[`misc other complex template 1`] = `
     let attr1 = \`/runbot/\${ctx['project'].slug}\`;
     let txt1 = ctx['project'].name;
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['projects']);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['projects']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`project\`] = v_block2[i1];
-      let key1 = ctx['project'].id;
+      const key1 = ctx['project'].id;
       let hdlr1 = [ctx['selectProject'](ctx['project']), ctx];
       let txt2 = ctx['project'].name;
       c_block2[i1] = withKey(block3([hdlr1, txt2]), key1);
@@ -241,12 +241,12 @@ exports[`misc other complex template 1`] = `
         if (ctx['nb_assigned_errors']&&ctx['nb_assigned_errors']>0) {
           let attr3 = \`You have \${ctx['nb_assigned_errors']} random bug assigned\`;
           let txt3 = ctx['nb_assigned_errors'];
-          let b8 = block8([attr3, txt3]);
-          let b9 = block9();
+          const b8 = block8([attr3, txt3]);
+          const b9 = block9();
           b7 = multi([b8, b9]);
         } else if (ctx['nb_build_errors']&&ctx['nb_build_errors']>0) {
-          let b11 = block11();
-          let b12 = block12();
+          const b11 = block11();
+          const b12 = block12();
           b10 = multi([b11, b12]);
         }
         let txt4 = ctx['user'].name.length>25?ctx['user'].namesubstring(0,23)+'...':ctx['user'].name;
@@ -261,17 +261,17 @@ exports[`misc other complex template 1`] = `
     let hdlr3 = [ctx['toggleMore'], ctx];
     if (ctx['categories']&&ctx['categories'].length>1) {
       ctx = Object.create(ctx);
-      const [k_block15, v_block15, l_block15, c_block15] = prepareList(ctx['categories']);
+      const [k_block15, v_block15, l_block15, c_block15] = prepareList(ctx['categories']);;
       for (let i1 = 0; i1 < l_block15; i1++) {
         ctx[\`category\`] = v_block15[i1];
-        let key1 = ctx['category'].id;
+        const key1 = ctx['category'].id;
         let attr6 = ctx['category'].id;
         let attr7 = ctx['category'].id==ctx['options'].active_category_id;
         let txt5 = ctx['category'].name;
         c_block15[i1] = withKey(block16([attr6, attr7, txt5]), key1);
       }
       ctx = ctx.__proto__;
-      let b15 = list(c_block15);
+      const b15 = list(c_block15);
       b14 = block14([], [b15]);
     }
     let attr8 = ctx['search'].value;
@@ -280,10 +280,10 @@ exports[`misc other complex template 1`] = `
     let hdlr6 = [ctx['clearSearch'], ctx];
     if (ctx['triggers']) {
       ctx = Object.create(ctx);
-      const [k_block18, v_block18, l_block18, c_block18] = prepareList(ctx['triggers']);
+      const [k_block18, v_block18, l_block18, c_block18] = prepareList(ctx['triggers']);;
       for (let i1 = 0; i1 < l_block18; i1++) {
         ctx[\`trigger\`] = v_block18[i1];
-        let key1 = ctx['trigger'].id;
+        const key1 = ctx['trigger'].id;
         let b20;
         if (!ctx['trigger'].manual&&ctx['trigger'].project_id===ctx['project'].id&&ctx['trigger'].category_id===ctx['options'].active_category_id) {
           let attr9 = \`trigger_\${ctx['trigger'].id}\`;
@@ -298,12 +298,12 @@ exports[`misc other complex template 1`] = `
         c_block18[i1] = withKey(multi([b20]), key1);
       }
       ctx = ctx.__proto__;
-      let b18 = list(c_block18);
+      const b18 = list(c_block18);
       let hdlr8 = [ctx['triggerAll'], ctx];
       let hdlr9 = [ctx['triggerNone'], ctx];
       let hdlr10 = [ctx['triggerDefault'], ctx];
       let hdlr11 = [ctx['toggleSettingsMenu'], ctx];
-      let b21 = block21([hdlr8, hdlr9, hdlr10, hdlr11]);
+      const b21 = block21([hdlr8, hdlr9, hdlr10, hdlr11]);
       b17 = multi([b18, b21]);
     }
     if (ctx['load_infos']) {
@@ -316,8 +316,8 @@ exports[`misc other complex template 1`] = `
     if (!ctx['project']) {
       b24 = block24();
     } else {
-      let b26 = component(\`BundlesList\`, {bundles: ctx['bundles'].sticky,category_custom_views: ctx['category_custom_views'],search: ctx['search']}, key + \`__2\`, node, ctx);
-      let b27 = component(\`BundlesList\`, {bundles: ctx['bundles'].dev,search: ctx['search']}, key + \`__3\`, node, ctx);
+      const b26 = component(\`BundlesList\`, {bundles: ctx['bundles'].sticky, category_custom_views: ctx['category_custom_views'], search: ctx['search']}, key + \`__2\`, node, ctx);
+      const b27 = component(\`BundlesList\`, {bundles: ctx['bundles'].dev, search: ctx['search']}, key + \`__3\`, node, ctx);
       b25 = block25([], [b26, b27]);
     }
     return block1([attr1, txt1, hdlr2, hdlr3, attr8, hdlr4, hdlr5, ref1, hdlr6, ref2], [b2, b4, b14, b17, b22, b23, b24, b25]);

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

@@ -10,14 +10,14 @@ exports[`memory t-foreach does not leak stuff in global scope 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList([3,2,1]);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList([3,2,1]);;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`item\`] = v_block2[i1];
       ctx[\`item_index\`] = i1;
-      let key1 = ctx['item_index'];
+      const key1 = ctx['item_index'];
       c_block2[i1] = withKey(text(ctx['item']), key1);
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     return block1([], [b2]);
   }
 }"

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

@@ -211,8 +211,8 @@ exports[`simple templates, mostly static multiple root nodes 1`] = `
   let block3 = createBlock(\`<span>hey</span>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = block2();
-    let b3 = block3();
+    const b2 = block2();
+    const b3 = block3();
     return multi([b2, b3]);
   }
 }"
@@ -246,8 +246,8 @@ exports[`simple templates, mostly static static text and dynamic text (no t tag)
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = text(\`hello \`);
-    let b3 = text(ctx['text']);
+    const b2 = text(\`hello \`);
+    const b3 = text(ctx['text']);
     return multi([b2, b3]);
   }
 }"
@@ -259,8 +259,8 @@ exports[`simple templates, mostly static static text and dynamic text 1`] = `
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = text(\`hello \`);
-    let b3 = text(ctx['text']);
+    const b2 = text(\`hello \`);
+    const b3 = text(ctx['text']);
     return multi([b2, b3]);
   }
 }"
@@ -347,8 +347,8 @@ exports[`simple templates, mostly static two t-escs next to each other 1`] = `
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = text(ctx['text1']);
-    let b3 = text(ctx['text2']);
+    const b2 = text(ctx['text1']);
+    const b3 = text(ctx['text2']);
     return multi([b2, b3]);
   }
 }"
@@ -360,8 +360,8 @@ exports[`simple templates, mostly static two t-escs next to each other 2`] = `
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = text(ctx['text1']);
-    let b3 = text(ctx['text2']);
+    const b2 = text(ctx['text1']);
+    const b3 = text(ctx['text2']);
     return multi([b2, b3]);
   }
 }"

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

@@ -52,28 +52,63 @@ exports[`properly support svg namespace to svg tags added even if already in svg
 }"
 `;
 
-exports[`properly support svg svg namespace added to sub-blocks (t-call) 1`] = `
+exports[`properly support svg svg creates new block if it is within html -- 2 1`] = `
 "function anonymous(bdom, helpers
 ) {
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
-  let { getTemplate } = helpers;
-  const callTemplate_1 = getTemplate(\`path\`, \\"http://www.w3.org/2000/svg\\");
   
-  let block1 = createBlock(\`<svg block-ns=\\"http://www.w3.org/2000/svg\\"><block-child-0/></svg>\`);
+  let block1 = createBlock(\`<div><block-child-0/></div>\`);
+  let block2 = createBlock(\`<svg block-ns=\\"http://www.w3.org/2000/svg\\"><polygon fill=\\"#000000\\" points=\\"0 0 4 4 8 0\\" transform=\\"translate(5 7)\\"/><block-child-0/></svg>\`);
+  let block3 = createBlock(\`<path block-ns=\\"http://www.w3.org/2000/svg\\"/>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    let b3;
+    if (ctx['hasPath']) {
+      b3 = block3();
+    }
+    const b2 = block2([], [b3]);
     return block1([], [b2]);
   }
 }"
 `;
 
-exports[`properly support svg svg namespace added to sub-blocks (t-call) 2`] = `
+exports[`properly support svg svg creates new block if it is within html 1`] = `
 "function anonymous(bdom, helpers
 ) {
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
   
-  let block1 = createBlock(\`<path/>\`);
+  let block1 = createBlock(\`<div><block-child-0/></div>\`);
+  let block2 = createBlock(\`<svg block-ns=\\"http://www.w3.org/2000/svg\\"><polygon fill=\\"#000000\\" points=\\"0 0 4 4 8 0\\" transform=\\"translate(5 7)\\"/></svg>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = block2();
+    return block1([], [b2]);
+  }
+}"
+`;
+
+exports[`properly support svg svg namespace added to sub templates if root tag is path 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { getTemplate } = helpers;
+  const callTemplate_1 = 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(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block1 = createBlock(\`<path block-ns=\\"http://www.w3.org/2000/svg\\"/>\`);
   
   return function template(ctx, node, key = \\"\\") {
     return block1();

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

@@ -10,7 +10,7 @@ exports[`t-call (template calling) basic caller 1`] = `
   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]);
   }
 }"
@@ -69,12 +69,12 @@ exports[`t-call (template calling) call with several sub nodes on same line 1`]
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1;
-    let b3 = block3();
-    let b4 = text(\` \`);
-    let b5 = block5();
-    let b2 = multi([b3, b4, b5]);
+    const b3 = block3();
+    const b4 = text(\` \`);
+    const b5 = block5();
+    const b2 = multi([b3, b4, b5]);
     ctx[zero] = b2;
-    let b6 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    const b6 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
     return block1([], [b6]);
   }
 }"
@@ -89,7 +89,7 @@ exports[`t-call (template calling) call with several sub nodes on same line 2`]
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = ctx[zero];
+    const b2 = ctx[zero];
     return block1([], [b2]);
   }
 }"
@@ -109,12 +109,12 @@ exports[`t-call (template calling) cascading t-call t-out='0' 1`] = `
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1;
-    let b3 = block3();
-    let b4 = text(\` \`);
-    let b5 = block5();
-    let b2 = multi([b3, b4, b5]);
+    const b3 = block3();
+    const b4 = text(\` \`);
+    const b5 = block5();
+    const b2 = multi([b3, b4, b5]);
     ctx[zero] = b2;
-    let b6 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    const b6 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
     return block1([], [b6]);
   }
 }"
@@ -133,11 +133,11 @@ exports[`t-call (template calling) cascading t-call t-out='0' 2`] = `
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1;
-    let b3 = block3();
-    let b4 = ctx[zero];
-    let b2 = multi([b3, b4]);
+    const b3 = block3();
+    const b4 = ctx[zero];
+    const b2 = multi([b3, b4]);
     ctx[zero] = b2;
-    let b5 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    const b5 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
     return block1([], [b5]);
   }
 }"
@@ -156,11 +156,11 @@ exports[`t-call (template calling) cascading t-call t-out='0' 3`] = `
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1;
-    let b3 = block3();
-    let b4 = ctx[zero];
-    let b2 = multi([b3, b4]);
+    const b3 = block3();
+    const b4 = ctx[zero];
+    const b2 = multi([b3, b4]);
     ctx[zero] = b2;
-    let b5 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    const b5 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
     return block1([], [b5]);
   }
 }"
@@ -175,7 +175,7 @@ exports[`t-call (template calling) cascading t-call t-out='0' 4`] = `
   let block1 = createBlock(\`<div><span>cascade 2</span><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = ctx[zero];
+    const b2 = ctx[zero];
     return block1([], [b2]);
   }
 }"
@@ -194,10 +194,10 @@ exports[`t-call (template calling) cascading t-call t-out='0', without external
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1;
-    let b2 = block2();
-    let b3 = text(\` \`);
-    let b4 = block4();
-    let b1 = multi([b2, b3, b4]);
+    const b2 = block2();
+    const b3 = text(\` \`);
+    const b4 = block4();
+    const b1 = multi([b2, b3, b4]);
     ctx[zero] = b1;
     return callTemplate_1.call(this, ctx, node, key + \`__1\`);
   }
@@ -216,9 +216,9 @@ exports[`t-call (template calling) cascading t-call t-out='0', without external
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1;
-    let b2 = block2();
-    let b3 = ctx[zero];
-    let b1 = multi([b2, b3]);
+    const b2 = block2();
+    const b3 = ctx[zero];
+    const b1 = multi([b2, b3]);
     ctx[zero] = b1;
     return callTemplate_1.call(this, ctx, node, key + \`__1\`);
   }
@@ -237,9 +237,9 @@ exports[`t-call (template calling) cascading t-call t-out='0', without external
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1;
-    let b2 = block2();
-    let b3 = ctx[zero];
-    let b1 = multi([b2, b3]);
+    const b2 = block2();
+    const b3 = ctx[zero];
+    const b1 = multi([b2, b3]);
     ctx[zero] = b1;
     return callTemplate_1.call(this, ctx, node, key + \`__1\`);
   }
@@ -255,8 +255,8 @@ exports[`t-call (template calling) cascading t-call t-out='0', without external
   let block2 = createBlock(\`<span>cascade 2</span>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = block2();
-    let b3 = ctx[zero];
+    const b2 = block2();
+    const b3 = ctx[zero];
     return multi([b2, b3]);
   }
 }"
@@ -272,7 +272,7 @@ exports[`t-call (template calling) dynamic t-call 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     const template1 = (ctx['template']);
-    let b2 = call(this, template1, ctx, node, key + \`__1\`);
+    const b2 = call(this, template1, ctx, node, key + \`__1\`);
     return block1([], [b2]);
   }
 }"
@@ -319,7 +319,7 @@ exports[`t-call (template calling) inherit context 1`] = `
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1
     setContextValue(ctx, \\"foo\\", 1);
-    let b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    const b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
     return block1([], [b2]);
   }
 }"
@@ -370,7 +370,7 @@ exports[`t-call (template calling) recursive template, part 2 1`] = `
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1;
     setContextValue(ctx, \\"node\\", ctx['root']);
-    let b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    const b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
     return block1([], [b2]);
   }
 }"
@@ -390,21 +390,21 @@ exports[`t-call (template calling) recursive template, part 2 2`] = `
     ctx[isBoundary] = 1
     let txt1 = ctx['node'].val;
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['node'].children||[]);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['node'].children||[]);;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`subtree\`] = v_block2[i1];
       ctx[\`subtree_first\`] = i1 === 0;
       ctx[\`subtree_last\`] = i1 === v_block2.length - 1;
       ctx[\`subtree_index\`] = i1;
       ctx[\`subtree_value\`] = k_block2[i1];
-      let key1 = ctx['subtree_index'];
+      const key1 = ctx['subtree_index'];
       ctx = Object.create(ctx);
       ctx[isBoundary] = 1;
       setContextValue(ctx, \\"node\\", ctx['subtree']);
       c_block2[i1] = withKey(callTemplate_1.call(this, ctx, node, key + \`__1__\${key1}\`), key1);
       ctx = ctx.__proto__;
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     return block1([txt1], [b2]);
   }
 }"
@@ -425,7 +425,7 @@ exports[`t-call (template calling) recursive template, part 3 1`] = `
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1;
     setContextValue(ctx, \\"node\\", ctx['root']);
-    let b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    const b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
     return block1([], [b2]);
   }
 }"
@@ -445,21 +445,21 @@ exports[`t-call (template calling) recursive template, part 3 2`] = `
     ctx[isBoundary] = 1
     let txt1 = ctx['node'].val;
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['node'].children||[]);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['node'].children||[]);;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`subtree\`] = v_block2[i1];
       ctx[\`subtree_first\`] = i1 === 0;
       ctx[\`subtree_last\`] = i1 === v_block2.length - 1;
       ctx[\`subtree_index\`] = i1;
       ctx[\`subtree_value\`] = k_block2[i1];
-      let key1 = ctx['subtree_index'];
+      const key1 = ctx['subtree_index'];
       ctx = Object.create(ctx);
       ctx[isBoundary] = 1;
       setContextValue(ctx, \\"node\\", ctx['subtree']);
       c_block2[i1] = withKey(callTemplate_1.call(this, ctx, node, key + \`__1__\${key1}\`), key1);
       ctx = ctx.__proto__;
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     return block1([txt1], [b2]);
   }
 }"
@@ -481,7 +481,7 @@ exports[`t-call (template calling) recursive template, part 4: with t-set recurs
     ctx[isBoundary] = 1;
     setContextValue(ctx, \\"recursive_idx\\", 1);
     setContextValue(ctx, \\"node\\", ctx['root']);
-    let b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    const b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
     return block1([], [b2]);
   }
 }"
@@ -503,21 +503,21 @@ exports[`t-call (template calling) recursive template, part 4: with t-set recurs
     let txt1 = ctx['node'].val;
     let txt2 = ctx['recursive_idx'];
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['node'].children||[]);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['node'].children||[]);;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`subtree\`] = v_block2[i1];
       ctx[\`subtree_first\`] = i1 === 0;
       ctx[\`subtree_last\`] = i1 === v_block2.length - 1;
       ctx[\`subtree_index\`] = i1;
       ctx[\`subtree_value\`] = k_block2[i1];
-      let key1 = ctx['subtree_index'];
+      const key1 = ctx['subtree_index'];
       ctx = Object.create(ctx);
       ctx[isBoundary] = 1;
       setContextValue(ctx, \\"node\\", ctx['subtree']);
       c_block2[i1] = withKey(callTemplate_1.call(this, ctx, node, key + \`__1__\${key1}\`), key1);
       ctx = ctx.__proto__;
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     return block1([txt1, txt2], [b2]);
   }
 }"
@@ -538,7 +538,7 @@ exports[`t-call (template calling) scoped parameters 1`] = `
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1;
     setContextValue(ctx, \\"foo\\", 42);
-    let b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    const b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
     ctx = ctx.__proto__;
     let txt1 = ctx['foo'];
     return block1([txt1], [b2]);
@@ -573,7 +573,7 @@ exports[`t-call (template calling) scoped parameters, part 2 1`] = `
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1;
     setContextValue(ctx, \\"foo\\", 42);
-    let b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    const b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
     ctx = ctx.__proto__;
     let txt1 = ctx['foo'];
     return block1([txt1], [b2]);
@@ -602,7 +602,7 @@ exports[`t-call (template calling) t-call allowed on a non t node 1`] = `
   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]);
   }
 }"
@@ -633,7 +633,7 @@ exports[`t-call (template calling) t-call with body content as root of a templat
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1;
-    let b1 = block1();
+    const b1 = block1();
     ctx[zero] = b1;
     return callTemplate_1.call(this, ctx, node, key + \`__1\`);
   }
@@ -649,7 +649,7 @@ exports[`t-call (template calling) t-call with body content as root of a templat
   let block1 = createBlock(\`<foo><block-child-0/></foo>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = ctx[zero];
+    const b2 = ctx[zero];
     return block1([], [b2]);
   }
 }"
@@ -702,7 +702,7 @@ exports[`t-call (template calling) t-call with t-set inside and body text conten
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1;
     setContextValue(ctx, \\"val\\", \`yip yip\`);
-    let b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    const b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
     return block1([], [b2]);
   }
 }"
@@ -735,14 +735,14 @@ exports[`t-call (template calling) t-call with t-set inside and outside 1`] = `
     ctx = Object.create(ctx);
     ctx[isBoundary] = 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[\`v\`] = v_block2[i1];
       ctx[\`v_first\`] = i1 === 0;
       ctx[\`v_last\`] = i1 === v_block2.length - 1;
       ctx[\`v_index\`] = i1;
       ctx[\`v_value\`] = k_block2[i1];
-      let key1 = ctx['v_index'];
+      const key1 = ctx['v_index'];
       setContextValue(ctx, \\"val\\", ctx['v'].val);
       ctx = Object.create(ctx);
       ctx[isBoundary] = 1;
@@ -750,7 +750,7 @@ exports[`t-call (template calling) t-call with t-set inside and outside 1`] = `
       c_block2[i1] = withKey(callTemplate_1.call(this, ctx, node, key + \`__1__\${key1}\`), key1);
       ctx = ctx.__proto__;
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     return block1([], [b2]);
   }
 }"
@@ -783,7 +783,7 @@ exports[`t-call (template calling) t-call with t-set inside and outside. 2 1`] =
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1
     setContextValue(ctx, \\"w\\", 'fromwrapper');
-    let b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    const b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
     return block1([], [b2]);
   }
 }"
@@ -802,14 +802,14 @@ exports[`t-call (template calling) t-call with t-set inside and outside. 2 2`] =
     ctx = Object.create(ctx);
     ctx[isBoundary] = 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[\`v\`] = v_block2[i1];
       ctx[\`v_first\`] = i1 === 0;
       ctx[\`v_last\`] = i1 === v_block2.length - 1;
       ctx[\`v_index\`] = i1;
       ctx[\`v_value\`] = k_block2[i1];
-      let key1 = ctx['v_index'];
+      const key1 = ctx['v_index'];
       setContextValue(ctx, \\"val\\", ctx['v'].val);
       ctx = Object.create(ctx);
       ctx[isBoundary] = 1;
@@ -817,7 +817,7 @@ exports[`t-call (template calling) t-call with t-set inside and outside. 2 2`] =
       c_block2[i1] = withKey(callTemplate_1.call(this, ctx, node, key + \`__1__\${key1}\`), key1);
       ctx = ctx.__proto__;
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     return block1([], [b2]);
   }
 }"
@@ -832,8 +832,8 @@ exports[`t-call (template calling) t-call with t-set inside and outside. 2 3`] =
   
   return function template(ctx, node, key = \\"\\") {
     let txt1 = ctx['val3'];
-    let b2 = block2([txt1]);
-    let b3 = text(ctx['w']);
+    const b2 = block2([txt1]);
+    const b3 = text(ctx['w']);
     return multi([b2, b3]);
   }
 }"
@@ -908,7 +908,7 @@ exports[`t-call (template calling) t-esc inside t-call, with t-set outside 1`] =
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1
     setContextValue(ctx, \\"v\\", \`Hi\`);
-    let b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    const b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
     return block1([], [b2]);
   }
 }"
@@ -938,7 +938,7 @@ exports[`t-call (template calling) with unused body 1`] = `
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1;
-    let b1 = text(\`WHEEE\`);
+    const b1 = text(\`WHEEE\`);
     ctx[zero] = b1;
     return callTemplate_1.call(this, ctx, node, key + \`__1\`);
   }
@@ -999,7 +999,7 @@ exports[`t-call (template calling) with used body 1`] = `
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1;
-    let b1 = text(\`ok\`);
+    const b1 = text(\`ok\`);
     ctx[zero] = b1;
     return callTemplate_1.call(this, ctx, node, key + \`__1\`);
   }
@@ -1036,7 +1036,7 @@ exports[`t-call (template calling) with used setbody 1`] = `
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1;
     setContextValue(ctx, \\"foo\\", 'ok');
-    let b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    const b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
     return block1([], [b2]);
   }
 }"

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

@@ -44,7 +44,7 @@ exports[`debugging t-debug on sub template 2`] = `
   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]);
   }
 }"

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

@@ -82,15 +82,15 @@ exports[`t-esc falsy values in text nodes 1`] = `
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = text(ctx['v1']);
-    let b3 = text(\`:\`);
-    let b4 = text(ctx['v2']);
-    let b5 = text(\`:\`);
-    let b6 = text(ctx['v3']);
-    let b7 = text(\`:\`);
-    let b8 = text(ctx['v4']);
-    let b9 = text(\`:\`);
-    let b10 = text(ctx['v5']);
+    const b2 = text(ctx['v1']);
+    const b3 = text(\`:\`);
+    const b4 = text(ctx['v2']);
+    const b5 = text(\`:\`);
+    const b6 = text(ctx['v3']);
+    const b7 = text(\`:\`);
+    const b8 = text(ctx['v4']);
+    const b9 = text(\`:\`);
+    const b10 = text(ctx['v5']);
     return multi([b2, b3, b4, b5, b6, b7, b8, b9, b10]);
   }
 }"
@@ -160,9 +160,9 @@ 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]);
   }
 }"

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

@@ -10,13 +10,13 @@ exports[`t-foreach does not pollute the rendering context 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList([1]);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList([1]);;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`item\`] = v_block2[i1];
-      let key1 = ctx['item'];
+      const key1 = ctx['item'];
       c_block2[i1] = withKey(text(ctx['item']), key1);
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     return block1([], [b2]);
   }
 }"
@@ -33,14 +33,14 @@ 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]);
   }
 }"
@@ -56,22 +56,22 @@ exports[`t-foreach iterate on items 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList([3,2,1]);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList([3,2,1]);;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`item\`] = v_block2[i1];
       ctx[\`item_index\`] = i1;
       ctx[\`item_value\`] = k_block2[i1];
-      let key1 = ctx['item'];
-      let b4 = text(\` [\`);
-      let b5 = text(ctx['item_index']);
-      let b6 = text(\`: \`);
-      let b7 = text(ctx['item']);
-      let b8 = text(\` \`);
-      let b9 = text(ctx['item_value']);
-      let b10 = text(\`] \`);
+      const key1 = ctx['item'];
+      const b4 = text(\` [\`);
+      const b5 = text(ctx['item_index']);
+      const b6 = text(\`: \`);
+      const b7 = text(ctx['item']);
+      const b8 = text(\` \`);
+      const b9 = text(ctx['item_value']);
+      const b10 = text(\`] \`);
       c_block2[i1] = withKey(multi([b4, b5, b6, b7, b8, b9, b10]), key1);
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     return block1([], [b2]);
   }
 }"
@@ -87,22 +87,22 @@ exports[`t-foreach iterate, dict param 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['value']);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['value']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`item\`] = v_block2[i1];
       ctx[\`item_index\`] = i1;
       ctx[\`item_value\`] = k_block2[i1];
-      let key1 = ctx['item_index'];
-      let b4 = text(\` [\`);
-      let b5 = text(ctx['item_index']);
-      let b6 = text(\`: \`);
-      let b7 = text(ctx['item']);
-      let b8 = text(\` \`);
-      let b9 = text(ctx['item_value']);
-      let b10 = text(\`] \`);
+      const key1 = ctx['item_index'];
+      const b4 = text(\` [\`);
+      const b5 = text(ctx['item_index']);
+      const b6 = text(\`: \`);
+      const b7 = text(ctx['item']);
+      const b8 = text(\` \`);
+      const b9 = text(ctx['item_value']);
+      const b10 = text(\`] \`);
       c_block2[i1] = withKey(multi([b4, b5, b6, b7, b8, b9, b10]), key1);
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     return block1([], [b2]);
   }
 }"
@@ -118,13 +118,13 @@ exports[`t-foreach iterate, position 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(Array(5));
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(Array(5));;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`elem\`] = v_block2[i1];
       ctx[\`elem_first\`] = i1 === 0;
       ctx[\`elem_last\`] = i1 === v_block2.length - 1;
       ctx[\`elem_index\`] = i1;
-      let key1 = ctx['elem'];
+      const key1 = ctx['elem'];
       let b4,b5,b6,b7,b8,b9;
       b4 = text(\` -\`);
       if (ctx['elem_first']) {
@@ -138,7 +138,7 @@ 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]);
   }
 }"
@@ -154,13 +154,13 @@ exports[`t-foreach simple iteration (in a node) 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList([3,2,1]);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList([3,2,1]);;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`item\`] = v_block2[i1];
-      let key1 = ctx['item'];
+      const key1 = ctx['item'];
       c_block2[i1] = withKey(text(ctx['item']), key1);
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     return block1([], [b2]);
   }
 }"
@@ -174,10 +174,10 @@ exports[`t-foreach simple iteration 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'];
       c_block1[i1] = withKey(text(ctx['item']), key1);
     }
     return list(c_block1);
@@ -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);
@@ -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'];
@@ -270,13 +270,13 @@ exports[`t-foreach t-call with body in t-foreach in t-foreach 2`] = `
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = text(\` [\`);
-    let b3 = text(ctx['a']);
-    let b4 = text(\`] [\`);
-    let b5 = text(ctx['b']);
-    let b6 = text(\`] [\`);
-    let b7 = text(ctx['c']);
-    let b8 = text(\`] \`);
+    const b2 = text(\` [\`);
+    const b3 = text(ctx['a']);
+    const b4 = text(\`] [\`);
+    const b5 = text(ctx['b']);
+    const b6 = text(\`] [\`);
+    const b7 = text(ctx['c']);
+    const b8 = text(\`] \`);
     return multi([b2, b3, b4, b5, b6, b7, b8]);
   }
 }"
@@ -294,33 +294,33 @@ exports[`t-foreach t-call without body in t-foreach in t-foreach 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['numbers']);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['numbers']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`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'];
@@ -339,13 +339,13 @@ exports[`t-foreach t-call without body in t-foreach in t-foreach 2`] = `
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1
     setContextValue(ctx, \\"c\\", 'x'+'_'+ctx['a']+'_'+ctx['b']);
-    let b2 = text(\` [\`);
-    let b3 = text(ctx['a']);
-    let b4 = text(\`] [\`);
-    let b5 = text(ctx['b']);
-    let b6 = text(\`] [\`);
-    let b7 = text(ctx['c']);
-    let b8 = text(\`] \`);
+    const b2 = text(\` [\`);
+    const b3 = text(ctx['a']);
+    const b4 = text(\`] [\`);
+    const b5 = text(ctx['b']);
+    const b6 = text(\`] [\`);
+    const b7 = text(ctx['c']);
+    const b8 = text(\`] \`);
     return multi([b2, b3, b4, b5, b6, b7, b8]);
   }
 }"
@@ -361,25 +361,25 @@ exports[`t-foreach t-foreach in t-foreach 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['numbers']);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['numbers']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`number\`] = v_block2[i1];
-      let key1 = ctx['number'];
+      const key1 = ctx['number'];
       ctx = Object.create(ctx);
-      const [k_block3, v_block3, l_block3, c_block3] = prepareList(ctx['letters']);
+      const [k_block3, v_block3, l_block3, c_block3] = prepareList(ctx['letters']);;
       for (let i2 = 0; i2 < l_block3; i2++) {
         ctx[\`letter\`] = v_block3[i2];
-        let key2 = ctx['letter'];
-        let b5 = text(\` [\`);
-        let b6 = text(ctx['number']);
-        let b7 = text(ctx['letter']);
-        let b8 = text(\`] \`);
+        const key2 = ctx['letter'];
+        const b5 = text(\` [\`);
+        const b6 = text(ctx['number']);
+        const b7 = text(ctx['letter']);
+        const b8 = text(\`] \`);
         c_block3[i2] = withKey(multi([b5, b6, b7, b8]), key2);
       }
       ctx = ctx.__proto__;
       c_block2[i1] = withKey(list(c_block3), key1);
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     return block1([], [b2]);
   }
 }"
@@ -395,10 +395,10 @@ exports[`t-foreach t-foreach with t-if inside (no external node) 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['elems']);
+    const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['elems']);;
     for (let i1 = 0; i1 < l_block1; i1++) {
       ctx[\`elem\`] = v_block1[i1];
-      let key1 = ctx['elem'].id;
+      const key1 = ctx['elem'].id;
       let b3;
       if (ctx['elem'].id<3) {
         let txt1 = ctx['elem'].text;
@@ -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;
@@ -433,7 +433,7 @@ 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]);
   }
 }"
@@ -450,13 +450,13 @@ 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]);
   }
 }"
@@ -473,15 +473,15 @@ 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]);
   }
 }"
@@ -500,12 +500,12 @@ exports[`t-foreach with t-memo 1`] = `
     let cache = ctx.cache || {};
     let nextCache = ctx.cache = {};
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['items']);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['items']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`item\`] = v_block2[i1];
-      let key1 = ctx['item'].id;
-      let memo1 = [ctx['item'].x]
-      let vnode1 = cache[key1];
+      const key1 = ctx['item'].id;
+      const memo1 = [ctx['item'].x];
+      const vnode1 = cache[key1];;
       if (vnode1) {
         if (shallowEqual(vnode1.memo, memo1)) {
           c_block2[i1] = vnode1;
@@ -518,7 +518,7 @@ exports[`t-foreach with t-memo 1`] = `
       c_block2[i1] = withKey(block3([txt1, txt2]), key1);
       nextCache[key1] = Object.assign(c_block2[i1], {memo: memo1});
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     return block1([], [b2]);
   }
 }"

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

@@ -29,8 +29,8 @@ exports[`t-if a t-if with two inner nodes 1`] = `
   return function template(ctx, node, key = \\"\\") {
     let b2;
     if (ctx['condition']) {
-      let b3 = block3();
-      let b4 = block4();
+      const b3 = block3();
+      const b4 = block4();
       b2 = multi([b3, b4]);
     }
     return multi([b2]);
@@ -187,8 +187,8 @@ exports[`t-if div containing a t-if with two inner nodes 1`] = `
   return function template(ctx, node, key = \\"\\") {
     let b2;
     if (ctx['condition']) {
-      let b3 = block3();
-      let b4 = block4();
+      const b3 = block3();
+      const b4 = block4();
       b2 = multi([b3, b4]);
     }
     return block1([], [b2]);
@@ -208,8 +208,8 @@ exports[`t-if dynamic content after t-if with two children nodes 1`] = `
   return function template(ctx, node, key = \\"\\") {
     let b2;
     if (ctx['condition']) {
-      let b3 = block3();
-      let b4 = block4();
+      const b3 = block3();
+      const b4 = block4();
       b2 = multi([b3, b4]);
     }
     let txt1 = ctx['text'];
@@ -318,8 +318,8 @@ exports[`t-if t-if and t-else with two nodes 1`] = `
     if (ctx['condition']) {
       b2 = text(\`1\`);
     } else {
-      let b4 = block4();
-      let b5 = block5();
+      const b4 = block4();
+      const b5 = block5();
       b3 = multi([b4, b5]);
     }
     return multi([b2, b3]);
@@ -526,8 +526,8 @@ exports[`t-if two t-ifs next to each other 1`] = `
       b2 = block2([txt1]);
     }
     if (ctx['condition']) {
-      let b4 = block4();
-      let b5 = block5();
+      const b4 = block4();
+      const b5 = block5();
       b3 = multi([b4, b5]);
     }
     return block1([], [b2, b3]);

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

@@ -56,14 +56,14 @@ 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]);
   }
 }"

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

@@ -9,7 +9,7 @@ exports[`t-out literal 1`] = `
   let block1 = createBlock(\`<span><block-child-0/></span>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput('ok');
+    const b2 = safeOutput('ok');
     return block1([], [b2]);
   }
 }"
@@ -40,9 +40,9 @@ 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]);
   }
 }"
@@ -57,8 +57,8 @@ exports[`t-out multiple calls to t-out 2`] = `
   let block1 = createBlock(\`<div><block-child-0/><div>Greeter</div><block-child-1/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = ctx[zero];
-    let b3 = ctx[zero];
+    const b2 = ctx[zero];
+    const b3 = ctx[zero];
     return block1([], [b2, b3]);
   }
 }"
@@ -73,7 +73,7 @@ exports[`t-out not escaping 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['var']);
+    const b2 = safeOutput(ctx['var']);
     return block1([], [b2]);
   }
 }"
@@ -92,9 +92,9 @@ 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]);
   }
 }"
@@ -109,7 +109,7 @@ exports[`t-out t-out 0 2`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = ctx[zero];
+    const b2 = ctx[zero];
     return block1([], [b2]);
   }
 }"
@@ -124,7 +124,7 @@ exports[`t-out t-out and another sibling node 1`] = `
   let block1 = createBlock(\`<span><span>hello</span><block-child-0/></span>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['var']);
+    const b2 = safeOutput(ctx['var']);
     return block1([], [b2]);
   }
 }"
@@ -147,7 +147,7 @@ exports[`t-out t-out bdom 1`] = `
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1
     ctx[\`var\`] = new LazyValue(value1, ctx, node);
-    let b3 = safeOutput(ctx['var']);
+    const b3 = safeOutput(ctx['var']);
     return block1([], [b3]);
   }
 }"
@@ -162,7 +162,7 @@ exports[`t-out t-out block 1`] = `
   let block1 = createBlock(\`<span><block-child-0/></span>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['bdom']);
+    const b2 = safeOutput(ctx['bdom']);
     return block1([], [b2]);
   }
 }"
@@ -177,7 +177,7 @@ exports[`t-out t-out escaped 1`] = `
   let block1 = createBlock(\`<span><block-child-0/></span>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['var']);
+    const b2 = safeOutput(ctx['var']);
     return block1([], [b2]);
   }
 }"
@@ -192,7 +192,7 @@ exports[`t-out t-out markedup 1`] = `
   let block1 = createBlock(\`<span><block-child-0/></span>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['var']);
+    const b2 = safeOutput(ctx['var']);
     return block1([], [b2]);
   }
 }"
@@ -207,8 +207,8 @@ exports[`t-out t-out on a node with a body, as a default 1`] = `
   let block1 = createBlock(\`<span><block-child-0/></span>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b3 = text(\`nope\`);
-    let b2 = withDefault(safeOutput(ctx['var']), b3);
+    const b3 = text(\`nope\`);
+    const b2 = withDefault(safeOutput(ctx['var']), b3);
     return block1([], [b2]);
   }
 }"
@@ -224,8 +224,8 @@ exports[`t-out t-out on a node with a dom node in body, as a default 1`] = `
   let block3 = createBlock(\`<div>nope</div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b3 = block3();
-    let b2 = withDefault(safeOutput(ctx['var']), b3);
+    const b3 = block3();
+    const b2 = withDefault(safeOutput(ctx['var']), b3);
     return block1([], [b2]);
   }
 }"
@@ -240,7 +240,7 @@ exports[`t-out t-out switch escaped 1`] = `
   let block1 = createBlock(\`<span><block-child-0/></span>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['var']);
+    const b2 = safeOutput(ctx['var']);
     return block1([], [b2]);
   }
 }"
@@ -255,7 +255,7 @@ exports[`t-out t-out switch escaped on markup 1`] = `
   let block1 = createBlock(\`<span><block-child-0/></span>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['var']);
+    const b2 = safeOutput(ctx['var']);
     return block1([], [b2]);
   }
 }"
@@ -270,7 +270,7 @@ exports[`t-out t-out switch markup 1`] = `
   let block1 = createBlock(\`<span><block-child-0/></span>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['var']);
+    const b2 = safeOutput(ctx['var']);
     return block1([], [b2]);
   }
 }"
@@ -297,10 +297,10 @@ exports[`t-out t-out switch markup on bdom 1`] = `
     let b3,b5;
     ctx[\`bdom\`] = new LazyValue(value1, ctx, node);
     if (ctx['hasBdom']) {
-      let b4 = safeOutput(ctx['bdom']);
+      const b4 = safeOutput(ctx['bdom']);
       b3 = block3([], [b4]);
     } else {
-      let b6 = safeOutput(ctx['var']);
+      const b6 = safeOutput(ctx['var']);
       b5 = block5([], [b6]);
     }
     return block1([], [b3, b5]);
@@ -317,7 +317,7 @@ exports[`t-out t-out switch markup on escaped 1`] = `
   let block1 = createBlock(\`<span><block-child-0/></span>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['var']);
+    const b2 = safeOutput(ctx['var']);
     return block1([], [b2]);
   }
 }"
@@ -344,7 +344,7 @@ exports[`t-out t-out with arbitrary object 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['var']);
+    const b2 = safeOutput(ctx['var']);
     return block1([], [b2]);
   }
 }"
@@ -359,7 +359,7 @@ exports[`t-out t-out with arbitrary object 2 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['var']);
+    const b2 = safeOutput(ctx['var']);
     return block1([], [b2]);
   }
 }"
@@ -374,7 +374,7 @@ exports[`t-out t-out with comment 1`] = `
   let block1 = createBlock(\`<span><block-child-0/></span>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['var']);
+    const b2 = safeOutput(ctx['var']);
     return block1([], [b2]);
   }
 }"
@@ -401,7 +401,37 @@ exports[`t-out variable 1`] = `
   let block1 = createBlock(\`<span><block-child-0/></span>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['var']);
+    const b2 = safeOutput(ctx['var']);
+    return block1([], [b2]);
+  }
+}"
+`;
+
+exports[`t-out with a String class 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { safeOutput } = helpers;
+  
+  let block1 = createBlock(\`<span><block-child-0/></span>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = safeOutput(ctx['var']);
+    return block1([], [b2]);
+  }
+}"
+`;
+
+exports[`t-out with an extended String class 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { safeOutput } = helpers;
+  
+  let block1 = createBlock(\`<span><block-child-0/></span>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = safeOutput(ctx['var']);
     return block1([], [b2]);
   }
 }"
@@ -416,7 +446,7 @@ exports[`t-raw is deprecated should warn 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['var']);
+    const b2 = safeOutput(ctx['var']);
     return block1([], [b2]);
   }
 }"
@@ -431,7 +461,7 @@ exports[`t-raw is deprecated t-out is actually called in t-raw's place 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['var']);
+    const b2 = safeOutput(ctx['var']);
     return block1([], [b2]);
   }
 }"

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

@@ -41,7 +41,7 @@ exports[`t-ref ref in a t-call 1`] = `
   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]);
   }
 }"
@@ -94,17 +94,17 @@ exports[`t-ref refs in a loop 1`] = `
   return function template(ctx, node, key = \\"\\") {
     const refs = ctx.__owl__.refs;
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['items']);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['items']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`item\`] = v_block2[i1];
-      let key1 = ctx['item'];
+      const key1 = ctx['item'];
       const tKey_1 = ctx['item'];
       const v1 = ctx['item'];
       let ref1 = (el) => refs[\`\${v1}\`] = el;
       let 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]);
   }
 }"

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

@@ -208,7 +208,7 @@ exports[`t-set t-set body is evaluated immediately 1`] = `
     setContextValue(ctx, \\"v1\\", 'before');
     ctx[\`v2\`] = new LazyValue(value1, ctx, node);
     setContextValue(ctx, \\"v1\\", 'after');
-    let b3 = safeOutput(ctx['v2']);
+    const b3 = safeOutput(ctx['v2']);
     return block1([], [b3]);
   }
 }"
@@ -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]);
   }
@@ -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]);
@@ -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]);
   }
@@ -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]);
   }
@@ -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]);
   }
@@ -439,16 +439,16 @@ 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]);
   }
 }"
@@ -463,8 +463,8 @@ exports[`t-set t-set with content and sub t-esc 1`] = `
   let block1 = createBlock(\`<div><block-text-0/></div>\`);
   
   function value1(ctx, node, key = \\"\\") {
-    let b3 = text(ctx['beep']);
-    let b4 = text(\` boop\`);
+    const b3 = text(ctx['beep']);
+    const b4 = text(\` boop\`);
     return multi([b3, b4]);
   }
   
@@ -500,7 +500,7 @@ exports[`t-set t-set with t-value (falsy) and body 1`] = `
     ctx[\`v2\`] = withDefault(ctx['v3'], new LazyValue(value1, ctx, node));
     setContextValue(ctx, \\"v1\\", 'after');
     setContextValue(ctx, \\"v3\\", true);
-    let b3 = safeOutput(ctx['v2']);
+    const b3 = safeOutput(ctx['v2']);
     return block1([], [b3]);
   }
 }"
@@ -528,7 +528,7 @@ exports[`t-set t-set with t-value (truthy) and body 1`] = `
     ctx[\`v2\`] = withDefault(ctx['v3'], new LazyValue(value1, ctx, node));
     setContextValue(ctx, \\"v1\\", 'after');
     setContextValue(ctx, \\"v3\\", false);
-    let b3 = safeOutput(ctx['v2']);
+    const b3 = safeOutput(ctx['v2']);
     return block1([], [b3]);
   }
 }"

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

@@ -8,7 +8,7 @@ exports[`qweb t-tag can fallback if falsy tag 1`] = `
   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)());
   }
 }"
@@ -22,7 +22,7 @@ exports[`qweb t-tag can update 1`] = `
   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)());
   }
 }"
@@ -36,7 +36,7 @@ exports[`qweb t-tag simple usecases 1`] = `
   let block1 = tag => createBlock(\`<\${tag || 't'}/>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let tag1 = 'div';
+    const tag1 = 'div';
     return toggler(tag1, block1(tag1)());
   }
 }"
@@ -50,7 +50,7 @@ exports[`qweb t-tag simple usecases 2`] = `
   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)());
   }
 }"
@@ -64,7 +64,7 @@ exports[`qweb t-tag with multiple attributes 1`] = `
   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)());
   }
 }"
@@ -78,7 +78,7 @@ exports[`qweb t-tag with multiple child nodes 1`] = `
   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)());
   }
 }"
@@ -93,9 +93,9 @@ exports[`qweb t-tag with multiple t-tag in same template 1`] = `
   let block2 = tag => createBlock(\`<\${tag || 't'}>baz</\${tag || 't'}>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let tag1 = ctx['outer'];
-    let tag2 = ctx['inner'];
-    let b2 = toggler(tag2, block2(tag2)());
+    const tag1 = ctx['outer'];
+    const tag2 = ctx['inner'];
+    const b2 = toggler(tag2, block2(tag2)());
     return toggler(tag1, block1(tag1)([], [b2]));
   }
 }"
@@ -110,10 +110,10 @@ exports[`qweb t-tag with multiple t-tag in same template, part 2 1`] = `
   let block3 = tag => createBlock(\`<\${tag || 't'}>baz</\${tag || 't'}>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let tag1 = ctx['brother'];
-    let b2 = toggler(tag1, block2(tag1)());
-    let tag2 = ctx['brother'];
-    let b3 = toggler(tag2, block3(tag2)());
+    const tag1 = ctx['brother'];
+    const b2 = toggler(tag1, block2(tag1)());
+    const tag2 = ctx['brother'];
+    const b3 = toggler(tag2, block3(tag2)());
     return multi([b2, b3]);
   }
 }"

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

@@ -1,5 +1,19 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`loading templates addTemplates does not modify its xml document in place 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block1 = createBlock(\`<div><block-text-0/></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let txt1 = ctx['value'];
+    return block1([txt1]);
+  }
+}"
+`;
+
 exports[`loading templates can initialize qweb with a string 1`] = `
 "function anonymous(bdom, helpers
 ) {
@@ -36,7 +50,7 @@ exports[`loading templates can load a few templates from a xml string 1`] = `
   let block1 = createBlock(\`<ul><block-child-0/></ul>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    const b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
     return block1([], [b2]);
   }
 }"
@@ -51,8 +65,8 @@ exports[`loading templates can load a few templates from a xml string 2`] = `
   let block3 = createBlock(\`<li>foo</li>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = block2();
-    let b3 = block3();
+    const b2 = block2();
+    const b3 = block3();
     return multi([b2, b3]);
   }
 }"
@@ -68,7 +82,7 @@ exports[`loading templates can load a few templates from an XMLDocument 1`] = `
   let block1 = createBlock(\`<ul><block-child-0/></ul>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    const b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
     return block1([], [b2]);
   }
 }"
@@ -83,8 +97,8 @@ exports[`loading templates can load a few templates from an XMLDocument 2`] = `
   let block3 = createBlock(\`<li>foo</li>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = block2();
-    let b3 = block3();
+    const b2 = block2();
+    const b3 = block3();
     return multi([b2, b3]);
   }
 }"

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

@@ -1,11 +1,11 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
-exports[`translation support can set translatable attributes 1`] = `
+exports[`translation support can set and remove translatable attributes 1`] = `
 "function anonymous(bdom, helpers
 ) {
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
   
-  let block1 = createBlock(\`<div tomato=\\"word\\" potato=\\"mot\\" title=\\"word\\">text</div>\`);
+  let block1 = createBlock(\`<div tomato=\\"word\\" potato=\\"mot\\" title=\\"mot\\" label=\\"word\\">text</div>\`);
   
   return function template(ctx, node, key = \\"\\") {
     return block1();

tests/compiler/blacklist.test.ts

@@ -0,0 +1,13 @@
+import { renderToString } from "../helpers";
+
+describe("blacklisted tags and attributes", () => {
+  test("template with block-text tag", () => {
+    const template = `<div><block-text-0/>hello</div>`;
+    expect(() => renderToString(template)).toThrow("Invalid tag name: 'block-text-0'");
+  });
+
+  test("template with block-handler tag", () => {
+    const template = `<div block-handler-0="click">hello</div>`;
+    expect(() => renderToString(template)).toThrow("Invalid attribute: 'block-handler-0'");
+  });
+});

tests/compiler/error_handling.test.ts

@@ -12,15 +12,6 @@ describe("error handling", () => {
     expect(() => context.renderToString("invalidname")).toThrow("Missing template");
   });
 
-  test("cannot add twice the same template", () => {
-    const context = new TestContext();
-    context.addTemplate("test", `<t></t>`);
-    expect(() => context.addTemplate("test", "<div/>", { allowDuplicate: true })).not.toThrow(
-      "already defined"
-    );
-    expect(() => context.addTemplate("test", "<div/>")).toThrow("already defined");
-  });
-
   test("addTemplates throw if parser error", () => {
     const context = new TestContext();
     expect(() => {

tests/compiler/inline_expressions.test.ts

@@ -65,14 +65,14 @@ describe("tokenizer", () => {
   });
 
   test("strings", () => {
-    expect(() => tokenize("'")).toThrow("Invalid expression");
-    expect(() => tokenize("'\\")).toThrow("Invalid expression");
-    expect(() => tokenize("'\\'")).toThrow("Invalid expression");
+    expect(() => tokenize("'")).toThrow("Tokenizer error: could not tokenize `'`");
+    expect(() => tokenize("'\\")).toThrow("Tokenizer error: could not tokenize `'\\`");
+    expect(() => tokenize("'\\'")).toThrow("Tokenizer error: could not tokenize `'\\'`");
     expect(tokenize("'hello ged'")).toEqual([{ type: "VALUE", value: "'hello ged'" }]);
     expect(tokenize("'hello \\'ged\\''")).toEqual([{ type: "VALUE", value: "'hello \\'ged\\''" }]);
 
-    expect(() => tokenize('"')).toThrow("Invalid expression");
-    expect(() => tokenize('"\\"')).toThrow("Invalid expression");
+    expect(() => tokenize('"')).toThrow('Tokenizer error: could not tokenize `"`');
+    expect(() => tokenize('"\\"')).toThrow('Tokenizer error: could not tokenize `"\\"`');
     expect(tokenize('"hello ged"')).toEqual([{ type: "VALUE", value: '"hello ged"' }]);
     expect(tokenize('"hello ged"}')).toEqual([
       { type: "VALUE", value: '"hello ged"' },
@@ -163,17 +163,21 @@ describe("expression evaluation", () => {
   });
 
   test("arrow functions", () => {
-    expect(compileExpr("list.map(e => e.val)")).toBe("ctx['list'].map(e=>e.val)");
-    expect(compileExpr("list.map(e => a + e)")).toBe("ctx['list'].map(e=>ctx['a']+e)");
-    expect(compileExpr("list.map((e) => e)")).toBe("ctx['list'].map((e)=>e)");
+    expect(compileExpr("list.map(e => e.val)")).toBe("ctx['list'].map(_e=>_e.val)");
+    expect(compileExpr("list.map(e => a + e)")).toBe("ctx['list'].map(_e=>ctx['a']+_e)");
+    expect(compileExpr("list.map((e) => e)")).toBe("ctx['list'].map((_e)=>_e)");
     expect(compileExpr("list.map((elem, index) => elem + index)")).toBe(
-      "ctx['list'].map((elem,index)=>elem+index)"
+      "ctx['list'].map((_elem,_index)=>_elem+_index)"
+    );
+    expect(compileExpr("(ev => ev)(e)")).toBe("(_ev=>_ev)(ctx['e'])");
+    expect(compileExpr("(v1) => myFunc(v1)")).toBe("(_v1)=>ctx['myFunc'](_v1)");
+    expect(compileExpr("list.data.map((data) => data)")).toBe(
+      "ctx['list'].data.map((_data)=>_data)"
     );
-    expect(compileExpr("(ev => ev)(e)")).toBe("(ev=>ev)(ctx['e'])");
   });
   test.skip("arrow functions: not yet supported", () => {
     // e is added to localvars in inline_expression but not removed after the arrow func body
-    expect(compileExpr("(e => e)(e)")).toBe("(e=>e)(ctx['e'])");
+    expect(compileExpr("(e => e)(e)")).toBe("(_e=>_e)(ctx['e'])");
   });
 
   test("assignation", () => {

tests/compiler/svg.test.ts

@@ -1,6 +1,6 @@
 import { renderToString, renderToBdom, snapshotEverything, makeTestFixture } from "../helpers";
 import { mount } from "../../src/blockdom";
-import { mount as mountComponent, Component } from "../../src/index"
+import { mount as mountComponent, Component, xml } from "../../src/index";
 
 // NB: check the snapshots to see where the SVG namespaces are added
 snapshotEverything();
@@ -55,23 +55,63 @@ describe("properly support svg", () => {
     }
   });
 
-  test.only("svg namespace added to sub-blocks (t-call)", async () => {
+  test("svg namespace added to sub templates if root tag is path", async () => {
     const templates = `<t>
       <t t-name="svg"><svg><t t-call="path" /></svg></t>
       <t t-name="path"><path /></t>
     </t>
-    `
+    `;
     const fixture = makeTestFixture();
 
     class Svg extends Component {
       static template = "svg";
     }
 
-    await mountComponent(Svg, fixture, {templates})
+    await mountComponent(Svg, fixture, { templates });
     const elems = fixture.querySelectorAll("svg, path");
     expect(elems.length).toEqual(2);
     for (const el of elems) {
       expect(el.namespaceURI).toBe("http://www.w3.org/2000/svg");
     }
   });
+
+  test("svg creates new block if it is within html", async () => {
+    class Test extends Component {
+      static template = xml`
+        <div>
+          <svg>
+            <polygon fill="#000000" points="0 0 4 4 8 0" transform="translate(5 7)"/>
+          </svg>
+        </div>
+      `;
+    }
+    const fixture = makeTestFixture();
+    await mountComponent(Test, fixture);
+    const elems = fixture.querySelectorAll("svg, polygon");
+    expect(elems.length).toEqual(2);
+    for (const el of elems) {
+      expect(el.namespaceURI).toBe("http://www.w3.org/2000/svg");
+    }
+  });
+
+  test("svg creates new block if it is within html -- 2", async () => {
+    class Test extends Component {
+      static template = xml`
+        <div>
+          <svg>
+            <polygon fill="#000000" points="0 0 4 4 8 0" transform="translate(5 7)"/>
+            <path t-if="hasPath" />
+          </svg>
+        </div>
+      `;
+      hasPath = true;
+    }
+    const fixture = makeTestFixture();
+    await mountComponent(Test, fixture);
+    const elems = fixture.querySelectorAll("svg, polygon, path");
+    expect(elems.length).toEqual(3);
+    for (const el of elems) {
+      expect(el.namespaceURI).toBe("http://www.w3.org/2000/svg");
+    }
+  });
 });

tests/compiler/t_out.test.ts

@@ -37,6 +37,26 @@ describe("t-out", () => {
     expect(renderToString(template, { var: "ok" })).toBe("<span>ok</span>");
   });
 
+  test("with a String class", () => {
+    const template = `<span><t t-out="var"/></span>`;
+    expect(renderToString(template, { var: new String("ok") })).toBe("<span>ok</span>");
+  });
+
+  test("with an extended String class", () => {
+    class LoveString extends String {
+      valueOf(): string {
+        return `<3 ${super.valueOf()} <3`;
+      }
+      toString(): string {
+        return this.valueOf();
+      }
+    }
+    const template = `<span><t t-out="var"/></span>`;
+    expect(renderToString(template, { var: new LoveString("ok") })).toBe(
+      "<span>&lt;3 ok &lt;3</span>"
+    );
+  });
+
   test("not escaping", () => {
     const template = `<div><t t-out="var"/></div>`;
     expect(renderToString(template, { var: markup("<ok></ok>") })).toBe("<div><ok></ok></div>");

tests/compiler/template_set.test.ts

@@ -24,6 +24,17 @@ describe("loading templates", () => {
     expect(context.renderToString("hey")).toBe("<div>jupiler</div>");
   });
 
+  test("addTemplates does not modify its xml document in place", () => {
+    const data = `<?xml version="1.0" encoding="UTF-8"?>
+      <templates id="template" xml:space="preserve"><div t-name="hey"><t t-esc="value"/></div></templates>`;
+    const xml = new DOMParser().parseFromString(data, "text/xml");
+    const context = new TestContext();
+    expect(xml.firstElementChild!.innerHTML).toBe(`<div t-name="hey"><t t-esc="value"/></div>`);
+    context.addTemplates(xml);
+    expect(context.renderToString("hey", { value: 123 })).toBe("<div>123</div>");
+    expect(xml.firstElementChild!.innerHTML).toBe(`<div t-name="hey"><t t-esc="value"/></div>`);
+  });
+
   test("can load a few templates from a xml string", () => {
     const data = `<?xml version="1.0" encoding="UTF-8"?>
       <templates id="template" xml:space="preserve">

tests/compiler/translation.test.ts

@@ -59,18 +59,20 @@ describe("translation support", () => {
     );
   });
 
-  test("can set translatable attributes", async () => {
+  test("can set and remove translatable attributes", async () => {
     class SomeComponent extends Component {
       static template = xml`
-        <div tomato="word" potato="word" title="word">text</div>
+        <div tomato="word" potato="word" title="word" label="word">text</div>
       `;
     }
 
     await mount(SomeComponent, fixture, {
       translateFn: (expr: string) => (expr === "word" ? "mot" : expr),
-      translatableAttributes: ["potato"],
+      translatableAttributes: ["potato", "-label"],
     });
-    expect(fixture.innerHTML).toBe('<div tomato="word" potato="mot" title="word">text</div>');
+    expect(fixture.innerHTML).toBe(
+      '<div tomato="word" potato="mot" title="mot" label="word">text</div>'
+    );
   });
 
   test("translation is done on the trimmed text, with extra spaces readded after", async () => {

tests/compiler/validation.test.ts

@@ -11,11 +11,12 @@ describe("basic validation", () => {
     expect(() => context.getTemplate("invalidname")).toThrow("Missing template");
   });
 
-  test("cannot add twice the same template", () => {
+  test("cannot add a different template with the same name", () => {
     const context = new TemplateSet();
-    expect(() => context.addTemplate("test", "<div/>", { allowDuplicate: true })).not.toThrow(
-      "already defined"
-    );
+    context.addTemplate("test", `<t/>`);
+    // Same template with the same name is fine
+    expect(() => context.addTemplate("test", "<t/>")).not.toThrow();
+    // Different template with the same name crashes
     expect(() => context.addTemplate("test", "<div/>")).toThrow("already defined");
   });
 

tests/components/__snapshots__/basics.test.ts.snap

@@ -6,7 +6,7 @@ exports[`basics GrandChild display is controlled by its GrandParent 1`] = `
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
-    let Comp1 = ctx['myComp'];
+    const Comp1 = ctx['myComp'];
     return toggler(Comp1, component(Comp1, {displayGrandChild: ctx['displayGrandChild']}, key + \`__1\`, node, ctx));
   }
 }"
@@ -49,9 +49,9 @@ exports[`basics Multi root component 1`] = `
   let block4 = createBlock(\`<span>2</span>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = block2();
-    let b3 = text(\`text\`);
-    let b4 = block4();
+    const b2 = block2();
+    const b3 = text(\`text\`);
+    const b4 = block4();
     return multi([b2, b3, b4]);
   }
 }"
@@ -81,6 +81,19 @@ exports[`basics a class component inside a class component, no external dom 2`]
 }"
 `;
 
+exports[`basics a component cannot be mounted in a detached node (even if node is detached later) 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block1 = createBlock(\`<div/>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    return block1();
+  }
+}"
+`;
+
 exports[`basics a component inside a component 1`] = `
 "function anonymous(bdom, helpers
 ) {
@@ -89,7 +102,7 @@ exports[`basics a component inside a component 1`] = `
   let block1 = createBlock(\`<span><block-child-0/></span>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    const b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -132,7 +145,7 @@ exports[`basics can handle empty props 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, {val: undefined}, key + \`__1\`, node, ctx);
+    const b2 = component(\`Child\`, {val: undefined}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -223,8 +236,8 @@ exports[`basics can mount a simple component with multiple roots 1`] = `
   let block3 = createBlock(\`<div/>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = block2();
-    let b3 = block3();
+    const b2 = block2();
+    const b3 = block3();
     return multi([b2, b3]);
   }
 }"
@@ -464,15 +477,15 @@ exports[`basics list of two sub components inside other nodes 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].blips);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].blips);;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`blip\`] = v_block2[i1];
-      let key1 = ctx['blip'].id;
-      let b4 = component(\`SubWidget\`, {}, key + \`__1__\${key1}\`, node, ctx);
-      let b5 = component(\`SubWidget\`, {}, key + \`__2__\${key1}\`, node, ctx);
+      const key1 = ctx['blip'].id;
+      const b4 = component(\`SubWidget\`, {}, key + \`__1__\${key1}\`, node, ctx);
+      const b5 = component(\`SubWidget\`, {}, key + \`__2__\${key1}\`, node, ctx);
       c_block2[i1] = withKey(block3([], [b4, b5]), key1);
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     return block1([], [b2]);
   }
 }"
@@ -547,9 +560,9 @@ exports[`basics reconciliation alg is not confused in some specific situation 1`
   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 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
     const tKey_1 = 4;
-    let b3 = toggler(tKey_1, component(\`Child\`, {}, tKey_1 + key + \`__2\`, node, ctx));
+    const b3 = toggler(tKey_1, component(\`Child\`, {}, tKey_1 + key + \`__2\`, node, ctx));
     return block1([], [b2, b3]);
   }
 }"
@@ -604,9 +617,9 @@ exports[`basics same t-keys in two different places 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     const tKey_1 = 1;
-    let b2 = toggler(tKey_1, component(\`Child\`, {blip: '1'}, tKey_1 + key + \`__1\`, node, ctx));
+    const b2 = toggler(tKey_1, component(\`Child\`, {blip: '1'}, tKey_1 + key + \`__1\`, node, ctx));
     const tKey_2 = 1;
-    let b3 = toggler(tKey_2, component(\`Child\`, {blip: '2'}, tKey_2 + key + \`__2\`, node, ctx));
+    const b3 = toggler(tKey_2, component(\`Child\`, {blip: '2'}, tKey_2 + key + \`__2\`, node, ctx));
     return block1([], [b2, b3]);
   }
 }"
@@ -939,8 +952,8 @@ exports[`basics two child components 1`] = `
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
-    let b3 = component(\`Child\`, {}, key + \`__2\`, node, ctx);
+    const b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    const b3 = component(\`Child\`, {}, key + \`__2\`, node, ctx);
     return multi([b2, b3]);
   }
 }"
@@ -968,7 +981,7 @@ exports[`basics update props of component without concrete own node 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     const tKey_1 = ctx['childProps'].key;
-    let b2 = toggler(tKey_1, component(\`Child\`, ctx['childProps'], tKey_1 + key + \`__1\`, node, ctx));
+    const b2 = toggler(tKey_1, component(\`Child\`, Object.assign({}, ctx['childProps']), tKey_1 + key + \`__1\`, node, ctx));
     return block1([], [b2]);
   }
 }"
@@ -981,7 +994,7 @@ exports[`basics update props of component without concrete own node 2`] = `
   
   return function template(ctx, node, key = \\"\\") {
     const tKey_1 = ctx['props'].subKey;
-    return toggler(tKey_1, component(\`Custom\`, {key: ctx['props'].key,subKey: ctx['props'].subKey}, tKey_1 + key + \`__1\`, node, ctx));
+    return toggler(tKey_1, component(\`Custom\`, {key: ctx['props'].key, subKey: ctx['props'].subKey}, tKey_1 + key + \`__1\`, node, ctx));
   }
 }"
 `;
@@ -1009,10 +1022,10 @@ exports[`basics updating a component with t-foreach as root 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['items']);
+    const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['items']);;
     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);
@@ -1058,16 +1071,16 @@ exports[`basics widget after a t-foreach 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(Array(2));
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(Array(2));;
     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'];
       c_block2[i1] = withKey(text(\`txt\`), key1);
     }
     ctx = ctx.__proto__;
-    let b2 = list(c_block2);
-    let b4 = component(\`SomeComponent\`, {}, key + \`__1\`, node, ctx);
+    const b2 = list(c_block2);
+    const b4 = component(\`SomeComponent\`, {}, key + \`__1\`, node, ctx);
     return block1([], [b2, b4]);
   }
 }"
@@ -1174,7 +1187,7 @@ exports[`support svg components add proper namespace to svg 1`] = `
   let block1 = createBlock(\`<svg block-ns=\\"http://www.w3.org/2000/svg\\"><block-child-0/></svg>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`GComp\`, {}, key + \`__1\`, node, ctx);
+    const b2 = component(\`GComp\`, {}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1203,20 +1216,34 @@ exports[`t-out in components can render list of t-out  1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].items);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].items);;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`item\`] = v_block2[i1];
-      let key1 = ctx['item'];
-      let b4 = text(ctx['item']);
-      let b5 = safeOutput(ctx['item']);
+      const key1 = ctx['item'];
+      const b4 = text(ctx['item']);
+      const b5 = safeOutput(ctx['item']);
       c_block2[i1] = withKey(multi([b4, b5]), key1);
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     return block1([], [b2]);
   }
 }"
 `;
 
+exports[`t-out in components can switch the contents of two t-out repeatedly 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { safeOutput } = helpers;
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = safeOutput(ctx['state'].a);
+    const b3 = safeOutput(ctx['state'].b);
+    return multi([b2, b3]);
+  }
+}"
+`;
+
 exports[`t-out in components update properly on state changes 1`] = `
 "function anonymous(bdom, helpers
 ) {
@@ -1226,7 +1253,7 @@ exports[`t-out in components update properly on state changes 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = safeOutput(ctx['state'].value);
+    const b2 = safeOutput(ctx['state'].value);
     return block1([], [b2]);
   }
 }"

tests/components/__snapshots__/concurrency.test.ts.snap

@@ -7,16 +7,16 @@ exports[`Cascading renders after microtaskTick 1`] = `
   let { prepareList, withKey } = helpers;
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
-    let b3 = text(\` _ \`);
+    const b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    const b3 = text(\` _ \`);
     ctx = Object.create(ctx);
-    const [k_block4, v_block4, l_block4, c_block4] = prepareList(ctx['state']);
+    const [k_block4, v_block4, l_block4, c_block4] = prepareList(ctx['state']);;
     for (let i1 = 0; i1 < l_block4; i1++) {
       ctx[\`elem\`] = v_block4[i1];
-      let key1 = ctx['elem'].id;
+      const key1 = ctx['elem'].id;
       c_block4[i1] = withKey(text(ctx['elem'].id), key1);
     }
-    let b4 = list(c_block4);
+    const b4 = list(c_block4);
     return multi([b2, b3, b4]);
   }
 }"
@@ -30,10 +30,10 @@ exports[`Cascading renders after microtaskTick 2`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['state']);
+    const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['state']);;
     for (let i1 = 0; i1 < l_block1; i1++) {
       ctx[\`elem\`] = v_block1[i1];
-      let key1 = ctx['elem'].id;
+      const key1 = ctx['elem'].id;
       c_block1[i1] = withKey(component(\`Element\`, {id: ctx['elem'].id}, key + \`__1__\${key1}\`, node, ctx), key1);
     }
     return list(c_block1);
@@ -52,6 +52,50 @@ exports[`Cascading renders after microtaskTick 3`] = `
 }"
 `;
 
+exports[`another scenario with delayed rendering 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    let b2,b3;
+    b2 = text(\`A\`);
+    if (ctx['state'].value<15) {
+      b3 = component(\`B\`, {value: ctx['state'].value}, key + \`__1\`, node, ctx);
+    }
+    return multi([b2, b3]);
+  }
+}"
+`;
+
+exports[`another scenario with delayed rendering 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = text(ctx['props'].value);
+    const b3 = component(\`C\`, {}, key + \`__1\`, node, ctx);
+    return multi([b2, b3]);
+  }
+}"
+`;
+
+exports[`another scenario with delayed rendering 3`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block1 = createBlock(\`<button block-handler-0=\\"click\\"><block-text-1/></button>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let hdlr1 = [ctx['increment'], ctx];
+    let txt1 = ctx['state'].val;
+    return block1([hdlr1, txt1]);
+  }
+}"
+`;
+
 exports[`async rendering destroying a widget before start is over 1`] = `
 "function anonymous(bdom, helpers
 ) {
@@ -169,7 +213,7 @@ exports[`concurrent renderings scenario 1 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`ComponentB\`, {fromA: ctx['state'].fromA}, key + \`__1\`, node, ctx);
+    const b2 = component(\`ComponentB\`, {fromA: ctx['state'].fromA}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -183,7 +227,7 @@ exports[`concurrent renderings scenario 1 2`] = `
   let block1 = createBlock(\`<p><block-child-0/></p>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`ComponentC\`, {fromA: ctx['props'].fromA,fromB: ctx['state'].fromB}, key + \`__1\`, node, ctx);
+    const b2 = component(\`ComponentC\`, {fromA: ctx['props'].fromA, fromB: ctx['state'].fromB}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -213,7 +257,7 @@ exports[`concurrent renderings scenario 2 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     let txt1 = ctx['state'].fromA;
-    let b2 = component(\`ComponentB\`, {fromA: ctx['state'].fromA}, key + \`__1\`, node, ctx);
+    const b2 = component(\`ComponentB\`, {fromA: ctx['state'].fromA}, key + \`__1\`, node, ctx);
     return block1([txt1], [b2]);
   }
 }"
@@ -227,7 +271,7 @@ exports[`concurrent renderings scenario 2 2`] = `
   let block1 = createBlock(\`<p><block-child-0/></p>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`ComponentC\`, {fromA: ctx['props'].fromA,fromB: ctx['state'].fromB}, key + \`__1\`, node, ctx);
+    const b2 = component(\`ComponentC\`, {fromA: ctx['props'].fromA, fromB: ctx['state'].fromB}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -256,7 +300,7 @@ exports[`concurrent renderings scenario 2bis 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`ComponentB\`, {fromA: ctx['state'].fromA}, key + \`__1\`, node, ctx);
+    const b2 = component(\`ComponentB\`, {fromA: ctx['state'].fromA}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -270,7 +314,7 @@ exports[`concurrent renderings scenario 2bis 2`] = `
   let block1 = createBlock(\`<p><block-child-0/></p>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`ComponentC\`, {fromA: ctx['props'].fromA,fromB: ctx['state'].fromB}, key + \`__1\`, node, ctx);
+    const b2 = component(\`ComponentC\`, {fromA: ctx['props'].fromA, fromB: ctx['state'].fromB}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -299,7 +343,7 @@ exports[`concurrent renderings scenario 3 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`ComponentB\`, {fromA: ctx['state'].fromA}, key + \`__1\`, node, ctx);
+    const b2 = component(\`ComponentB\`, {fromA: ctx['state'].fromA}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -313,7 +357,7 @@ exports[`concurrent renderings scenario 3 2`] = `
   let block1 = createBlock(\`<p><block-child-0/></p>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`ComponentC\`, {fromA: ctx['props'].fromA}, key + \`__1\`, node, ctx);
+    const b2 = component(\`ComponentC\`, {fromA: ctx['props'].fromA}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -327,7 +371,7 @@ exports[`concurrent renderings scenario 3 3`] = `
   let block1 = createBlock(\`<span><block-child-0/></span>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`ComponentD\`, {fromA: ctx['props'].fromA,fromC: ctx['state'].fromC}, key + \`__1\`, node, ctx);
+    const b2 = component(\`ComponentD\`, {fromA: ctx['props'].fromA, fromC: ctx['state'].fromC}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -356,7 +400,7 @@ exports[`concurrent renderings scenario 4 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`ComponentB\`, {fromA: ctx['state'].fromA}, key + \`__1\`, node, ctx);
+    const b2 = component(\`ComponentB\`, {fromA: ctx['state'].fromA}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -370,7 +414,7 @@ exports[`concurrent renderings scenario 4 2`] = `
   let block1 = createBlock(\`<p><block-child-0/></p>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`ComponentC\`, {fromA: ctx['props'].fromA}, key + \`__1\`, node, ctx);
+    const b2 = component(\`ComponentC\`, {fromA: ctx['props'].fromA}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -384,7 +428,7 @@ exports[`concurrent renderings scenario 4 3`] = `
   let block1 = createBlock(\`<span><block-child-0/></span>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`ComponentD\`, {fromA: ctx['props'].fromA,fromC: ctx['state'].fromC}, key + \`__1\`, node, ctx);
+    const b2 = component(\`ComponentD\`, {fromA: ctx['props'].fromA, fromC: ctx['state'].fromC}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -413,7 +457,7 @@ exports[`concurrent renderings scenario 5 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`ComponentB\`, {fromA: ctx['state'].fromA}, key + \`__1\`, node, ctx);
+    const b2 = component(\`ComponentB\`, {fromA: ctx['state'].fromA}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -441,7 +485,7 @@ exports[`concurrent renderings scenario 6 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`ComponentB\`, {fromA: ctx['state'].fromA}, key + \`__1\`, node, ctx);
+    const b2 = component(\`ComponentB\`, {fromA: ctx['state'].fromA}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -469,7 +513,7 @@ exports[`concurrent renderings scenario 7 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`ComponentB\`, {fromA: ctx['state'].fromA}, key + \`__1\`, node, ctx);
+    const b2 = component(\`ComponentB\`, {fromA: ctx['state'].fromA}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -498,7 +542,7 @@ exports[`concurrent renderings scenario 8 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`ComponentB\`, {fromA: ctx['state'].fromA}, key + \`__1\`, node, ctx);
+    const b2 = component(\`ComponentB\`, {fromA: ctx['state'].fromA}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -528,8 +572,8 @@ exports[`concurrent renderings scenario 9 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     let txt1 = ctx['state'].fromA;
-    let b2 = component(\`ComponentB\`, {fromA: ctx['state'].fromA}, key + \`__1\`, node, ctx);
-    let b3 = component(\`ComponentC\`, {fromA: ctx['state'].fromA}, key + \`__2\`, node, ctx);
+    const b2 = component(\`ComponentB\`, {fromA: ctx['state'].fromA}, key + \`__1\`, node, ctx);
+    const b3 = component(\`ComponentC\`, {fromA: ctx['state'].fromA}, key + \`__2\`, node, ctx);
     return block1([txt1], [b2, b3]);
   }
 }"
@@ -557,7 +601,7 @@ exports[`concurrent renderings scenario 9 3`] = `
   let block1 = createBlock(\`<p><block-child-0/></p>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`ComponentD\`, {fromA: ctx['props'].fromA,fromC: ctx['state'].fromC}, key + \`__1\`, node, ctx);
+    const b2 = component(\`ComponentD\`, {fromA: ctx['props'].fromA, fromC: ctx['state'].fromC}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -586,7 +630,7 @@ exports[`concurrent renderings scenario 10 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`ComponentB\`, {value: ctx['state'].value}, key + \`__1\`, node, ctx);
+    const b2 = component(\`ComponentB\`, {value: ctx['state'].value}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -631,7 +675,7 @@ exports[`concurrent renderings scenario 11 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, {val: ctx['state'].valA}, key + \`__1\`, node, ctx);
+    const b2 = component(\`Child\`, {val: ctx['state'].valA}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -660,7 +704,7 @@ exports[`concurrent renderings scenario 12 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, {val: ctx['val']}, key + \`__1\`, node, ctx);
+    const b2 = component(\`Child\`, {val: ctx['val']}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -720,7 +764,7 @@ exports[`concurrent renderings scenario 14 1`] = `
   let block1 = createBlock(\`<p><block-child-0/></p>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`B\`, {fromA: ctx['state'].fromA}, key + \`__1\`, node, ctx);
+    const b2 = component(\`B\`, {fromA: ctx['state'].fromA}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -734,7 +778,7 @@ exports[`concurrent renderings scenario 14 2`] = `
   let block1 = createBlock(\`<p><block-child-0/></p>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`C\`, {fromB: ctx['state'].fromB,fromA: ctx['props'].fromA}, key + \`__1\`, node, ctx);
+    const b2 = component(\`C\`, {fromB: ctx['state'].fromB, fromA: ctx['props'].fromA}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -764,7 +808,7 @@ exports[`concurrent renderings scenario 15 1`] = `
   let block1 = createBlock(\`<p><block-child-0/></p>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`B\`, {fromA: ctx['state'].fromA}, key + \`__1\`, node, ctx);
+    const b2 = component(\`B\`, {fromA: ctx['state'].fromA}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -778,7 +822,7 @@ exports[`concurrent renderings scenario 15 2`] = `
   let block1 = createBlock(\`<p><block-child-0/></p>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`C\`, {fromB: ctx['state'].fromB,fromA: ctx['props'].fromA}, key + \`__1\`, node, ctx);
+    const b2 = component(\`C\`, {fromB: ctx['state'].fromB, fromA: ctx['props'].fromA}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -817,7 +861,7 @@ exports[`concurrent renderings scenario 16 2`] = `
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
-    return component(\`C\`, {fromB: ctx['state'].fromB,fromA: ctx['props'].fromA}, key + \`__1\`, node, ctx);
+    return component(\`C\`, {fromB: ctx['state'].fromB, fromA: ctx['props'].fromA}, key + \`__1\`, node, ctx);
   }
 }"
 `;
@@ -1008,9 +1052,9 @@ exports[`delay willUpdateProps 2`] = `
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = text(ctx['props'].value);
-    let b3 = text(\`_\`);
-    let b4 = text(ctx['state'].int);
+    const b2 = text(ctx['props'].value);
+    const b3 = text(\`_\`);
+    const b4 = text(ctx['state'].int);
     return multi([b2, b3, b4]);
   }
 }"
@@ -1033,8 +1077,8 @@ exports[`delay willUpdateProps with rendering grandchild 2`] = `
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`DelayedChild\`, {value: ctx['props'].state.value}, key + \`__1\`, node, ctx);
-    let b3 = component(\`ReactiveChild\`, {}, key + \`__2\`, node, ctx);
+    const b2 = component(\`DelayedChild\`, {value: ctx['props'].state.value}, key + \`__1\`, node, ctx);
+    const b3 = component(\`ReactiveChild\`, {}, key + \`__2\`, node, ctx);
     return multi([b2, b3]);
   }
 }"
@@ -1046,9 +1090,9 @@ exports[`delay willUpdateProps with rendering grandchild 3`] = `
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = text(ctx['props'].value);
-    let b3 = text(\`_\`);
-    let b4 = text(ctx['state'].int);
+    const b2 = text(ctx['props'].value);
+    const b3 = text(\`_\`);
+    const b4 = text(ctx['state'].int);
     return multi([b2, b3, b4]);
   }
 }"
@@ -1067,6 +1111,364 @@ exports[`delay willUpdateProps with rendering grandchild 4`] = `
 }"
 `;
 
+exports[`delayed fiber does not get rendered if it was cancelled 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = text(\`A\`);
+    const b3 = component(\`B\`, {}, key + \`__1\`, node, ctx);
+    return multi([b2, b3]);
+  }
+}"
+`;
+
+exports[`delayed fiber does not get rendered if it was cancelled 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = text(\`B\`);
+    const b3 = component(\`C\`, {}, key + \`__1\`, node, ctx);
+    return multi([b2, b3]);
+  }
+}"
+`;
+
+exports[`delayed fiber does not get rendered if it was cancelled 3`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = text(\`C\`);
+    const b3 = component(\`D\`, {}, key + \`__1\`, node, ctx);
+    return multi([b2, b3]);
+  }
+}"
+`;
+
+exports[`delayed fiber does not get rendered if it was cancelled 4`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return text(\`D\`);
+  }
+}"
+`;
+
+exports[`delayed rendering, but then initial rendering is cancelled by yet another render 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return component(\`B\`, {value: ctx['state'].value}, key + \`__1\`, node, ctx);
+  }
+}"
+`;
+
+exports[`delayed rendering, but then initial rendering is cancelled by yet another render 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return component(\`C\`, {value: ctx['state'].someValue+ctx['props'].value}, key + \`__1\`, node, ctx);
+  }
+}"
+`;
+
+exports[`delayed rendering, but then initial rendering is cancelled by yet another render 3`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block3 = createBlock(\`<p><block-text-0/></p>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = component(\`D\`, {}, key + \`__1\`, node, ctx);
+    let txt1 = ctx['props'].value;
+    const b3 = block3([txt1]);
+    return multi([b2, b3]);
+  }
+}"
+`;
+
+exports[`delayed rendering, but then initial rendering is cancelled by yet another render 4`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block1 = createBlock(\`<button block-handler-0=\\"click\\"><block-text-1/></button>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let hdlr1 = [ctx['increment'], ctx];
+    let txt1 = ctx['state'].val;
+    return block1([hdlr1, txt1]);
+  }
+}"
+`;
+
+exports[`delayed rendering, destruction, stuff happens 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = text(\`A\`);
+    const b3 = component(\`B\`, {value: ctx['state'].value}, key + \`__1\`, node, ctx);
+    return multi([b2, b3]);
+  }
+}"
+`;
+
+exports[`delayed rendering, destruction, stuff happens 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    let b2,b3;
+    b2 = text(\`B\`);
+    if (ctx['state'].hasChild) {
+      b3 = component(\`C\`, {value: ctx['state'].someValue+ctx['props'].value}, key + \`__1\`, node, ctx);
+    }
+    return multi([b2, b3]);
+  }
+}"
+`;
+
+exports[`delayed rendering, destruction, stuff happens 3`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block4 = createBlock(\`<p><block-text-0/></p>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = text(\`C\`);
+    const b3 = component(\`D\`, {}, key + \`__1\`, node, ctx);
+    let txt1 = ctx['props'].value;
+    const b4 = block4([txt1]);
+    return multi([b2, b3, b4]);
+  }
+}"
+`;
+
+exports[`delayed rendering, destruction, stuff happens 4`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block3 = createBlock(\`<button block-handler-0=\\"click\\"><block-text-1/></button>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = text(\`D\`);
+    let hdlr1 = [ctx['increment'], ctx];
+    let txt1 = ctx['state'].val;
+    const b3 = block3([hdlr1, txt1]);
+    return multi([b2, b3]);
+  }
+}"
+`;
+
+exports[`delayed rendering, reusing fiber and stuff 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return component(\`B\`, {value: ctx['state'].value}, key + \`__1\`, node, ctx);
+  }
+}"
+`;
+
+exports[`delayed rendering, reusing fiber and stuff 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = text(ctx['props'].value);
+    const b3 = component(\`C\`, {}, key + \`__1\`, node, ctx);
+    return multi([b2, b3]);
+  }
+}"
+`;
+
+exports[`delayed rendering, reusing fiber and stuff 3`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block1 = createBlock(\`<button block-handler-0=\\"click\\"><block-text-1/></button>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let hdlr1 = [ctx['increment'], ctx];
+    let txt1 = ctx['state'].val;
+    return block1([hdlr1, txt1]);
+  }
+}"
+`;
+
+exports[`delayed rendering, reusing fiber then component is destroyed and  stuff 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    let b2,b3;
+    b2 = text(\`A\`);
+    if (ctx['state'].value<15) {
+      b3 = component(\`B\`, {value: ctx['state'].value}, key + \`__1\`, node, ctx);
+    }
+    return multi([b2, b3]);
+  }
+}"
+`;
+
+exports[`delayed rendering, reusing fiber then component is destroyed and  stuff 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = text(ctx['props'].value);
+    const b3 = component(\`C\`, {}, key + \`__1\`, node, ctx);
+    return multi([b2, b3]);
+  }
+}"
+`;
+
+exports[`delayed rendering, reusing fiber then component is destroyed and  stuff 3`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block1 = createBlock(\`<button block-handler-0=\\"click\\"><block-text-1/></button>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let hdlr1 = [ctx['increment'], ctx];
+    let txt1 = ctx['state'].val;
+    return block1([hdlr1, txt1]);
+  }
+}"
+`;
+
+exports[`delayed rendering, then component is destroyed and  stuff 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return component(\`B\`, {value: ctx['state'].value}, key + \`__1\`, node, ctx);
+  }
+}"
+`;
+
+exports[`delayed rendering, then component is destroyed and  stuff 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    let b2,b3;
+    b2 = text(ctx['props'].value);
+    if (ctx['props'].value<10) {
+      b3 = component(\`C\`, {}, key + \`__1\`, node, ctx);
+    }
+    return multi([b2, b3]);
+  }
+}"
+`;
+
+exports[`delayed rendering, then component is destroyed and  stuff 3`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block1 = createBlock(\`<button block-handler-0=\\"click\\"><block-text-1/></button>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let hdlr1 = [ctx['increment'], ctx];
+    let txt1 = ctx['state'].val;
+    return block1([hdlr1, txt1]);
+  }
+}"
+`;
+
+exports[`destroyed component causes other soon to be destroyed component to rerender, weird stuff happens 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    let b2,b3;
+    b2 = text(\` A \`);
+    if (ctx['state'].flag) {
+      const b4 = component(\`B\`, {value: ctx['state'].valueB}, key + \`__1\`, node, ctx);
+      const b5 = component(\`C\`, {value: ctx['state'].valueC}, key + \`__2\`, node, ctx);
+      b3 = multi([b4, b5]);
+    }
+    return multi([b2, b3]);
+  }
+}"
+`;
+
+exports[`destroyed component causes other soon to be destroyed component to rerender, weird stuff happens 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return text(ctx['props'].value);
+  }
+}"
+`;
+
+exports[`destroyed component causes other soon to be destroyed component to rerender, weird stuff happens 3`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return text(ctx['state'].val+ctx['props'].value);
+  }
+}"
+`;
+
+exports[`destroying/recreating a subcomponent, other scenario 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    let b2,b3;
+    b2 = text(\`parent\`);
+    if (ctx['state'].hasChild) {
+      b3 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    }
+    return multi([b2, b3]);
+  }
+}"
+`;
+
+exports[`destroying/recreating a subcomponent, other scenario 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return text(\`child\`);
+  }
+}"
+`;
+
 exports[`destroying/recreating a subwidget with different props (if start is not over) 1`] = `
 "function anonymous(bdom, helpers
 ) {
@@ -1145,7 +1547,7 @@ exports[`properly behave when destroyed/unmounted while rendering  2`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`SubChild\`, {}, key + \`__1\`, node, ctx);
+    const b2 = component(\`SubChild\`, {val: ctx['props'].val}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1195,6 +1597,92 @@ exports[`rendering component again in next microtick 2`] = `
 }"
 `;
 
+exports[`rendering parent twice, with different props on child and stuff 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return component(\`Child\`, {value: ctx['state'].value}, key + \`__1\`, node, ctx);
+  }
+}"
+`;
+
+exports[`rendering parent twice, with different props on child and stuff 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return text(ctx['props'].value);
+  }
+}"
+`;
+
+exports[`renderings, destruction, patch, stuff, ... yet another variation 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = text(\`A\`);
+    const b3 = component(\`B\`, {value: ctx['state'].value}, key + \`__1\`, node, ctx);
+    const b4 = component(\`D\`, {}, key + \`__2\`, node, ctx);
+    return multi([b2, b3, b4]);
+  }
+}"
+`;
+
+exports[`renderings, destruction, patch, stuff, ... yet another variation 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    let b2,b3;
+    b2 = text(\`B\`);
+    if (ctx['props'].value===33) {
+      b3 = component(\`C\`, {}, key + \`__1\`, node, ctx);
+    }
+    return multi([b2, b3]);
+  }
+}"
+`;
+
+exports[`renderings, destruction, patch, stuff, ... yet another variation 3`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block3 = createBlock(\`<p block-handler-0=\\"click\\"><block-text-1/></p>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = text(\`D\`);
+    let hdlr1 = [ctx['increment'], ctx];
+    let txt1 = ctx['state'].val;
+    const b3 = block3([hdlr1, txt1]);
+    return multi([b2, b3]);
+  }
+}"
+`;
+
+exports[`renderings, destruction, patch, stuff, ... yet another variation 4`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block3 = createBlock(\`<span block-handler-0=\\"click\\"><block-text-1/></span>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = text(\`C\`);
+    let hdlr1 = [ctx['increment'], ctx];
+    let txt1 = ctx['state'].val;
+    const b3 = block3([hdlr1, txt1]);
+    return multi([b2, b3]);
+  }
+}"
+`;
+
 exports[`t-foreach with dynamic async component 1`] = `
 "function anonymous(bdom, helpers
 ) {
@@ -1203,14 +1691,14 @@ exports[`t-foreach with dynamic async component 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['list']);
+    const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['list']);;
     for (let i1 = 0; i1 < l_block1; i1++) {
       ctx[\`arr\`] = v_block1[i1];
       ctx[\`arr_index\`] = i1;
-      let key1 = ctx['arr_index'];
+      const key1 = ctx['arr_index'];
       let b3;
       if (ctx['arr']) {
-        let Comp1 = ctx['myComp'];
+        const Comp1 = ctx['myComp'];
         b3 = toggler(Comp1, component(Comp1, {key: ctx['arr'][0]}, key + \`__1__\${key1}\`, node, ctx));
       }
       c_block1[i1] = withKey(multi([b3]), key1);
@@ -1243,8 +1731,8 @@ exports[`t-key on dom node having a component 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     const tKey_1 = ctx['key'];
-    let Comp1 = ctx['myComp'];
-    let b2 = toggler(tKey_1, toggler(Comp1, component(Comp1, {key: ctx['key']}, tKey_1 + key + \`__1\`, node, ctx)));
+    const Comp1 = ctx['myComp'];
+    const b2 = toggler(tKey_1, toggler(Comp1, component(Comp1, {key: ctx['key']}, tKey_1 + key + \`__1\`, node, ctx)));
     return toggler(tKey_1, block1([], [b2]));
   }
 }"
@@ -1268,7 +1756,7 @@ exports[`t-key on dynamic async component (toggler is never patched) 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     const tKey_1 = ctx['key'];
-    let Comp1 = ctx['myComp'];
+    const Comp1 = ctx['myComp'];
     return toggler(tKey_1, toggler(Comp1, component(Comp1, {key: ctx['key']}, tKey_1 + key + \`__1\`, node, ctx)));
   }
 }"
@@ -1351,7 +1839,7 @@ exports[`update a sub-component twice in the same frame 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`ChildA\`, {val: ctx['state'].valA}, key + \`__1\`, node, ctx);
+    const b2 = component(\`ChildA\`, {val: ctx['state'].valA}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1379,7 +1867,7 @@ exports[`update a sub-component twice in the same frame, 2 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`ChildA\`, {val: ctx['state'].valA}, key + \`__1\`, node, ctx);
+    const b2 = component(\`ChildA\`, {val: ctx['state'].valA}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"

tests/components/__snapshots__/error_handling.test.ts.snap

@@ -1,5 +1,18 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`basics display a nice error if it cannot find component (in dev mode) 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    const props1 = {};
+    helpers.validateProps(\`SomeMispelledComponent\`, props1, ctx);
+    return component(\`SomeMispelledComponent\`, props1, key + \`__1\`, node, ctx);
+  }
+}"
+`;
+
 exports[`basics display a nice error if it cannot find component 1`] = `
 "function anonymous(bdom, helpers
 ) {
@@ -19,7 +32,7 @@ exports[`basics no component catching error lead to full app destruction 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`ErrorComponent\`, {flag: ctx['state'].flag}, key + \`__1\`, node, ctx);
+    const b2 = component(\`ErrorComponent\`, {flag: ctx['state'].flag}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -72,10 +85,80 @@ exports[`basics simple catchError 2`] = `
 }"
 `;
 
+exports[`can catch errors an error in onWillDestroy 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    let b2,b3;
+    b2 = text(ctx['state'].value);
+    if (ctx['state'].hasChild) {
+      b3 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    }
+    return multi([b2, b3]);
+  }
+}"
+`;
+
+exports[`can catch errors an error in onWillDestroy 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block1 = createBlock(\`<div>abc</div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    return block1();
+  }
+}"
+`;
+
+exports[`can catch errors an error in onWillDestroy, variation 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    let b2,b3;
+    b2 = text(ctx['state'].value);
+    if (ctx['state'].hasChild) {
+      b3 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    }
+    return multi([b2, b3]);
+  }
+}"
+`;
+
+exports[`can catch errors an error in onWillDestroy, variation 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block1 = createBlock(\`<div>abc</div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    return block1();
+  }
+}"
+`;
+
+exports[`can catch errors calling a hook outside setup should crash 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return text(ctx['state'].value);
+  }
+}"
+`;
+
 exports[`can catch errors can catch an error in a component render function 1`] = `
 "function anonymous(bdom, helpers
 ) {
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { markRaw } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
@@ -84,7 +167,7 @@ exports[`can catch errors can catch an error in a component render function 1`]
   }
   
   return function template(ctx, node, key = \\"\\") {
-    let b3 = component(\`ErrorBoundary\`, {slots: {'default': {__render: slot1, __ctx: ctx}}}, key + \`__2\`, node, ctx);
+    const b3 = component(\`ErrorBoundary\`, {slots: markRaw({'default': {__render: slot1, __ctx: ctx}})}, key + \`__2\`, node, ctx);
     return block1([], [b3]);
   }
 }"
@@ -103,7 +186,7 @@ exports[`can catch errors can catch an error in a component render function 2`]
     if (ctx['state'].error) {
       b2 = text(\`Error handled\`);
     } else {
-      b3 = callSlot(ctx, node, key, 'default', false, {});
+      b3 = callSlot(ctx, node, key, 'default', false, null);
     }
     return block1([], [b2, b3]);
   }
@@ -128,6 +211,7 @@ exports[`can catch errors can catch an error in the constructor call of a compon
 "function anonymous(bdom, helpers
 ) {
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { markRaw } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
@@ -136,7 +220,7 @@ exports[`can catch errors can catch an error in the constructor call of a compon
   }
   
   return function template(ctx, node, key = \\"\\") {
-    let b3 = component(\`ErrorBoundary\`, {slots: {'default': {__render: slot1, __ctx: ctx}}}, key + \`__2\`, node, ctx);
+    const b3 = component(\`ErrorBoundary\`, {slots: markRaw({'default': {__render: slot1, __ctx: ctx}})}, key + \`__2\`, node, ctx);
     return block1([], [b3]);
   }
 }"
@@ -155,7 +239,7 @@ exports[`can catch errors can catch an error in the constructor call of a compon
     if (ctx['state'].error) {
       b2 = text(\`Error handled\`);
     } else {
-      b3 = callSlot(ctx, node, key, 'default', false, {});
+      b3 = callSlot(ctx, node, key, 'default', false, null);
     }
     return block1([], [b2, b3]);
   }
@@ -166,17 +250,18 @@ exports[`can catch errors can catch an error in the constructor call of a compon
 "function anonymous(bdom, helpers
 ) {
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { markRaw } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   function slot1(ctx, node, key = \\"\\") {
-    let b3 = component(\`ClassicCompoent\`, {}, key + \`__1\`, node, ctx);
-    let b4 = component(\`ErrorComponent\`, {}, key + \`__2\`, node, ctx);
+    const b3 = component(\`ClassicCompoent\`, {}, key + \`__1\`, node, ctx);
+    const b4 = component(\`ErrorComponent\`, {}, key + \`__2\`, node, ctx);
     return multi([b3, b4]);
   }
   
   return function template(ctx, node, key = \\"\\") {
-    let b5 = component(\`ErrorBoundary\`, {slots: {'default': {__render: slot1, __ctx: ctx}}}, key + \`__3\`, node, ctx);
+    const b5 = component(\`ErrorBoundary\`, {slots: markRaw({'default': {__render: slot1, __ctx: ctx}})}, key + \`__3\`, node, ctx);
     return block1([], [b5]);
   }
 }"
@@ -195,7 +280,7 @@ exports[`can catch errors can catch an error in the constructor call of a compon
     if (ctx['state'].error) {
       b2 = text(\`Error handled\`);
     } else {
-      b3 = callSlot(ctx, node, key, 'default', false, {});
+      b3 = callSlot(ctx, node, key, 'default', false, null);
     }
     return block1([], [b2, b3]);
   }
@@ -245,6 +330,7 @@ exports[`can catch errors can catch an error in the initial call of a component
 "function anonymous(bdom, helpers
 ) {
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { markRaw } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
@@ -253,7 +339,7 @@ exports[`can catch errors can catch an error in the initial call of a component
   }
   
   return function template(ctx, node, key = \\"\\") {
-    let b3 = component(\`ErrorBoundary\`, {slots: {'default': {__render: slot1, __ctx: ctx}}}, key + \`__2\`, node, ctx);
+    const b3 = component(\`ErrorBoundary\`, {slots: markRaw({'default': {__render: slot1, __ctx: ctx}})}, key + \`__2\`, node, ctx);
     return block1([], [b3]);
   }
 }"
@@ -272,7 +358,7 @@ exports[`can catch errors can catch an error in the initial call of a component
     if (ctx['state'].error) {
       b2 = text(\`Error handled\`);
     } else {
-      b3 = callSlot(ctx, node, key, 'default', false, {});
+      b3 = callSlot(ctx, node, key, 'default', false, null);
     }
     return block1([], [b2, b3]);
   }
@@ -297,6 +383,7 @@ exports[`can catch errors can catch an error in the initial call of a component
 "function anonymous(bdom, helpers
 ) {
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { markRaw } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
@@ -307,7 +394,7 @@ exports[`can catch errors can catch an error in the initial call of a component
   return function template(ctx, node, key = \\"\\") {
     let b3;
     if (ctx['state'].flag) {
-      b3 = component(\`ErrorBoundary\`, {slots: {'default': {__render: slot1, __ctx: ctx}}}, key + \`__2\`, node, ctx);
+      b3 = component(\`ErrorBoundary\`, {slots: markRaw({'default': {__render: slot1, __ctx: ctx}})}, key + \`__2\`, node, ctx);
     }
     return block1([], [b3]);
   }
@@ -327,7 +414,7 @@ exports[`can catch errors can catch an error in the initial call of a component
     if (ctx['state'].error) {
       b2 = text(\`Error handled\`);
     } else {
-      b3 = callSlot(ctx, node, key, 'default', false, {});
+      b3 = callSlot(ctx, node, key, 'default', false, null);
     }
     return block1([], [b2, b3]);
   }
@@ -367,7 +454,7 @@ exports[`can catch errors can catch an error in the mounted call (in child of ch
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`C\`, {}, key + \`__1\`, node, ctx);
+    const b2 = component(\`C\`, {}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -441,6 +528,7 @@ exports[`can catch errors can catch an error in the mounted call 1`] = `
 "function anonymous(bdom, helpers
 ) {
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { markRaw } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
@@ -449,7 +537,7 @@ exports[`can catch errors can catch an error in the mounted call 1`] = `
   }
   
   return function template(ctx, node, key = \\"\\") {
-    let b3 = component(\`ErrorBoundary\`, {slots: {'default': {__render: slot1, __ctx: ctx}}}, key + \`__2\`, node, ctx);
+    const b3 = component(\`ErrorBoundary\`, {slots: markRaw({'default': {__render: slot1, __ctx: ctx}})}, key + \`__2\`, node, ctx);
     return block1([], [b3]);
   }
 }"
@@ -468,7 +556,7 @@ exports[`can catch errors can catch an error in the mounted call 2`] = `
     if (ctx['state'].error) {
       b2 = text(\`Error handled\`);
     } else {
-      b3 = callSlot(ctx, node, key, 'default', false, {});
+      b3 = callSlot(ctx, node, key, 'default', false, null);
     }
     return block1([], [b2, b3]);
   }
@@ -492,6 +580,7 @@ exports[`can catch errors can catch an error in the willPatch call 1`] = `
 "function anonymous(bdom, helpers
 ) {
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { markRaw } = helpers;
   
   let block1 = createBlock(\`<div><span><block-text-0/></span><block-child-0/></div>\`);
   
@@ -501,7 +590,7 @@ exports[`can catch errors can catch an error in the willPatch call 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     let txt1 = ctx['state'].message;
-    let b3 = component(\`ErrorBoundary\`, {slots: {'default': {__render: slot1, __ctx: ctx}}}, key + \`__2\`, node, ctx);
+    const b3 = component(\`ErrorBoundary\`, {slots: markRaw({'default': {__render: slot1, __ctx: ctx}})}, key + \`__2\`, node, ctx);
     return block1([txt1], [b3]);
   }
 }"
@@ -520,7 +609,7 @@ exports[`can catch errors can catch an error in the willPatch call 2`] = `
     if (ctx['state'].error) {
       b2 = text(\`Error handled\`);
     } else {
-      b3 = callSlot(ctx, node, key, 'default', false, {});
+      b3 = callSlot(ctx, node, key, 'default', false, null);
     }
     return block1([], [b2, b3]);
   }
@@ -545,6 +634,7 @@ exports[`can catch errors can catch an error in the willStart call 1`] = `
 "function anonymous(bdom, helpers
 ) {
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { markRaw } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
@@ -553,7 +643,7 @@ exports[`can catch errors can catch an error in the willStart call 1`] = `
   }
   
   return function template(ctx, node, key = \\"\\") {
-    let b3 = component(\`ErrorBoundary\`, {slots: {'default': {__render: slot1, __ctx: ctx}}}, key + \`__2\`, node, ctx);
+    const b3 = component(\`ErrorBoundary\`, {slots: markRaw({'default': {__render: slot1, __ctx: ctx}})}, key + \`__2\`, node, ctx);
     return block1([], [b3]);
   }
 }"
@@ -572,7 +662,7 @@ exports[`can catch errors can catch an error in the willStart call 2`] = `
     if (ctx['state'].error) {
       b2 = text(\`Error handled\`);
     } else {
-      b3 = callSlot(ctx, node, key, 'default', false, {});
+      b3 = callSlot(ctx, node, key, 'default', false, null);
     }
     return block1([], [b2, b3]);
   }
@@ -596,17 +686,18 @@ exports[`can catch errors can catch an error origination from a child's willStar
 "function anonymous(bdom, helpers
 ) {
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { markRaw } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   function slot1(ctx, node, key = \\"\\") {
-    let b3 = component(\`ClassicCompoent\`, {}, key + \`__1\`, node, ctx);
-    let b4 = component(\`ErrorComponent\`, {}, key + \`__2\`, node, ctx);
+    const b3 = component(\`ClassicCompoent\`, {}, key + \`__1\`, node, ctx);
+    const b4 = component(\`ErrorComponent\`, {}, key + \`__2\`, node, ctx);
     return multi([b3, b4]);
   }
   
   return function template(ctx, node, key = \\"\\") {
-    let b5 = component(\`ErrorBoundary\`, {slots: {'default': {__render: slot1, __ctx: ctx}}}, key + \`__3\`, node, ctx);
+    const b5 = component(\`ErrorBoundary\`, {slots: markRaw({'default': {__render: slot1, __ctx: ctx}})}, key + \`__3\`, node, ctx);
     return block1([], [b5]);
   }
 }"
@@ -625,7 +716,7 @@ exports[`can catch errors can catch an error origination from a child's willStar
     if (ctx['state'].error) {
       b2 = text(\`Error handled\`);
     } else {
-      b3 = callSlot(ctx, node, key, 'default', false, {});
+      b3 = callSlot(ctx, node, key, 'default', false, null);
     }
     return block1([], [b2, b3]);
   }
@@ -685,7 +776,7 @@ exports[`can catch errors catchError in catchError 2`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Boom\`, {}, key + \`__1\`, node, ctx);
+    const b2 = component(\`Boom\`, {}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -709,22 +800,22 @@ exports[`can catch errors catching error, rethrow, render parent  -- a main comp
 "function anonymous(bdom, helpers
 ) {
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
-  let { prepareList, capture, withKey } = helpers;
+  let { prepareList, capture, markRaw, withKey } = helpers;
   
   function slot1(ctx, node, key = \\"\\") {
-    let Comp1 = ctx['cp'].Comp;
+    const Comp1 = ctx['cp'].Comp;
     return toggler(Comp1, component(Comp1, {}, key + \`__1\`, node, ctx));
   }
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block1, v_block1, l_block1, c_block1] = prepareList(Object.values(ctx['state'].cps));
+    const [k_block1, v_block1, l_block1, c_block1] = prepareList(Object.values(ctx['state'].cps));;
     for (let i1 = 0; i1 < l_block1; i1++) {
       ctx[\`cp\`] = v_block1[i1];
-      let key1 = ctx['cp'].id;
+      const key1 = ctx['cp'].id;
       const v1 = ctx['cp'];
       const ctx1 = capture(ctx);
-      c_block1[i1] = withKey(component(\`ErrorHandler\`, {onError: ()=>this.cleanUp(v1.id),slots: {'default': {__render: slot1, __ctx: ctx1}}}, key + \`__2__\${key1}\`, node, ctx), key1);
+      c_block1[i1] = withKey(component(\`ErrorHandler\`, {onError: ()=>this.cleanUp(v1.id),slots: markRaw({'default': {__render: slot1, __ctx: ctx1}})}, key + \`__2__\${key1}\`, node, ctx), key1);
     }
     return list(c_block1);
   }
@@ -738,7 +829,7 @@ exports[`can catch errors catching error, rethrow, render parent  -- a main comp
   let { callSlot } = helpers;
   
   return function template(ctx, node, key = \\"\\") {
-    return callSlot(ctx, node, key, 'default', false, {});
+    return callSlot(ctx, node, key, 'default', false, null);
   }
 }"
 `;
@@ -784,22 +875,22 @@ exports[`can catch errors catching in child makes parent render 1`] = `
 "function anonymous(bdom, helpers
 ) {
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
-  let { prepareList, capture, withKey } = helpers;
+  let { prepareList, capture, markRaw, withKey } = helpers;
   
   function slot1(ctx, node, key = \\"\\") {
-    let Comp1 = ctx['elem'][1];
+    const Comp1 = ctx['elem'][1];
     return toggler(Comp1, component(Comp1, {id: ctx['elem'][0]}, key + \`__1\`, node, ctx));
   }
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block1, v_block1, l_block1, c_block1] = prepareList(Object.entries(this.elements));
+    const [k_block1, v_block1, l_block1, c_block1] = prepareList(Object.entries(this.elements));;
     for (let i1 = 0; i1 < l_block1; i1++) {
       ctx[\`elem\`] = v_block1[i1];
-      let key1 = ctx['elem'][0];
+      const key1 = ctx['elem'][0];
       const v1 = ctx['elem'];
       const ctx1 = capture(ctx);
-      c_block1[i1] = withKey(component(\`Catch\`, {onError: (error)=>this.onError(v1[0],error),slots: {'default': {__render: slot1, __ctx: ctx1}}}, key + \`__2__\${key1}\`, node, ctx), key1);
+      c_block1[i1] = withKey(component(\`Catch\`, {onError: (_error)=>this.onError(v1[0],_error),slots: markRaw({'default': {__render: slot1, __ctx: ctx1}})}, key + \`__2__\${key1}\`, node, ctx), key1);
     }
     return list(c_block1);
   }
@@ -813,7 +904,7 @@ exports[`can catch errors catching in child makes parent render 2`] = `
   let { callSlot } = helpers;
   
   return function template(ctx, node, key = \\"\\") {
-    return callSlot(ctx, node, key, 'default', false, {});
+    return callSlot(ctx, node, key, 'default', false, null);
   }
 }"
 `;
@@ -849,6 +940,7 @@ exports[`can catch errors error in mounted on a component with a sibling (proper
 "function anonymous(bdom, helpers
 ) {
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { markRaw } = helpers;
   
   let block1 = createBlock(\`<div><block-child-0/><block-child-1/></div>\`);
   
@@ -857,8 +949,8 @@ exports[`can catch errors error in mounted on a component with a sibling (proper
   }
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`OK\`, {}, key + \`__1\`, node, ctx);
-    let b4 = component(\`ErrorBoundary\`, {slots: {'default': {__render: slot1, __ctx: ctx}}}, key + \`__3\`, node, ctx);
+    const b2 = component(\`OK\`, {}, key + \`__1\`, node, ctx);
+    const b4 = component(\`ErrorBoundary\`, {slots: markRaw({'default': {__render: slot1, __ctx: ctx}})}, key + \`__3\`, node, ctx);
     return block1([], [b2, b4]);
   }
 }"
@@ -888,7 +980,7 @@ exports[`can catch errors error in mounted on a component with a sibling (proper
     if (ctx['state'].error) {
       b2 = text(\`Error handled\`);
     } else {
-      b3 = callSlot(ctx, node, key, 'default', false, {});
+      b3 = callSlot(ctx, node, key, 'default', false, null);
     }
     return block1([], [b2, b3]);
   }
@@ -976,7 +1068,7 @@ exports[`errors and promises a rendering error in a sub component will reject th
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    const b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1018,7 +1110,7 @@ exports[`errors and promises a rendering error will reject the render promise (w
   let block1 = createBlock(\`<div><block-child-0/><block-text-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    const b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
     let txt1 = ctx['x'].y;
     return block1([txt1], [b2]);
   }
@@ -1068,6 +1160,19 @@ exports[`errors and promises an error in mounted call will reject the mount prom
 }"
 `;
 
+exports[`errors and promises an error in onMounted callback will have the component's setup in its stack trace 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block1 = createBlock(\`<div>abc</div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    return block1();
+  }
+}"
+`;
+
 exports[`errors and promises an error in patched call will reject the render promise 1`] = `
 "function anonymous(bdom, helpers
 ) {
@@ -1109,6 +1214,19 @@ exports[`errors and promises errors in mounted and in willUnmount 1`] = `
 }"
 `;
 
+exports[`errors and promises errors in onWillRender/onRender aren't wrapped more than once 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block1 = createBlock(\`<div>abc</div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    return block1();
+  }
+}"
+`;
+
 exports[`errors and promises errors in rerender 1`] = `
 "function anonymous(bdom, helpers
 ) {

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

@@ -37,7 +37,7 @@ exports[`event handling handler receive the event as argument 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     let hdlr1 = [ctx['inc'], ctx];
-    let b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    const b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
     let txt1 = ctx['state'].value;
     return block1([hdlr1, txt1], [b2]);
   }
@@ -99,16 +99,16 @@ exports[`event handling objects from scope are properly captured by t-on 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     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 v1 = ctx['onClick'];
       const v2 = ctx['item'];
-      let hdlr1 = [ev=>v1(v2.val,ev), ctx];
+      let hdlr1 = [_ev=>v1(v2.val,_ev), ctx];
       c_block2[i1] = withKey(block3([hdlr1]), key1);
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     return block1([], [b2]);
   }
 }"
@@ -140,16 +140,16 @@ exports[`event handling t-on with handler bound to dynamic argument on a t-forea
   
   return function template(ctx, node, key = \\"\\") {
     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 v1 = ctx['onClick'];
       const v2 = ctx['item'];
-      let hdlr1 = [ev=>v1(v2,ev), ctx];
+      let hdlr1 = [_ev=>v1(v2,_ev), ctx];
       c_block2[i1] = withKey(block3([hdlr1]), key1);
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     return block1([], [b2]);
   }
 }"

tests/components/__snapshots__/higher_order_component.test.ts.snap

@@ -147,7 +147,7 @@ exports[`basics top level sub widget with a parent 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`ComponentB\`, {}, key + \`__1\`, node, ctx);
+    const b2 = component(\`ComponentB\`, {}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"

tests/components/__snapshots__/hooks.test.ts.snap

@@ -103,20 +103,78 @@ exports[`hooks mounted callbacks should be called in reverse order from willUnmo
 }"
 `;
 
-exports[`hooks parent and child env 1`] = `
+exports[`hooks parent and child env (with useChildSubEnv then useSubEnv) 1`] = `
 "function anonymous(bdom, helpers
 ) {
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = text(ctx['env'].val);
-    let b3 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    const b2 = text(ctx['env'].val);
+    const b3 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
     return multi([b2, b3]);
   }
 }"
 `;
 
-exports[`hooks parent and child env 2`] = `
+exports[`hooks parent and child env (with useChildSubEnv then useSubEnv) 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block2 = createBlock(\`<div><block-text-0/></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let b2;
+    if (ctx['env'].hasParent) {
+      let txt1 = ctx['env'].val;
+      b2 = block2([txt1]);
+    }
+    return multi([b2]);
+  }
+}"
+`;
+
+exports[`hooks parent and child env (with useChildSubEnv) 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = text(ctx['env'].val);
+    const b3 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    return multi([b2, b3]);
+  }
+}"
+`;
+
+exports[`hooks parent and child env (with useChildSubEnv) 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block1 = createBlock(\`<div><block-text-0/></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let txt1 = ctx['env'].val;
+    return block1([txt1]);
+  }
+}"
+`;
+
+exports[`hooks parent and child env (with useSubEnv) 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = text(ctx['env'].val);
+    const b3 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    return multi([b2, b3]);
+  }
+}"
+`;
+
+exports[`hooks parent and child env (with useSubEnv) 2`] = `
 "function anonymous(bdom, helpers
 ) {
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
@@ -144,7 +202,7 @@ exports[`hooks two different call to willPatch/patched should work 1`] = `
 }"
 `;
 
-exports[`hooks use sub env does not pollute user env 1`] = `
+exports[`hooks useChildSubEnv does not pollute user env 1`] = `
 "function anonymous(bdom, helpers
 ) {
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
@@ -158,7 +216,7 @@ exports[`hooks use sub env does not pollute user env 1`] = `
 }"
 `;
 
-exports[`hooks use sub env supports arbitrary descriptor 1`] = `
+exports[`hooks useChildSubEnv supports arbitrary descriptor 1`] = `
 "function anonymous(bdom, helpers
 ) {
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
@@ -169,7 +227,7 @@ exports[`hooks use sub env supports arbitrary descriptor 1`] = `
 }"
 `;
 
-exports[`hooks use sub env supports arbitrary descriptor 2`] = `
+exports[`hooks useChildSubEnv supports arbitrary descriptor 2`] = `
 "function anonymous(bdom, helpers
 ) {
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
@@ -243,6 +301,19 @@ exports[`hooks useEffect hook effect with empty dependency list never reruns 1`]
 }"
 `;
 
+exports[`hooks useEffect hook properly behaves when the effect function throws 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block1 = createBlock(\`<div/>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    return block1();
+  }
+}"
+`;
+
 exports[`hooks useExternalListener 1`] = `
 "function anonymous(bdom, helpers
 ) {
@@ -287,3 +358,43 @@ exports[`hooks useRef hook: basic use 1`] = `
   }
 }"
 `;
+
+exports[`hooks useSubEnv modifies user env 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block1 = createBlock(\`<div><block-text-0/></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let txt1 = ctx['env'].val;
+    return block1([txt1]);
+  }
+}"
+`;
+
+exports[`hooks useSubEnv supports arbitrary descriptor 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return component(\`Child\`, {}, key + \`__1\`, node, ctx);
+  }
+}"
+`;
+
+exports[`hooks useSubEnv supports arbitrary descriptor 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block1 = createBlock(\`<div><block-text-0/> <block-text-1/></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let txt1 = ctx['env'].someVal;
+    let txt2 = ctx['env'].someVal2;
+    return block1([txt1, txt2]);
+  }
+}"
+`;

tests/components/__snapshots__/lifecycle.test.ts.snap

@@ -21,8 +21,8 @@ exports[`lifecycle hooks component semantics 1`] = `
   let block1 = createBlock(\`<div>A<block-child-0/><block-child-1/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`B\`, {}, key + \`__1\`, node, ctx);
-    let b3 = component(\`C\`, {}, key + \`__2\`, node, ctx);
+    const b2 = component(\`B\`, {}, key + \`__1\`, node, ctx);
+    const b3 = component(\`C\`, {}, key + \`__2\`, node, ctx);
     return block1([], [b2, b3]);
   }
 }"
@@ -110,7 +110,7 @@ exports[`lifecycle hooks components are unmounted and destroyed if no longer in
   return function template(ctx, node, key = \\"\\") {
     let b2;
     if (ctx['state'].flag) {
-      let b3 = component(\`Child\`, {n: ctx['state'].n}, key + \`__1\`, node, ctx);
+      const b3 = component(\`Child\`, {n: ctx['state'].n}, key + \`__1\`, node, ctx);
       b2 = block2([], [b3]);
     }
     return multi([b2]);
@@ -160,6 +160,34 @@ exports[`lifecycle hooks components are unmounted destroyed if no longer in DOM
 }"
 `;
 
+exports[`lifecycle hooks destroy new children before being mountged 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    let b2,b3,b4;
+    b2 = text(\`before\`);
+    if (ctx['state'].flag) {
+      b3 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    }
+    b4 = text(\`after\`);
+    return multi([b2, b3, b4]);
+  }
+}"
+`;
+
+exports[`lifecycle hooks destroy new children before being mountged 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return text(\`child\`);
+  }
+}"
+`;
+
 exports[`lifecycle hooks hooks are called in proper order in widget creation/destruction 1`] = `
 "function anonymous(bdom, helpers
 ) {
@@ -168,7 +196,7 @@ exports[`lifecycle hooks hooks are called in proper order in widget creation/des
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    const b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -217,7 +245,7 @@ exports[`lifecycle hooks lifecycle semantics 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, {a: ctx['state'].a}, key + \`__1\`, node, ctx);
+    const b2 = component(\`Child\`, {a: ctx['state'].a}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -430,7 +458,7 @@ exports[`lifecycle hooks mounted hook is called on subcomponents, in proper orde
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    const b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -474,7 +502,7 @@ exports[`lifecycle hooks mounted hook is called on subsubcomponents, in proper o
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`ChildChild\`, {}, key + \`__1\`, node, ctx);
+    const b2 = component(\`ChildChild\`, {}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -499,7 +527,7 @@ exports[`lifecycle hooks onWillRender 1`] = `
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
-    return component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    return component(\`Child\`, {someValue: ctx['state'].value}, key + \`__1\`, node, ctx);
   }
 }"
 `;
@@ -527,7 +555,7 @@ exports[`lifecycle hooks patched hook is called after updateProps 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, {a: ctx['state'].a}, key + \`__1\`, node, ctx);
+    const b2 = component(\`Child\`, {a: ctx['state'].a}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -630,6 +658,43 @@ exports[`lifecycle hooks sub widget (inside sub node): hooks are correctly calle
 }"
 `;
 
+exports[`lifecycle hooks timeout in onWillStart emits a warning 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block1 = createBlock(\`<span/>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    return block1();
+  }
+}"
+`;
+
+exports[`lifecycle hooks timeout in onWillUpdateProps emits a warning 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    const props1 = {prop: ctx['state'].prop};
+    helpers.validateProps(\`Child\`, props1, ctx);
+    return component(\`Child\`, props1, key + \`__1\`, node, ctx);
+  }
+}"
+`;
+
+exports[`lifecycle hooks timeout in onWillUpdateProps emits a warning 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return text(\`\`);
+  }
+}"
+`;
+
 exports[`lifecycle hooks willPatch, patched hook are called on subsubcomponents, in proper order 1`] = `
 "function anonymous(bdom, helpers
 ) {
@@ -638,7 +703,7 @@ exports[`lifecycle hooks willPatch, patched hook are called on subsubcomponents,
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, {n: ctx['state'].n}, key + \`__1\`, node, ctx);
+    const b2 = component(\`Child\`, {n: ctx['state'].n}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -652,7 +717,7 @@ exports[`lifecycle hooks willPatch, patched hook are called on subsubcomponents,
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`ChildChild\`, {n: ctx['props'].n}, key + \`__1\`, node, ctx);
+    const b2 = component(\`ChildChild\`, {n: ctx['props'].n}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"

tests/components/__snapshots__/props.test.ts.snap

@@ -8,7 +8,7 @@ exports[`basics accept ES6-like syntax for props (with getters) 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, {greetings: ctx['greetings']}, key + \`__1\`, node, ctx);
+    const b2 = component(\`Child\`, {greetings: ctx['greetings']}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -36,13 +36,13 @@ exports[`basics arrow functions as prop correctly capture their scope 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['items']);
+    const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['items']);;
     for (let i1 = 0; i1 < l_block1; i1++) {
       ctx[\`item\`] = v_block1[i1];
-      let key1 = ctx['item'].val;
+      const key1 = ctx['item'].val;
       const v1 = ctx['onClick'];
       const v2 = ctx['item'];
-      c_block1[i1] = withKey(component(\`Child\`, {onClick: ev=>v1(v2.val,ev)}, key + \`__1__\${key1}\`, node, ctx), key1);
+      c_block1[i1] = withKey(component(\`Child\`, {onClick: _ev=>v1(v2.val,_ev)}, key + \`__1__\${key1}\`, node, ctx), key1);
     }
     return list(c_block1);
   }
@@ -71,7 +71,7 @@ exports[`basics explicit object prop 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, {value: ctx['state'].val}, key + \`__1\`, node, ctx);
+    const b2 = component(\`Child\`, {value: ctx['state'].val}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -158,7 +158,7 @@ exports[`basics t-set with a body expression can be passed in props, and then t-
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1
     ctx[\`abc\`] = new LazyValue(value1, ctx, node);
-    let b3 = component(\`Child\`, {val: ctx['abc']}, key + \`__1\`, node, ctx);
+    const b3 = component(\`Child\`, {val: ctx['abc']}, key + \`__1\`, node, ctx);
     return block1([], [b3]);
   }
 }"
@@ -174,7 +174,7 @@ exports[`basics t-set with a body expression can be passed in props, and then t-
   
   return function template(ctx, node, key = \\"\\") {
     let txt1 = ctx['props'].val;
-    let b2 = safeOutput(ctx['props'].val);
+    const b2 = safeOutput(ctx['props'].val);
     return block1([txt1], [b2]);
   }
 }"
@@ -192,7 +192,7 @@ exports[`basics t-set with a body expression can be used as textual prop 1`] = `
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1
     setContextValue(ctx, \\"abc\\", \`42\`);
-    let b2 = component(\`Child\`, {val: ctx['abc']}, key + \`__1\`, node, ctx);
+    const b2 = component(\`Child\`, {val: ctx['abc']}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -224,7 +224,7 @@ exports[`basics t-set works  1`] = `
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1
     setContextValue(ctx, \\"val\\", 42);
-    let b2 = component(\`Child\`, {val: ctx['val']}, key + \`__1\`, node, ctx);
+    const b2 = component(\`Child\`, {val: ctx['val']}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -273,7 +273,7 @@ exports[`bound functions is referentially equal after update 1`] = `
   let { bind } = helpers;
   
   return function template(ctx, node, key = \\"\\") {
-    return component(\`Child\`, {val: ctx['state'].val,fn: bind(ctx, ctx['someFunction'])}, key + \`__1\`, node, ctx);
+    return component(\`Child\`, {val: ctx['state'].val, fn: bind(ctx, ctx['someFunction'])}, key + \`__1\`, node, ctx);
   }
 }"
 `;

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

@@ -1,6 +1,19 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
-exports[`default props can set default required boolean values 1`] = `
+exports[`default props a default prop cannot be defined on a mandatory prop 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    const props1 = {};
+    helpers.validateProps(\`Child\`, props1, ctx);
+    return component(\`Child\`, props1, key + \`__1\`, node, ctx);
+  }
+}"
+`;
+
+exports[`default props can set default boolean values 1`] = `
 "function anonymous(bdom, helpers
 ) {
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
@@ -8,15 +21,15 @@ exports[`default props can set default required boolean values 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
 `;
 
-exports[`default props can set default required boolean values 2`] = `
+exports[`default props can set default boolean values 2`] = `
 "function anonymous(bdom, helpers
 ) {
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
@@ -44,9 +57,9 @@ exports[`default props can set default values 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -74,9 +87,9 @@ exports[`default props default values are also set whenever component is updated
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['state'].p}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['state'].p};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -102,8 +115,8 @@ exports[`props validation can specify that additional props are allowed (array)
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {message: 'm',otherProp: 'o'}
-    helpers.validateProps(\`Child\`, props1, ctx)
+    const props1 = {message: 'm', otherProp: 'o'};
+    helpers.validateProps(\`Child\`, props1, ctx);
     return component(\`Child\`, props1, key + \`__1\`, node, ctx);
   }
 }"
@@ -128,8 +141,8 @@ exports[`props validation can specify that additional props are allowed (object)
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {message: 'm',otherProp: 'o'}
-    helpers.validateProps(\`Child\`, props1, ctx)
+    const props1 = {message: 'm', otherProp: 'o'};
+    helpers.validateProps(\`Child\`, props1, ctx);
     return component(\`Child\`, props1, key + \`__1\`, node, ctx);
   }
 }"
@@ -156,9 +169,9 @@ exports[`props validation can validate a prop with multiple types 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -185,9 +198,9 @@ exports[`props validation can validate a prop with multiple types 3`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -214,9 +227,9 @@ exports[`props validation can validate a prop with multiple types 5`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -230,9 +243,9 @@ exports[`props validation can validate an array with given primitive type 1`] =
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -259,9 +272,9 @@ exports[`props validation can validate an array with given primitive type 3`] =
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -288,9 +301,9 @@ exports[`props validation can validate an array with given primitive type 5`] =
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -304,9 +317,9 @@ exports[`props validation can validate an array with given primitive type 6`] =
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -320,9 +333,9 @@ exports[`props validation can validate an array with multiple sub element types
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -349,9 +362,9 @@ exports[`props validation can validate an array with multiple sub element types
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -378,9 +391,9 @@ exports[`props validation can validate an array with multiple sub element types
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -407,9 +420,9 @@ exports[`props validation can validate an array with multiple sub element types
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -423,9 +436,9 @@ exports[`props validation can validate an object with simple shape 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -452,9 +465,9 @@ exports[`props validation can validate an object with simple shape 3`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -468,9 +481,9 @@ exports[`props validation can validate an object with simple shape 4`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -484,9 +497,9 @@ exports[`props validation can validate an object with simple shape 5`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -500,9 +513,9 @@ exports[`props validation can validate an optional props 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -529,9 +542,9 @@ exports[`props validation can validate an optional props 3`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -558,9 +571,9 @@ exports[`props validation can validate an optional props 5`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -574,9 +587,9 @@ exports[`props validation can validate recursively complicated prop def 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -603,9 +616,9 @@ exports[`props validation can validate recursively complicated prop def 3`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -632,9 +645,9 @@ exports[`props validation can validate recursively complicated prop def 5`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -648,9 +661,9 @@ exports[`props validation default values are applied before validating props at
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['state'].p}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['state'].p};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -678,9 +691,9 @@ exports[`props validation missing required boolean prop causes an error 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -694,9 +707,9 @@ exports[`props validation mix of optional and mandatory 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {}
-    helpers.validateProps(\`Child\`, props1, ctx)
-    let b2 = component(\`Child\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {};
+    helpers.validateProps(\`Child\`, props1, ctx);
+    const b2 = component(\`Child\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -710,9 +723,9 @@ exports[`props validation props are validated in dev mode (code snapshot) 1`] =
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {message: 1}
-    helpers.validateProps(\`Child\`, props1, ctx)
-    let b2 = component(\`Child\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {message: 1};
+    helpers.validateProps(\`Child\`, props1, ctx);
+    const b2 = component(\`Child\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -740,9 +753,9 @@ exports[`props validation props are validated whenever component is updated 1`]
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['state'].p}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['state'].p};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -770,9 +783,9 @@ exports[`props validation props: list of strings 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -786,9 +799,9 @@ exports[`props validation validate simple types 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -802,9 +815,9 @@ exports[`props validation validate simple types 2`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -831,9 +844,9 @@ exports[`props validation validate simple types 4`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -847,9 +860,9 @@ exports[`props validation validate simple types 5`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -863,9 +876,9 @@ exports[`props validation validate simple types 6`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -892,9 +905,9 @@ exports[`props validation validate simple types 8`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -908,9 +921,9 @@ exports[`props validation validate simple types 9`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -924,9 +937,9 @@ exports[`props validation validate simple types 10`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -953,9 +966,9 @@ exports[`props validation validate simple types 12`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -969,9 +982,9 @@ exports[`props validation validate simple types 13`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -985,9 +998,9 @@ exports[`props validation validate simple types 14`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1014,9 +1027,9 @@ exports[`props validation validate simple types 16`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1030,9 +1043,9 @@ exports[`props validation validate simple types 17`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1046,9 +1059,9 @@ exports[`props validation validate simple types 18`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1075,9 +1088,9 @@ exports[`props validation validate simple types 20`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1091,9 +1104,9 @@ exports[`props validation validate simple types 21`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1107,9 +1120,9 @@ exports[`props validation validate simple types 22`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1136,9 +1149,9 @@ exports[`props validation validate simple types 24`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1152,9 +1165,9 @@ exports[`props validation validate simple types, alternate form 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1168,9 +1181,9 @@ exports[`props validation validate simple types, alternate form 2`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1197,9 +1210,9 @@ exports[`props validation validate simple types, alternate form 4`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1213,9 +1226,9 @@ exports[`props validation validate simple types, alternate form 5`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1229,9 +1242,9 @@ exports[`props validation validate simple types, alternate form 6`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1258,9 +1271,9 @@ exports[`props validation validate simple types, alternate form 8`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1274,9 +1287,9 @@ exports[`props validation validate simple types, alternate form 9`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1290,9 +1303,9 @@ exports[`props validation validate simple types, alternate form 10`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1319,9 +1332,9 @@ exports[`props validation validate simple types, alternate form 12`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1335,9 +1348,9 @@ exports[`props validation validate simple types, alternate form 13`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1351,9 +1364,9 @@ exports[`props validation validate simple types, alternate form 14`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1380,9 +1393,9 @@ exports[`props validation validate simple types, alternate form 16`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1396,9 +1409,9 @@ exports[`props validation validate simple types, alternate form 17`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1412,9 +1425,9 @@ exports[`props validation validate simple types, alternate form 18`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1441,9 +1454,9 @@ exports[`props validation validate simple types, alternate form 20`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1457,9 +1470,9 @@ exports[`props validation validate simple types, alternate form 21`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1473,9 +1486,9 @@ exports[`props validation validate simple types, alternate form 22`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1502,9 +1515,9 @@ exports[`props validation validate simple types, alternate form 24`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {p: ctx['p']}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {p: ctx['p']};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1518,9 +1531,9 @@ exports[`props validation validation is only done in dev mode 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    const props1 = {}
-    helpers.validateProps(\`SubComp\`, props1, ctx)
-    let b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
+    const props1 = {};
+    helpers.validateProps(\`SubComp\`, props1, ctx);
+    const b2 = component(\`SubComp\`, props1, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -1534,7 +1547,7 @@ exports[`props validation validation is only done in dev mode 2`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`SubComp\`, {}, key + \`__1\`, node, ctx);
+    const b2 = component(\`SubComp\`, {}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"

tests/components/__snapshots__/reactivity.test.ts.snap

@@ -1,5 +1,31 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`reactivity in lifecycle Child component doesn't render when state they depend on changes but their parent is about to unmount them 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    let b2;
+    if (ctx['state'].renderChild) {
+      b2 = component(\`Child\`, {state: ctx['state']}, key + \`__1\`, node, ctx);
+    }
+    return multi([b2]);
+  }
+}"
+`;
+
+exports[`reactivity in lifecycle Child component doesn't render when state they depend on changes but their parent is about to unmount them 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return text(ctx['props'].state.content.a);
+  }
+}"
+`;
+
 exports[`reactivity in lifecycle can use a state hook 1`] = `
 "function anonymous(bdom, helpers
 ) {
@@ -28,6 +54,20 @@ exports[`reactivity in lifecycle can use a state hook 2 1`] = `
 }"
 `;
 
+exports[`reactivity in lifecycle can use a state hook on Map 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block1 = createBlock(\`<div><block-text-0/></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let txt1 = ctx['counter'].get('value');
+    return block1([txt1]);
+  }
+}"
+`;
+
 exports[`reactivity in lifecycle change state while mounting component 1`] = `
 "function anonymous(bdom, helpers
 ) {

tests/components/__snapshots__/refs.test.ts.snap

@@ -38,11 +38,31 @@ exports[`refs can use 2 refs with same name in a t-if/t-else situation 1`] = `
 }"
 `;
 
+exports[`refs refs and recursive templates 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block1 = createBlock(\`<p block-ref=\\"0\\"><block-text-1/><block-child-0/></p>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    const refs = ctx.__owl__.refs;
+    const ref1 = (el) => refs[\`root\`] = el;
+    let b2;
+    let txt1 = ctx['props'].tree.value;
+    if (ctx['props'].tree.child) {
+      b2 = component(\`Test\`, {tree: ctx['props'].tree.child}, key + \`__1\`, node, ctx);
+    }
+    return block1([ref1, txt1], [b2]);
+  }
+}"
+`;
+
 exports[`refs refs are properly bound in slots 1`] = `
 "function anonymous(bdom, helpers
 ) {
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
-  let { capture } = helpers;
+  let { capture, markRaw } = helpers;
   
   let block1 = createBlock(\`<div><span class=\\"counter\\"><block-text-0/></span><block-child-0/></div>\`);
   let block2 = createBlock(\`<button block-handler-0=\\"click\\" block-ref=\\"1\\">do something</button>\`);
@@ -57,7 +77,7 @@ exports[`refs refs are properly bound in slots 1`] = `
   return function template(ctx, node, key = \\"\\") {
     let txt1 = ctx['state'].val;
     const ctx1 = capture(ctx);
-    let b3 = component(\`Dialog\`, {slots: {'footer': {__render: slot1, __ctx: ctx1}}}, key + \`__1\`, node, ctx);
+    const b3 = component(\`Dialog\`, {slots: markRaw({'footer': {__render: slot1, __ctx: ctx1}})}, key + \`__1\`, node, ctx);
     return block1([txt1], [b3]);
   }
 }"
@@ -72,7 +92,7 @@ exports[`refs refs are properly bound in slots 2`] = `
   let block1 = createBlock(\`<span><block-child-0/></span>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = callSlot(ctx, node, key, 'footer', false, {});
+    const b2 = callSlot(ctx, node, key, 'footer', false, null);
     return block1([], [b2]);
   }
 }"
@@ -90,8 +110,8 @@ exports[`refs throws if there are 2 same refs at the same time 1`] = `
   return function template(ctx, node, key = \\"\\") {
     const refs = ctx.__owl__.refs;
     const ref1 = multiRefSetter(refs, \`coucou\`);
-    let b2 = block2([ref1]);
-    let b3 = block3([ref1]);
+    const b2 = block2([ref1]);
+    const b3 = block3([ref1]);
     return multi([b2, b3]);
   }
 }"

tests/components/__snapshots__/rendering.test.ts.snap

@@ -0,0 +1,236 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`force render in case of existing render 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return component(\`B\`, {val: ctx['state'].val}, key + \`__1\`, node, ctx);
+  }
+}"
+`;
+
+exports[`force render in case of existing render 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = component(\`C\`, {}, key + \`__1\`, node, ctx);
+    const b3 = text(ctx['props'].val);
+    return multi([b2, b3]);
+  }
+}"
+`;
+
+exports[`force render in case of existing render 3`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return text(\`C\`);
+  }
+}"
+`;
+
+exports[`rendering semantics can force a render to update sub tree 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = text(ctx['state'].value);
+    const b3 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    return multi([b2, b3]);
+  }
+}"
+`;
+
+exports[`rendering semantics can force a render to update sub tree 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return text(\`child\`);
+  }
+}"
+`;
+
+exports[`rendering semantics can render a parent without rendering child 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = text(ctx['state'].value);
+    const b3 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    return multi([b2, b3]);
+  }
+}"
+`;
+
+exports[`rendering semantics can render a parent without rendering child 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return text(\`child\`);
+  }
+}"
+`;
+
+exports[`rendering semantics props are reactive (nested prop) 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return component(\`Child\`, {a: ctx['state']}, key + \`__1\`, node, ctx);
+  }
+}"
+`;
+
+exports[`rendering semantics props are reactive (nested prop) 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return text(ctx['props'].a.b.c);
+  }
+}"
+`;
+
+exports[`rendering semantics props are reactive 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return component(\`Child\`, {a: ctx['state']}, key + \`__1\`, node, ctx);
+  }
+}"
+`;
+
+exports[`rendering semantics props are reactive 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return text(ctx['props'].a.b);
+  }
+}"
+`;
+
+exports[`rendering semantics render need a boolean = true to be 'deep' 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = text(ctx['state'].value);
+    const b3 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    return multi([b2, b3]);
+  }
+}"
+`;
+
+exports[`rendering semantics render need a boolean = true to be 'deep' 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return text(\`child\`);
+  }
+}"
+`;
+
+exports[`rendering semantics render with deep=true followed by render with deep=false work as expected 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = text(\`parent\`);
+    const b3 = text(ctx['state'].value);
+    const b4 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    return multi([b2, b3, b4]);
+  }
+}"
+`;
+
+exports[`rendering semantics render with deep=true followed by render with deep=false work as expected 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = text(\`child\`);
+    const b3 = text(ctx['env'].getValue());
+    return multi([b2, b3]);
+  }
+}"
+`;
+
+exports[`rendering semantics rendering is atomic (for one subtree) 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = text(ctx['state'].obj.val);
+    const b3 = component(\`B\`, {obj: ctx['state'].obj}, key + \`__1\`, node, ctx);
+    return multi([b2, b3]);
+  }
+}"
+`;
+
+exports[`rendering semantics rendering is atomic (for one subtree) 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return component(\`C\`, {obj: ctx['props'].obj}, key + \`__1\`, node, ctx);
+  }
+}"
+`;
+
+exports[`rendering semantics rendering is atomic (for one subtree) 3`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return text(ctx['props'].obj.val);
+  }
+}"
+`;
+
+exports[`rendering semantics works as expected for dynamic number of props 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return component(\`Child\`, Object.assign({}, ctx['state']), key + \`__1\`, node, ctx);
+  }
+}"
+`;
+
+exports[`rendering semantics works as expected for dynamic number of props 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return text(Object.keys(ctx['props']).length);
+  }
+}"
+`;

tests/components/__snapshots__/style_class.test.ts.snap

@@ -20,9 +20,9 @@ exports[`style and class handling can set class on multi root component 2`] = `
   let block3 = createBlock(\`<span block-attribute-0=\\"class\\">b</span>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = block2();
+    const b2 = block2();
     let attr1 = ctx['props'].class;
-    let b3 = block3([attr1]);
+    const b3 = block3([attr1]);
     return multi([b2, b3]);
   }
 }"
@@ -147,7 +147,7 @@ exports[`style and class handling class on sub component, which is switched to a
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
-    return component(\`Child\`, {class: 'someclass',child: ctx['state'].child}, key + \`__1\`, node, ctx);
+    return component(\`Child\`, {class: 'someclass', child: ctx['state'].child}, key + \`__1\`, node, ctx);
   }
 }"
 `;
@@ -205,7 +205,7 @@ exports[`style and class handling class with extra whitespaces (variation) 1`] =
   let block1 = createBlock(\`<p><block-child-0/></p>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, {class: 'a  b c   d'}, key + \`__1\`, node, ctx);
+    const b2 = component(\`Child\`, {class: 'a  b c   d'}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -310,7 +310,7 @@ exports[`style and class handling empty class attribute is not added on widget r
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, {class: undefined}, key + \`__1\`, node, ctx);
+    const b2 = component(\`Child\`, {class: undefined}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -438,7 +438,7 @@ exports[`style and class handling t-att-class is properly added/removed on widge
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, {class: {b:ctx['state'].b}}, key + \`__1\`, node, ctx);
+    const b2 = component(\`Child\`, {class: {b:ctx['state'].b}}, key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"

tests/components/__snapshots__/t_call.test.ts.snap

@@ -9,7 +9,7 @@ exports[`t-call dynamic t-call 1`] = `
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1;
-    let b1 = text(\` owl \`);
+    const b1 = text(\` owl \`);
     ctx[zero] = b1;
     const template1 = (ctx['current'].template);
     return call(this, template1, ctx, node, key + \`__1\`);
@@ -48,9 +48,9 @@ exports[`t-call dynamic t-call: key is propagated 1`] = `
   let { call } = helpers;
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    const b2 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
     const template1 = (ctx['sub']);
-    let b3 = call(this, template1, ctx, node, key + \`__2\`);
+    const b3 = call(this, template1, ctx, node, key + \`__2\`);
     return multi([b2, b3]);
   }
 }"
@@ -91,7 +91,7 @@ exports[`t-call handlers are properly bound through a dynamic t-call 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     const template1 = ('__template__999');
-    let b2 = call(this, template1, ctx, node, key + \`__1\`);
+    const b2 = call(this, template1, ctx, node, key + \`__1\`);
     let txt1 = ctx['counter'];
     return block1([txt1], [b2]);
   }
@@ -122,7 +122,7 @@ exports[`t-call handlers are properly bound through a t-call 1`] = `
   let block1 = createBlock(\`<div><block-child-0/><block-text-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\`);
     let txt1 = ctx['counter'];
     return block1([txt1], [b2]);
   }
@@ -153,7 +153,7 @@ exports[`t-call handlers with arguments are properly bound through a t-call 1`]
   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]);
   }
 }"
@@ -184,7 +184,7 @@ exports[`t-call parent is set within t-call 1`] = `
   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]);
   }
 }"
@@ -266,7 +266,7 @@ exports[`t-call recursive t-call binding this -- static t-call 1`] = `
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1;
     setContextValue(ctx, \\"level\\", 0);
-    let b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    const b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
     return block1([], [b2]);
   }
 }"
@@ -288,11 +288,11 @@ exports[`t-call recursive t-call binding this -- static t-call 2`] = `
     if (ctx['level']<2) {
       let hdlr1 = [\\"stop\\", ctx['onClicked'].bind(this), ctx];
       let txt1 = ctx['level'];
-      let b3 = block3([hdlr1, txt1]);
+      const b3 = block3([hdlr1, txt1]);
       ctx = Object.create(ctx);
       ctx[isBoundary] = 1;
       setContextValue(ctx, \\"level\\", ctx['level']+1);
-      let b4 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+      const b4 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
       ctx = ctx.__proto__;
       b2 = multi([b3, b4]);
     }
@@ -316,7 +316,7 @@ exports[`t-call sub components in two t-calls 1`] = `
     if (ctx['state'].val===1) {
       b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
     } else {
-      let b4 = callTemplate_2.call(this, ctx, node, key + \`__2\`);
+      const b4 = callTemplate_2.call(this, ctx, node, key + \`__2\`);
       b3 = block3([], [b4]);
     }
     return multi([b2, b3]);
@@ -360,17 +360,17 @@ exports[`t-call t-call in t-foreach and children component 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(['a','b','c']);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(['a','b','c']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`val\`] = v_block2[i1];
       ctx[\`val_first\`] = i1 === 0;
       ctx[\`val_last\`] = i1 === v_block2.length - 1;
       ctx[\`val_index\`] = i1;
       ctx[\`val_value\`] = k_block2[i1];
-      let key1 = ctx['val'];
+      const key1 = ctx['val'];
       c_block2[i1] = withKey(callTemplate_1.call(this, ctx, node, key + \`__1__\${key1}\`), key1);
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     return block1([], [b2]);
   }
 }"

tests/components/__snapshots__/t_call_block.test.ts.snap

@@ -8,7 +8,7 @@ exports[`t-call-block simple t-call-block with static text 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = ctx['myBlock']();
+    const b2 = ctx['myBlock']();
     return block1([], [b2]);
   }
 }"

tests/components/__snapshots__/t_component.test.ts.snap

@@ -8,8 +8,8 @@ exports[`t-component can switch between dynamic components without the need for
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let Comp1 = ctx['constructor'].components[ctx['state'].child];
-    let b2 = toggler(Comp1, component(Comp1, {}, key + \`__1\`, node, ctx));
+    const Comp1 = ctx['constructor'].components[ctx['state'].child];
+    const b2 = toggler(Comp1, component(Comp1, {}, key + \`__1\`, node, ctx));
     return block1([], [b2]);
   }
 }"
@@ -48,7 +48,7 @@ exports[`t-component can use dynamic components (the class) if given (with diffe
   
   return function template(ctx, node, key = \\"\\") {
     const tKey_1 = ctx['state'].child;
-    let Comp1 = ctx['myComponent'];
+    const Comp1 = ctx['myComponent'];
     return toggler(tKey_1, toggler(Comp1, component(Comp1, {}, tKey_1 + key + \`__1\`, node, ctx)));
   }
 }"
@@ -87,7 +87,7 @@ exports[`t-component can use dynamic components (the class) if given 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     const tKey_1 = ctx['state'].child;
-    let Comp1 = ctx['myComponent'];
+    const Comp1 = ctx['myComponent'];
     return toggler(tKey_1, toggler(Comp1, component(Comp1, {}, tKey_1 + key + \`__1\`, node, ctx)));
   }
 }"
@@ -127,8 +127,8 @@ exports[`t-component modifying a sub widget 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let Comp1 = ctx['Counter'];
-    let b2 = toggler(Comp1, component(Comp1, {}, key + \`__1\`, node, ctx));
+    const Comp1 = ctx['Counter'];
+    const b2 = toggler(Comp1, component(Comp1, {}, key + \`__1\`, node, ctx));
     return block1([], [b2]);
   }
 }"
@@ -156,7 +156,7 @@ exports[`t-component switching dynamic component 1`] = `
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
-    let Comp1 = ctx['Child'];
+    const Comp1 = ctx['Child'];
     return toggler(Comp1, component(Comp1, {}, key + \`__1\`, node, ctx));
   }
 }"
@@ -192,7 +192,7 @@ exports[`t-component t-component works in simple case 1`] = `
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
   
   return function template(ctx, node, key = \\"\\") {
-    let Comp1 = ctx['Child'];
+    const Comp1 = ctx['Child'];
     return toggler(Comp1, component(Comp1, {}, key + \`__1\`, node, ctx));
   }
 }"

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

@@ -11,14 +11,14 @@ exports[`list of components components in a node in a t-foreach  1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     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 = 'li_'+ctx['item'];
-      let b4 = component(\`Child\`, {item: ctx['item']}, key + \`__1__\${key1}\`, node, ctx);
+      const key1 = 'li_'+ctx['item'];
+      const b4 = component(\`Child\`, {item: ctx['item']}, key + \`__1__\${key1}\`, node, ctx);
       c_block2[i1] = withKey(block3([], [b4]), key1);
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     return block1([], [b2]);
   }
 }"
@@ -46,15 +46,15 @@ exports[`list of components crash on duplicate key in dev mode 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block1, v_block1, l_block1, c_block1] = prepareList([1,2]);
+    const [k_block1, v_block1, l_block1, c_block1] = prepareList([1,2]);;
     const keys1 = new Set();
     for (let i1 = 0; i1 < l_block1; i1++) {
       ctx[\`item\`] = v_block1[i1];
-      let key1 = 'child';
+      const key1 = 'child';
       if (keys1.has(key1)) { throw new Error(\`Got duplicate key in t-foreach: \${key1}\`)}
       keys1.add(key1);
-      const props1 = {}
-      helpers.validateProps(\`Child\`, props1, ctx)
+      const props1 = {};
+      helpers.validateProps(\`Child\`, props1, ctx);
       c_block1[i1] = withKey(component(\`Child\`, props1, key + \`__1__\${key1}\`, node, ctx), key1);
     }
     return list(c_block1);
@@ -84,14 +84,14 @@ exports[`list of components list of sub components inside other nodes 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].blips);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].blips);;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`blip\`] = v_block2[i1];
-      let key1 = ctx['blip'].id;
-      let b4 = component(\`SubComponent\`, {}, key + \`__1__\${key1}\`, node, ctx);
+      const key1 = ctx['blip'].id;
+      const b4 = component(\`SubComponent\`, {}, key + \`__1__\${key1}\`, node, ctx);
       c_block2[i1] = withKey(block3([], [b4]), key1);
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     return block1([], [b2]);
   }
 }"
@@ -120,23 +120,23 @@ exports[`list of components reconciliation alg works for t-foreach in t-foreach
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].s);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].s);;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`section\`] = v_block2[i1];
       ctx[\`section_index\`] = i1;
-      let key1 = ctx['section_index'];
+      const key1 = ctx['section_index'];
       ctx = Object.create(ctx);
-      const [k_block3, v_block3, l_block3, c_block3] = prepareList(ctx['section'].blips);
+      const [k_block3, v_block3, l_block3, c_block3] = prepareList(ctx['section'].blips);;
       for (let i2 = 0; i2 < l_block3; i2++) {
         ctx[\`blip\`] = v_block3[i2];
         ctx[\`blip_index\`] = i2;
-        let key2 = ctx['blip_index'];
+        const key2 = ctx['blip_index'];
         c_block3[i2] = withKey(component(\`Child\`, {blip: ctx['blip']}, key + \`__1__\${key1}__\${key2}\`, node, ctx), 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]);
   }
 }"
@@ -168,23 +168,23 @@ exports[`list of components reconciliation alg works for t-foreach in t-foreach,
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].rows);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].rows);;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`row\`] = v_block2[i1];
-      let key1 = ctx['row'];
+      const key1 = ctx['row'];
       ctx = Object.create(ctx);
-      const [k_block4, v_block4, l_block4, c_block4] = prepareList(ctx['state'].cols);
+      const [k_block4, v_block4, l_block4, c_block4] = prepareList(ctx['state'].cols);;
       for (let i2 = 0; i2 < l_block4; i2++) {
         ctx[\`col\`] = v_block4[i2];
-        let key2 = ctx['col'];
-        let b6 = component(\`Child\`, {row: ctx['row'],col: ctx['col']}, key + \`__1__\${key1}__\${key2}\`, node, ctx);
+        const key2 = ctx['col'];
+        const b6 = component(\`Child\`, {row: ctx['row'], col: ctx['col']}, key + \`__1__\${key1}__\${key2}\`, node, ctx);
         c_block4[i2] = withKey(block5([], [b6]), key2);
       }
       ctx = ctx.__proto__;
-      let b4 = list(c_block4);
+      const b4 = list(c_block4);
       c_block2[i1] = withKey(block3([], [b4]), key1);
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     return block1([], [b2]);
   }
 }"
@@ -212,10 +212,10 @@ exports[`list of components simple list 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['state'].elems);
+    const [k_block1, v_block1, l_block1, c_block1] = prepareList(ctx['state'].elems);;
     for (let i1 = 0; i1 < l_block1; i1++) {
       ctx[\`elem\`] = v_block1[i1];
-      let key1 = ctx['elem'].id;
+      const key1 = ctx['elem'].id;
       c_block1[i1] = withKey(component(\`Child\`, {value: ctx['elem'].value}, key + \`__1__\${key1}\`, node, ctx), key1);
     }
     return list(c_block1);
@@ -247,13 +247,13 @@ exports[`list of components sub components rendered in a loop 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].numbers);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].numbers);;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`number\`] = v_block2[i1];
-      let key1 = ctx['number'];
+      const key1 = ctx['number'];
       c_block2[i1] = withKey(component(\`Child\`, {n: ctx['number']}, key + \`__1__\${key1}\`, node, ctx), key1);
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     return block1([], [b2]);
   }
 }"
@@ -283,13 +283,13 @@ exports[`list of components sub components with some state rendered in a loop 1`
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].numbers);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].numbers);;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`number\`] = v_block2[i1];
-      let key1 = ctx['number'];
+      const key1 = ctx['number'];
       c_block2[i1] = withKey(component(\`Child\`, {}, key + \`__1__\${key1}\`, node, ctx), key1);
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     return block1([], [b2]);
   }
 }"
@@ -319,13 +319,13 @@ exports[`list of components switch component position 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['clist']);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['clist']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`c\`] = v_block2[i1];
-      let key1 = ctx['c'];
+      const key1 = ctx['c'];
       c_block2[i1] = withKey(component(\`Child\`, {key: ctx['c']}, key + \`__1__\${key1}\`, node, ctx), key1);
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     return block1([], [b2]);
   }
 }"
@@ -355,14 +355,14 @@ exports[`list of components t-foreach with t-component, and update 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(Array(2));
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(Array(2));;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`n\`] = v_block2[i1];
       ctx[\`n_index\`] = i1;
-      let key1 = ctx['n_index'];
+      const key1 = ctx['n_index'];
       c_block2[i1] = withKey(component(\`Child\`, {val: ctx['n_index']}, key + \`__1__\${key1}\`, node, ctx), key1);
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     return block1([], [b2]);
   }
 }"

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

@@ -10,14 +10,14 @@ exports[`t-key t-foreach with t-key switch component position 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['clist']);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['clist']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`c\`] = v_block2[i1];
-      let key1 = ctx['c'];
+      const key1 = ctx['c'];
       const tKey_1 = ctx['key1'];
       c_block2[i1] = withKey(component(\`Child\`, {key: ctx['c']+ctx['key1']}, tKey_1 + key + \`__1__\${key1}\`, node, ctx), tKey_1 + key1);
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     return block1([], [b2]);
   }
 }"
@@ -72,7 +72,7 @@ exports[`t-key t-key on Component as a function 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     const tKey_1 = ctx['key'];
-    let b2 = toggler(tKey_1, component(\`Child\`, {key: ctx['key']}, tKey_1 + key + \`__1\`, node, ctx));
+    const b2 = toggler(tKey_1, component(\`Child\`, {key: ctx['key']}, tKey_1 + key + \`__1\`, node, ctx));
     return block1([], [b2]);
   }
 }"
@@ -101,9 +101,9 @@ exports[`t-key t-key on multiple Components 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     const tKey_1 = ctx['key1'];
-    let b2 = toggler(tKey_1, component(\`Child\`, {key: ctx['key1']}, tKey_1 + key + \`__1\`, node, ctx));
+    const b2 = toggler(tKey_1, component(\`Child\`, {key: ctx['key1']}, tKey_1 + key + \`__1\`, node, ctx));
     const tKey_2 = ctx['key2'];
-    let b3 = toggler(tKey_2, component(\`Child\`, {key: ctx['key2']}, tKey_2 + key + \`__2\`, node, ctx));
+    const b3 = toggler(tKey_2, component(\`Child\`, {key: ctx['key2']}, tKey_2 + key + \`__2\`, node, ctx));
     return block1([], [b2, b3]);
   }
 }"
@@ -139,12 +139,12 @@ exports[`t-key t-key on multiple Components with t-call 1 1`] = `
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1;
     setContextValue(ctx, \\"key\\", ctx['key1']);
-    let b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
+    const b2 = callTemplate_1.call(this, ctx, node, key + \`__1\`);
     ctx = ctx.__proto__;
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1;
     setContextValue(ctx, \\"key\\", ctx['key2']);
-    let b3 = callTemplate_2.call(this, ctx, node, key + \`__2\`);
+    const b3 = callTemplate_2.call(this, ctx, node, key + \`__2\`);
     return block1([], [b2, b3]);
   }
 }"
@@ -186,7 +186,7 @@ exports[`t-key t-key on multiple Components with t-call 2 1`] = `
   let block1 = createBlock(\`<span><block-child-0/></span>\`);
   
   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]);
   }
 }"
@@ -199,9 +199,9 @@ exports[`t-key t-key on multiple Components with t-call 2 2`] = `
   
   return function template(ctx, node, key = \\"\\") {
     const tKey_1 = ctx['key1'];
-    let b2 = toggler(tKey_1, component(\`Child\`, {key: ctx['key1']}, tKey_1 + key + \`__1\`, node, ctx));
+    const b2 = toggler(tKey_1, component(\`Child\`, {key: ctx['key1']}, tKey_1 + key + \`__1\`, node, ctx));
     const tKey_2 = ctx['key2'];
-    let b3 = toggler(tKey_2, component(\`Child\`, {key: ctx['key2']}, tKey_2 + key + \`__2\`, node, ctx));
+    const b3 = toggler(tKey_2, component(\`Child\`, {key: ctx['key2']}, tKey_2 + key + \`__2\`, node, ctx));
     return multi([b2, b3]);
   }
 }"

tests/components/__snapshots__/t_model.test.ts.snap

@@ -10,8 +10,9 @@ exports[`t-model directive .lazy modifier 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     const bExpr1 = ctx['state'];
-    let attr1 = ctx['state']['text'];
-    let hdlr1 = [(ev) => { bExpr1['text'] = ev.target.value; }];
+    const expr1 = 'text';
+    let attr1 = bExpr1[expr1];
+    let hdlr1 = [(ev) => { bExpr1[expr1] = ev.target.value; }];
     let txt1 = ctx['state'].text;
     return block1([attr1, hdlr1, txt1]);
   }
@@ -28,8 +29,9 @@ exports[`t-model directive .number modifier 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     const bExpr1 = ctx['state'];
-    let attr1 = ctx['state']['number'];
-    let hdlr1 = [(ev) => { bExpr1['number'] = toNumber(ev.target.value); }];
+    const expr1 = 'number';
+    let attr1 = bExpr1[expr1];
+    let hdlr1 = [(ev) => { bExpr1[expr1] = toNumber(ev.target.value); }];
     let txt1 = ctx['state'].number;
     return block1([attr1, hdlr1, txt1]);
   }
@@ -46,8 +48,9 @@ exports[`t-model directive .trim modifier 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     const bExpr1 = ctx['state'];
-    let attr1 = ctx['state']['text'];
-    let hdlr1 = [(ev) => { bExpr1['text'] = ev.target.value.trim(); }];
+    const expr1 = 'text';
+    let attr1 = bExpr1[expr1];
+    let hdlr1 = [(ev) => { bExpr1[expr1] = ev.target.value.trim(); }];
     let txt1 = ctx['state'].text;
     return block1([attr1, hdlr1, txt1]);
   }
@@ -64,8 +67,9 @@ exports[`t-model directive basic use, on an input 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     const bExpr1 = ctx['state'];
-    let attr1 = ctx['state']['text'];
-    let hdlr1 = [(ev) => { bExpr1['text'] = ev.target.value; }];
+    const expr1 = 'text';
+    let attr1 = bExpr1[expr1];
+    let hdlr1 = [(ev) => { bExpr1[expr1] = ev.target.value; }];
     let txt1 = ctx['state'].text;
     return block1([attr1, hdlr1, txt1]);
   }
@@ -82,8 +86,9 @@ exports[`t-model directive basic use, on an input with bracket expression 1`] =
   
   return function template(ctx, node, key = \\"\\") {
     const bExpr1 = ctx['state'];
-    let attr1 = ctx['state']['text'];
-    let hdlr1 = [(ev) => { bExpr1['text'] = ev.target.value; }];
+    const expr1 = 'text';
+    let attr1 = bExpr1[expr1];
+    let hdlr1 = [(ev) => { bExpr1[expr1] = ev.target.value; }];
     let txt1 = ctx['state'].text;
     return block1([attr1, hdlr1, txt1]);
   }
@@ -100,8 +105,9 @@ exports[`t-model directive basic use, on another key in component 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     const bExpr1 = ctx['some'];
-    let attr1 = ctx['some']['text'];
-    let hdlr1 = [(ev) => { bExpr1['text'] = ev.target.value; }];
+    const expr1 = 'text';
+    let attr1 = bExpr1[expr1];
+    let hdlr1 = [(ev) => { bExpr1[expr1] = ev.target.value; }];
     let txt1 = ctx['some'].text;
     return block1([attr1, hdlr1, txt1]);
   }
@@ -119,8 +125,9 @@ exports[`t-model directive can also define t-on directive on same event, part 1
   return function template(ctx, node, key = \\"\\") {
     let hdlr1 = [ctx['onInput'], ctx];
     const bExpr1 = ctx['state'];
-    let attr1 = ctx['state']['text'];
-    let hdlr2 = [(ev) => { bExpr1['text'] = ev.target.value; }];
+    const expr1 = 'text';
+    let attr1 = bExpr1[expr1];
+    let hdlr2 = [(ev) => { bExpr1[expr1] = ev.target.value; }];
     return block1([hdlr1, attr1, hdlr2]);
   }
 }"
@@ -137,16 +144,19 @@ exports[`t-model directive can also define t-on directive on same event, part 2
   return function template(ctx, node, key = \\"\\") {
     let hdlr1 = [ctx['onClick'], ctx];
     const bExpr1 = ctx['state'];
-    let attr1 = ctx['state']['choice'] === 'One';
-    let hdlr2 = [(ev) => { bExpr1['choice'] = ev.target.value; }];
+    const expr1 = 'choice';
+    let attr1 = bExpr1[expr1] === 'One';
+    let hdlr2 = [(ev) => { bExpr1[expr1] = ev.target.value; }];
     let hdlr3 = [ctx['onClick'], ctx];
     const bExpr2 = ctx['state'];
-    let attr2 = ctx['state']['choice'] === 'Two';
-    let hdlr4 = [(ev) => { bExpr2['choice'] = ev.target.value; }];
+    const expr2 = 'choice';
+    let attr2 = bExpr2[expr2] === 'Two';
+    let hdlr4 = [(ev) => { bExpr2[expr2] = ev.target.value; }];
     let hdlr5 = [ctx['onClick'], ctx];
     const bExpr3 = ctx['state'];
-    let attr3 = ctx['state']['choice'] === 'Three';
-    let hdlr6 = [(ev) => { bExpr3['choice'] = ev.target.value; }];
+    const expr3 = 'choice';
+    let attr3 = bExpr3[expr3] === 'Three';
+    let hdlr6 = [(ev) => { bExpr3[expr3] = ev.target.value; }];
     return block1([hdlr1, attr1, hdlr2, hdlr3, attr2, hdlr4, hdlr5, attr3, hdlr6]);
   }
 }"
@@ -165,8 +175,9 @@ exports[`t-model directive following a scope protecting directive (e.g. t-set) 1
     ctx[isBoundary] = 1
     setContextValue(ctx, \\"admiral\\", 'Bruno');
     const bExpr1 = ctx['state'];
-    let attr1 = ctx['state']['text'];
-    let hdlr1 = [(ev) => { bExpr1['text'] = ev.target.value; }];
+    const expr1 = 'text';
+    let attr1 = bExpr1[expr1];
+    let hdlr1 = [(ev) => { bExpr1[expr1] = ev.target.value; }];
     return block1([attr1, hdlr1]);
   }
 }"
@@ -183,16 +194,17 @@ exports[`t-model directive in a t-foreach 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state']);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`thing\`] = v_block2[i1];
-      let key1 = ctx['thing'].id;
+      const key1 = ctx['thing'].id;
       const bExpr1 = ctx['thing'];
-      let attr1 = ctx['thing']['f'];
-      let hdlr1 = [(ev) => { bExpr1['f'] = ev.target.checked; }];
+      const expr1 = 'f';
+      let attr1 = bExpr1[expr1];
+      let hdlr1 = [(ev) => { bExpr1[expr1] = ev.target.checked; }];
       c_block2[i1] = withKey(block3([attr1, hdlr1]), key1);
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     return block1([], [b2]);
   }
 }"
@@ -209,17 +221,46 @@ exports[`t-model directive in a t-foreach, part 2 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state']);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`thing\`] = v_block2[i1];
       ctx[\`thing_index\`] = i1;
-      let key1 = ctx['thing_index'];
+      const key1 = ctx['thing_index'];
       const bExpr1 = ctx['state'];
-      let attr1 = ctx['state'][ctx['thing_index']];
-      let hdlr1 = [(ev) => { bExpr1[ctx['thing_index']] = ev.target.value; }];
+      const expr1 = ctx['thing_index'];
+      let attr1 = bExpr1[expr1];
+      let hdlr1 = [(ev) => { bExpr1[expr1] = ev.target.value; }];
       c_block2[i1] = withKey(block3([attr1, hdlr1]), key1);
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
+    return block1([], [b2]);
+  }
+}"
+`;
+
+exports[`t-model directive in a t-foreach, part 3 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { prepareList, toNumber, withKey } = helpers;
+  
+  let block1 = createBlock(\`<div><block-child-0/></div>\`);
+  let block3 = createBlock(\`<input block-attribute-0=\\"value\\" block-handler-1=\\"input\\"/>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    ctx = Object.create(ctx);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['names']);;
+    for (let i1 = 0; i1 < l_block2; i1++) {
+      ctx[\`name\`] = v_block2[i1];
+      ctx[\`name_index\`] = i1;
+      const key1 = ctx['name_index'];
+      const bExpr1 = ctx['state'].values;
+      const expr1 = ctx['name'];
+      let attr1 = bExpr1[expr1];
+      let hdlr1 = [(ev) => { bExpr1[expr1] = ev.target.value; }];
+      c_block2[i1] = withKey(block3([attr1, hdlr1]), key1);
+    }
+    const b2 = list(c_block2);
     return block1([], [b2]);
   }
 }"
@@ -235,8 +276,9 @@ exports[`t-model directive on a select 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     const bExpr1 = ctx['state'];
-    let attr1 = ctx['state']['color'];
-    let hdlr1 = [(ev) => { bExpr1['color'] = ev.target.value; }];
+    const expr1 = 'color';
+    let attr1 = bExpr1[expr1];
+    let hdlr1 = [(ev) => { bExpr1[expr1] = ev.target.value; }];
     let txt1 = ctx['state'].color;
     return block1([attr1, hdlr1, txt1]);
   }
@@ -253,8 +295,9 @@ exports[`t-model directive on a select, initial state 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     const bExpr1 = ctx['state'];
-    let attr1 = ctx['state']['color'];
-    let hdlr1 = [(ev) => { bExpr1['color'] = ev.target.value; }];
+    const expr1 = 'color';
+    let attr1 = bExpr1[expr1];
+    let hdlr1 = [(ev) => { bExpr1[expr1] = ev.target.value; }];
     return block1([attr1, hdlr1]);
   }
 }"
@@ -270,8 +313,9 @@ exports[`t-model directive on a sub state key 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     const bExpr1 = ctx['state'].something;
-    let attr1 = ctx['state'].something['text'];
-    let hdlr1 = [(ev) => { bExpr1['text'] = ev.target.value; }];
+    const expr1 = 'text';
+    let attr1 = bExpr1[expr1];
+    let hdlr1 = [(ev) => { bExpr1[expr1] = ev.target.value; }];
     let txt1 = ctx['state'].something.text;
     return block1([attr1, hdlr1, txt1]);
   }
@@ -288,11 +332,13 @@ exports[`t-model directive on an input type=radio 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     const bExpr1 = ctx['state'];
-    let attr1 = ctx['state']['choice'] === 'One';
-    let hdlr1 = [(ev) => { bExpr1['choice'] = ev.target.value; }];
+    const expr1 = 'choice';
+    let attr1 = bExpr1[expr1] === 'One';
+    let hdlr1 = [(ev) => { bExpr1[expr1] = ev.target.value; }];
     const bExpr2 = ctx['state'];
-    let attr2 = ctx['state']['choice'] === 'Two';
-    let hdlr2 = [(ev) => { bExpr2['choice'] = ev.target.value; }];
+    const expr2 = 'choice';
+    let attr2 = bExpr2[expr2] === 'Two';
+    let hdlr2 = [(ev) => { bExpr2[expr2] = ev.target.value; }];
     let txt1 = ctx['state'].choice;
     return block1([attr1, hdlr1, attr2, hdlr2, txt1]);
   }
@@ -309,11 +355,13 @@ exports[`t-model directive on an input type=radio, with initial value 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     const bExpr1 = ctx['state'];
-    let attr1 = ctx['state']['choice'] === 'One';
-    let hdlr1 = [(ev) => { bExpr1['choice'] = ev.target.value; }];
+    const expr1 = 'choice';
+    let attr1 = bExpr1[expr1] === 'One';
+    let hdlr1 = [(ev) => { bExpr1[expr1] = ev.target.value; }];
     const bExpr2 = ctx['state'];
-    let attr2 = ctx['state']['choice'] === 'Two';
-    let hdlr2 = [(ev) => { bExpr2['choice'] = ev.target.value; }];
+    const expr2 = 'choice';
+    let attr2 = bExpr2[expr2] === 'Two';
+    let hdlr2 = [(ev) => { bExpr2[expr2] = ev.target.value; }];
     return block1([attr1, hdlr1, attr2, hdlr2]);
   }
 }"
@@ -330,8 +378,9 @@ exports[`t-model directive on an input, type=checkbox 1`] = `
   return function template(ctx, node, key = \\"\\") {
     let b2,b3;
     const bExpr1 = ctx['state'];
-    let attr1 = ctx['state']['flag'];
-    let hdlr1 = [(ev) => { bExpr1['flag'] = ev.target.checked; }];
+    const expr1 = 'flag';
+    let attr1 = bExpr1[expr1];
+    let hdlr1 = [(ev) => { bExpr1[expr1] = ev.target.checked; }];
     if (ctx['state'].flag) {
       b2 = text(\`yes\`);
     } else {
@@ -352,14 +401,155 @@ exports[`t-model directive on an textarea 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     const bExpr1 = ctx['state'];
-    let attr1 = ctx['state']['text'];
-    let hdlr1 = [(ev) => { bExpr1['text'] = ev.target.value; }];
+    const expr1 = 'text';
+    let attr1 = bExpr1[expr1];
+    let hdlr1 = [(ev) => { bExpr1[expr1] = ev.target.value; }];
     let txt1 = ctx['state'].text;
     return block1([attr1, hdlr1, txt1]);
   }
 }"
 `;
 
+exports[`t-model directive t-model on an input with an undefined value 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { toNumber } = helpers;
+  
+  let block1 = createBlock(\`<input block-attribute-0=\\"value\\" block-handler-1=\\"input\\"/>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    const bExpr1 = ctx['state'];
+    const expr1 = 'text';
+    let attr1 = bExpr1[expr1];
+    let hdlr1 = [(ev) => { bExpr1[expr1] = ev.target.value; }];
+    return block1([attr1, hdlr1]);
+  }
+}"
+`;
+
+exports[`t-model directive t-model on select with static options 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { toNumber } = helpers;
+  
+  let block1 = createBlock(\`<div><select block-attribute-0=\\"value\\" block-handler-1=\\"change\\"><option value=\\"a\\"><block-text-2/></option><option value=\\"b\\"><block-text-3/></option><option value=\\"c\\"><block-text-4/></option></select></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    const bExpr1 = ctx['state'];
+    const expr1 = 'model';
+    let attr1 = bExpr1[expr1];
+    let hdlr1 = [(ev) => { bExpr1[expr1] = ev.target.value; }];
+    let txt1 = 'a';
+    let txt2 = 'b';
+    let txt3 = 'c';
+    return block1([attr1, hdlr1, txt1, txt2, txt3]);
+  }
+}"
+`;
+
+exports[`t-model directive t-model with dynamic values on select options -- 2 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { toNumber } = helpers;
+  
+  let block1 = createBlock(\`<div><select block-handler-0=\\"change\\"><option block-attribute-1=\\"value\\" block-attribute-2=\\"selected\\"><block-text-3/></option><option block-attribute-4=\\"value\\" block-attribute-5=\\"selected\\"><block-text-6/></option></select></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    const bExpr1 = ctx['state'];
+    const expr1 = 'model';
+    const bValue1 = bExpr1[expr1];
+    let hdlr1 = [(ev) => { bExpr1[expr1] = ev.target.value; }];
+    let attr1 = ctx['options'][0];
+    let attr2 = bValue1 === ctx['options'][0];
+    let txt1 = ctx['options'][0];
+    let attr3 = (ctx['options'][1]);
+    let attr4 = bValue1 === (ctx['options'][1]);
+    let txt2 = ctx['options'][1];
+    return block1([hdlr1, attr1, attr2, txt1, attr3, attr4, txt2]);
+  }
+}"
+`;
+
+exports[`t-model directive t-model with dynamic values on select options -- 3 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { toNumber } = helpers;
+  
+  let block1 = createBlock(\`<div><select block-handler-0=\\"change\\"><option block-attribute-1=\\"value\\" block-attribute-2=\\"selected\\"><block-text-3/></option><option value=\\"b\\" block-attribute-4=\\"selected\\"><block-text-5/></option></select></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    const bExpr1 = ctx['state'];
+    const expr1 = 'model';
+    const bValue1 = bExpr1[expr1];
+    let hdlr1 = [(ev) => { bExpr1[expr1] = ev.target.value; }];
+    let attr1 = ctx['options'][0];
+    let attr2 = bValue1 === ctx['options'][0];
+    let txt1 = ctx['options'][0];
+    let attr3 = bValue1 === \\"b\\";
+    let txt2 = ctx['options'][1];
+    return block1([hdlr1, attr1, attr2, txt1, attr3, txt2]);
+  }
+}"
+`;
+
+exports[`t-model directive t-model with dynamic values on select options 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { toNumber } = helpers;
+  
+  let block1 = createBlock(\`<div><select block-handler-0=\\"change\\"><option block-attribute-1=\\"value\\" block-attribute-2=\\"selected\\"><block-text-3/></option><option block-attribute-4=\\"value\\" block-attribute-5=\\"selected\\"><block-text-6/></option></select></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    const bExpr1 = ctx['state'];
+    const expr1 = 'model';
+    const bValue1 = bExpr1[expr1];
+    let hdlr1 = [(ev) => { bExpr1[expr1] = ev.target.value; }];
+    let attr1 = ctx['options'][0];
+    let attr2 = bValue1 === ctx['options'][0];
+    let txt1 = ctx['options'][0];
+    let attr3 = ctx['options'][1];
+    let attr4 = bValue1 === ctx['options'][1];
+    let txt2 = ctx['options'][1];
+    return block1([hdlr1, attr1, attr2, txt1, attr3, attr4, txt2]);
+  }
+}"
+`;
+
+exports[`t-model directive t-model with dynamic values on select options in foreach 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { toNumber, prepareList, withKey } = helpers;
+  
+  let block1 = createBlock(\`<div><select block-handler-0=\\"change\\"><block-child-0/></select></div>\`);
+  let block3 = createBlock(\`<option block-attribute-0=\\"value\\" block-attribute-1=\\"selected\\"><block-text-2/></option>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    const bExpr1 = ctx['state'];
+    const expr1 = 'model';
+    const bValue1 = bExpr1[expr1];
+    let hdlr1 = [(ev) => { bExpr1[expr1] = ev.target.value; }];
+    ctx = Object.create(ctx);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['options']);;
+    for (let i1 = 0; i1 < l_block2; i1++) {
+      ctx[\`v\`] = v_block2[i1];
+      const key1 = ctx['v'];
+      let attr1 = ctx['v'];
+      let attr2 = bValue1 === ctx['v'];
+      let txt1 = ctx['v'];
+      c_block2[i1] = withKey(block3([attr1, attr2, txt1]), key1);
+    }
+    const b2 = list(c_block2);
+    return block1([hdlr1], [b2]);
+  }
+}"
+`;
+
 exports[`t-model directive two inputs in a div alternating with a t-if 1`] = `
 "function anonymous(bdom, helpers
 ) {
@@ -374,17 +564,38 @@ exports[`t-model directive two inputs in a div alternating with a t-if 1`] = `
     let b2,b3;
     if (ctx['state'].flag) {
       const bExpr1 = ctx['state'];
-      let attr1 = ctx['state']['text1'];
-      let hdlr1 = [(ev) => { bExpr1['text1'] = ev.target.value; }];
+      const expr1 = 'text1';
+      let attr1 = bExpr1[expr1];
+      let hdlr1 = [(ev) => { bExpr1[expr1] = ev.target.value; }];
       b2 = block2([attr1, hdlr1]);
     }
     if (!ctx['state'].flag) {
       const bExpr2 = ctx['state'];
-      let attr2 = ctx['state']['text2'];
-      let hdlr2 = [(ev) => { bExpr2['text2'] = ev.target.value; }];
+      const expr2 = 'text2';
+      let attr2 = bExpr2[expr2];
+      let hdlr2 = [(ev) => { bExpr2[expr2] = ev.target.value; }];
       b3 = block3([attr2, hdlr2]);
     }
     return block1([], [b2, b3]);
   }
 }"
 `;
+
+exports[`t-model directive with expression having a changing key 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { toNumber } = helpers;
+  
+  let block1 = createBlock(\`<div><input block-attribute-0=\\"value\\" block-handler-1=\\"input\\"/><span><block-text-2/></span></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    const bExpr1 = ctx['state'].something;
+    const expr1 = ctx['text'].key;
+    let attr1 = bExpr1[expr1];
+    let hdlr1 = [(ev) => { bExpr1[expr1] = ev.target.value; }];
+    let txt1 = ctx['state'].something[ctx['text'].key];
+    return block1([attr1, hdlr1, txt1]);
+  }
+}"
+`;

tests/components/__snapshots__/t_on.test.ts.snap

@@ -14,17 +14,17 @@ exports[`t-on t-on expression captured 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(ctx['arr']);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['arr']);;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`val\`] = v_block2[i1];
-      let key1 = ctx['val'];
+      const key1 = ctx['val'];
       const v1 = ctx['otherState'];
       const v2 = ctx['iter'];
       let hdlr1 = [()=>v1.vals.push(v2+'_'+v2), ctx];
       setContextValue(ctx, \\"iter\\", ctx['iter']+1);
       c_block2[i1] = withKey(block3([hdlr1]), key1);
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     return block1([], [b2]);
   }
 }"
@@ -41,11 +41,11 @@ exports[`t-on t-on expression in t-foreach 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].values);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].values);;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`val\`] = v_block2[i1];
       ctx[\`val_index\`] = i1;
-      let key1 = ctx['val'];
+      const key1 = ctx['val'];
       let txt1 = ctx['val_index'];
       let txt2 = ctx['val']+'';
       const v1 = ctx['otherState'];
@@ -53,7 +53,7 @@ exports[`t-on t-on expression in t-foreach 1`] = `
       let hdlr1 = [()=>v1.vals.push(v2), ctx];
       c_block2[i1] = withKey(block3([txt1, txt2, hdlr1]), key1);
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     return block1([], [b2]);
   }
 }"
@@ -73,11 +73,11 @@ exports[`t-on t-on expression in t-foreach with t-set 1`] = `
     ctx[isBoundary] = 1
     setContextValue(ctx, \\"bossa\\", 'nova');
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].values);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].values);;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`val\`] = v_block2[i1];
       ctx[\`val_index\`] = i1;
-      let key1 = ctx['val'];
+      const key1 = ctx['val'];
       setContextValue(ctx, \\"bossa\\", ctx['bossa']+'_'+ctx['val_index']);
       let txt1 = ctx['val_index'];
       let txt2 = ctx['val']+'';
@@ -87,7 +87,7 @@ exports[`t-on t-on expression in t-foreach with t-set 1`] = `
       let hdlr1 = [()=>v1.vals.push(v2+'_'+v3), ctx];
       c_block2[i1] = withKey(block3([txt1, txt2, hdlr1]), key1);
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     return block1([], [b2]);
   }
 }"
@@ -104,23 +104,82 @@ exports[`t-on t-on method call in t-foreach 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
-    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].values);
+    const [k_block2, v_block2, l_block2, c_block2] = prepareList(ctx['state'].values);;
     for (let i1 = 0; i1 < l_block2; i1++) {
       ctx[\`val\`] = v_block2[i1];
       ctx[\`val_index\`] = i1;
-      let key1 = ctx['val'];
+      const key1 = ctx['val'];
       let txt1 = ctx['val_index'];
       let txt2 = ctx['val']+'';
       const v1 = ctx['val'];
       let hdlr1 = [()=>this.addVal(v1), ctx];
       c_block2[i1] = withKey(block3([txt1, txt2, hdlr1]), key1);
     }
-    let b2 = list(c_block2);
+    const b2 = list(c_block2);
     return block1([], [b2]);
   }
 }"
 `;
 
+exports[`t-on t-on on components 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { createCatcher } = helpers;
+  const catcher1 = createCatcher({\\"click\\":0});
+  
+  return function template(ctx, node, key = \\"\\") {
+    const hdlr1 = [ctx['increment'], ctx];
+    return catcher1(component(\`Child\`, {value: ctx['state'].value}, key + \`__1\`, node, ctx), [hdlr1]);
+  }
+}"
+`;
+
+exports[`t-on t-on on components 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block1 = createBlock(\`<button><block-text-0/></button>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let txt1 = ctx['props'].value;
+    return block1([txt1]);
+  }
+}"
+`;
+
+exports[`t-on t-on on components, variation 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { createCatcher } = helpers;
+  const catcher1 = createCatcher({\\"click\\":0});
+  
+  let block1 = createBlock(\`<div><span/><block-child-0/><p/></div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    const hdlr1 = [ctx['increment'], ctx];
+    const b2 = catcher1(component(\`Child\`, {value: ctx['state'].value}, key + \`__1\`, node, ctx), [hdlr1]);
+    return block1([], [b2]);
+  }
+}"
+`;
+
+exports[`t-on t-on on components, variation 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block1 = createBlock(\`<button><block-text-0/></button>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let txt1 = ctx['props'].value;
+    return block1([txt1]);
+  }
+}"
+`;
+
 exports[`t-on t-on on destroyed components 1`] = `
 "function anonymous(bdom, helpers
 ) {
@@ -151,3 +210,79 @@ exports[`t-on t-on on destroyed components 2`] = `
   }
 }"
 `;
+
+exports[`t-on t-on on t-set-slots 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { capture, createCatcher, markRaw } = helpers;
+  const catcher1 = createCatcher({\\"click\\":0});
+  
+  let block6 = createBlock(\`<p>something</p>\`);
+  let block7 = createBlock(\`<p>paragraph</p>\`);
+  
+  function slot1(ctx, node, key = \\"\\") {
+    const b6 = block6();
+    const b7 = block7();
+    const hdlr1 = [()=>this.state.count++, ctx];
+    return catcher1(multi([b6, b7]), [hdlr1]);
+  }
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = text(\` [\`);
+    const b3 = text(ctx['state'].count);
+    const b4 = text(\`] \`);
+    const ctx1 = capture(ctx);
+    const b8 = component(\`Child\`, {slots: markRaw({'myslot': {__render: slot1, __ctx: ctx1}})}, key + \`__1\`, node, ctx);
+    return multi([b2, b3, b4, b8]);
+  }
+}"
+`;
+
+exports[`t-on t-on on t-set-slots 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { callSlot } = helpers;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return callSlot(ctx, node, key, 'myslot', false, null);
+  }
+}"
+`;
+
+exports[`t-on t-on on t-slots 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { markRaw } = helpers;
+  
+  let block1 = createBlock(\`<p>something</p>\`);
+  
+  function slot1(ctx, node, key = \\"\\") {
+    return block1();
+  }
+  
+  return function template(ctx, node, key = \\"\\") {
+    return component(\`Child\`, {slots: markRaw({'default': {__render: slot1, __ctx: ctx}})}, key + \`__1\`, node, ctx);
+  }
+}"
+`;
+
+exports[`t-on t-on on t-slots 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  let { callSlot, createCatcher } = helpers;
+  const catcher1 = createCatcher({\\"click\\":0});
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = text(\` [\`);
+    const b3 = text(ctx['state'].count);
+    const b4 = text(\`] \`);
+    const hdlr1 = [()=>this.state.count++, ctx];
+    const b5 = catcher1(callSlot(ctx, node, key, 'default', false, null), [hdlr1]);
+    return multi([b2, b3, b4, b5]);
+  }
+}"
+`;

tests/components/__snapshots__/t_props.test.ts.snap

@@ -8,7 +8,7 @@ exports[`t-props basic use 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, ctx['some'].obj, key + \`__1\`, node, ctx);
+    const b2 = component(\`Child\`, Object.assign({}, ctx['some'].obj), key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -28,6 +28,30 @@ exports[`t-props basic use 2`] = `
 }"
 `;
 
+exports[`t-props child receives a copy of the t-props object, not the original 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return component(\`Child\`, Object.assign({}, ctx['childProps']), key + \`__1\`, node, ctx);
+  }
+}"
+`;
+
+exports[`t-props child receives a copy of the t-props object, not the original 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block1 = createBlock(\`<div/>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    return block1();
+  }
+}"
+`;
+
 exports[`t-props t-props and other props 1`] = `
 "function anonymous(bdom, helpers
 ) {
@@ -36,7 +60,7 @@ exports[`t-props t-props and other props 1`] = `
   let block1 = createBlock(\`<div><div><block-child-0/></div></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Comp\`, Object.assign({}, ctx['state1'], {a: ctx['a']}), key + \`__1\`, node, ctx);
+    const b2 = component(\`Comp\`, Object.assign({}, ctx['state1'], {a: ctx['a']}), key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -65,7 +89,7 @@ exports[`t-props t-props only 1`] = `
   let block1 = createBlock(\`<div><div><block-child-0/></div></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Comp\`, ctx['state'], key + \`__1\`, node, ctx);
+    const b2 = component(\`Comp\`, Object.assign({}, ctx['state']), key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"
@@ -93,7 +117,7 @@ exports[`t-props t-props with props 1`] = `
   let block1 = createBlock(\`<div><block-child-0/></div>\`);
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = component(\`Child\`, Object.assign({}, ctx['childProps'], {a: 1,b: 2}), key + \`__1\`, node, ctx);
+    const b2 = component(\`Child\`, Object.assign({}, ctx['childProps'], {a: 1, b: 2}), key + \`__1\`, node, ctx);
     return block1([], [b2]);
   }
 }"

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

@@ -4,7 +4,7 @@ exports[`t-set slot setted value (with t-set) not accessible with t-esc 1`] = `
 "function anonymous(bdom, helpers
 ) {
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
-  let { isBoundary, withDefault, setContextValue, capture } = helpers;
+  let { isBoundary, withDefault, setContextValue, capture, markRaw } = helpers;
   
   let block1 = createBlock(\`<div><p><block-text-0/></p><block-child-0/><p><block-text-1/></p></div>\`);
   
@@ -21,7 +21,7 @@ exports[`t-set slot setted value (with t-set) not accessible with t-esc 1`] = `
     setContextValue(ctx, \\"iter\\", 'source');
     let txt1 = ctx['iter'];
     const ctx1 = capture(ctx);
-    let b2 = component(\`Childcomp\`, {slots: {'default': {__render: slot1, __ctx: ctx1}}}, key + \`__1\`, node, ctx);
+    const b2 = component(\`Childcomp\`, {slots: markRaw({'default': {__render: slot1, __ctx: ctx1}})}, key + \`__1\`, node, ctx);
     let txt2 = ctx['iter'];
     return block1([txt1, txt2], [b2]);
   }
@@ -51,14 +51,14 @@ exports[`t-set slots with a t-set with a component in body 1`] = `
 "function anonymous(bdom, helpers
 ) {
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
-  let { capture, isBoundary, withDefault, LazyValue, safeOutput } = helpers;
+  let { capture, isBoundary, withDefault, LazyValue, safeOutput, markRaw } = helpers;
   
   function slot1(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1
     ctx[\`v\`] = new LazyValue(value1, ctx, node);
-    let b3 = text(\` in slot \`);
-    let b4 = safeOutput(ctx['v']);
+    const b3 = text(\` in slot \`);
+    const b4 = safeOutput(ctx['v']);
     return multi([b3, b4]);
   }
   
@@ -68,7 +68,7 @@ exports[`t-set slots with a t-set with a component in body 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     const ctx1 = capture(ctx);
-    return component(\`Child\`, {slots: {'default': {__render: slot1, __ctx: ctx1}}}, key + \`__2\`, node, ctx);
+    return component(\`Child\`, {slots: markRaw({'default': {__render: slot1, __ctx: ctx1}})}, key + \`__2\`, node, ctx);
   }
 }"
 `;
@@ -80,8 +80,8 @@ exports[`t-set slots with a t-set with a component in body 2`] = `
   let { callSlot } = helpers;
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = text(\`Child \`);
-    let b3 = callSlot(ctx, node, key, 'default', false, {});
+    const b2 = text(\`Child \`);
+    const b3 = callSlot(ctx, node, key, 'default', false, null);
     return multi([b2, b3]);
   }
 }"
@@ -102,7 +102,7 @@ exports[`t-set slots with an t-set with a component in body 1`] = `
 "function anonymous(bdom, helpers
 ) {
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
-  let { capture, isBoundary, withDefault, LazyValue, safeOutput } = helpers;
+  let { capture, isBoundary, withDefault, LazyValue, safeOutput, markRaw } = helpers;
   
   let block4 = createBlock(\`<div>coffee</div>\`);
   
@@ -110,20 +110,20 @@ exports[`t-set slots with an t-set with a component in body 1`] = `
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1
     ctx[\`v\`] = new LazyValue(value1, ctx, node);
-    let b5 = text(\` tea \`);
-    let b6 = safeOutput(ctx['v']);
+    const b5 = text(\` tea \`);
+    const b6 = safeOutput(ctx['v']);
     return multi([b5, b6]);
   }
   
   function value1(ctx, node, key = \\"\\") {
-    let b3 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
-    let b4 = block4();
+    const b3 = component(\`Child\`, {}, key + \`__1\`, node, ctx);
+    const b4 = block4();
     return multi([b3, b4]);
   }
   
   return function template(ctx, node, key = \\"\\") {
     const ctx1 = capture(ctx);
-    return component(\`Blorg\`, {slots: {'default': {__render: slot1, __ctx: ctx1}}}, key + \`__2\`, node, ctx);
+    return component(\`Blorg\`, {slots: markRaw({'default': {__render: slot1, __ctx: ctx1}})}, key + \`__2\`, node, ctx);
   }
 }"
 `;
@@ -135,8 +135,8 @@ exports[`t-set slots with an t-set with a component in body 2`] = `
   let { callSlot } = helpers;
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = text(\`Blorg \`);
-    let b3 = callSlot(ctx, node, key, 'default', false, {});
+    const b2 = text(\`Blorg \`);
+    const b3 = callSlot(ctx, node, key, 'default', false, null);
     return multi([b2, b3]);
   }
 }"
@@ -157,7 +157,7 @@ exports[`t-set slots with an unused t-set with a component in body 1`] = `
 "function anonymous(bdom, helpers
 ) {
   let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
-  let { capture, isBoundary, withDefault, LazyValue } = helpers;
+  let { capture, isBoundary, withDefault, LazyValue, markRaw } = helpers;
   
   function slot1(ctx, node, key = \\"\\") {
     ctx = Object.create(ctx);
@@ -172,7 +172,7 @@ exports[`t-set slots with an unused t-set with a component in body 1`] = `
   
   return function template(ctx, node, key = \\"\\") {
     const ctx1 = capture(ctx);
-    return component(\`Child\`, {slots: {'default': {__render: slot1, __ctx: ctx1}}}, key + \`__2\`, node, ctx);
+    return component(\`Child\`, {slots: markRaw({'default': {__render: slot1, __ctx: ctx1}})}, key + \`__2\`, node, ctx);
   }
 }"
 `;
@@ -184,8 +184,8 @@ exports[`t-set slots with an unused t-set with a component in body 2`] = `
   let { callSlot } = helpers;
   
   return function template(ctx, node, key = \\"\\") {
-    let b2 = text(\`Child \`);
-    let b3 = callSlot(ctx, node, key, 'default', false, {});
+    const b2 = text(\`Child \`);
+    const b3 = callSlot(ctx, node, key, 'default', false, null);
     return multi([b2, b3]);
   }
 }"
@@ -267,7 +267,7 @@ exports[`t-set t-set not altered by child comp 1`] = `
     ctx[isBoundary] = 1
     setContextValue(ctx, \\"iter\\", 'source');
     let txt1 = ctx['iter'];
-    let b2 = component(\`Childcomp\`, {}, key + \`__1\`, node, ctx);
+    const b2 = component(\`Childcomp\`, {}, key + \`__1\`, node, ctx);
     let txt2 = ctx['iter'];
     return block1([txt1, txt2], [b2]);
   }
@@ -335,7 +335,7 @@ exports[`t-set t-set with a component in body 1`] = `
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1
     ctx[\`v\`] = new LazyValue(value1, ctx, node);
-    let b3 = safeOutput(ctx['v']);
+    const b3 = safeOutput(ctx['v']);
     return block1([], [b3]);
   }
 }"
@@ -369,7 +369,7 @@ exports[`t-set t-set with something in body 1`] = `
     ctx = Object.create(ctx);
     ctx[isBoundary] = 1
     ctx[\`v\`] = new LazyValue(value1, ctx, node);
-    let b3 = safeOutput(ctx['v']);
+    const b3 = safeOutput(ctx['v']);
     return block1([], [b3]);
   }
 }"

tests/components/basics.test.ts

@@ -1,4 +1,4 @@
-import { App, Component, mount, status, useState, xml } from "../../src";
+import { App, Component, mount, status, toRaw, useState, xml } from "../../src";
 import { elem, makeTestFixture, nextTick, snapshotEverything, useLogLifecycle } from "../helpers";
 import { markup } from "../../src/utils";
 
@@ -121,7 +121,7 @@ describe("basics", () => {
     class Test extends Component {
       static template = xml`<span>simple vnode</span>`;
       setup() {
-        expect(this.props).toBe(p);
+        expect(toRaw(this.props)).toBe(p);
       }
     }
 
@@ -171,6 +171,27 @@ describe("basics", () => {
     expect(error!.message).toBe("Cannot mount a component on a detached dom node");
   });
 
+  test("a component cannot be mounted in a detached node (even if node is detached later)", async () => {
+    const warn = console.warn;
+    console.warn = jest.fn();
+    class Test extends Component {
+      static template = xml`<div/>`;
+    }
+    let error: Error;
+    const prom = mount(Test, fixture);
+    await Promise.resolve();
+    fixture.remove();
+    try {
+      await prom;
+    } catch (e) {
+      error = e as Error;
+    }
+    expect(error!).toBeDefined();
+    expect(error!.message).toBe("Cannot mount a component on a detached dom node");
+    expect(console.warn).toBeCalledTimes(1);
+    console.warn = warn;
+  });
+
   test("crashes if it cannot find a template", async () => {
     class Test extends Component {
       static template = "wrongtemplate";
@@ -183,7 +204,7 @@ describe("basics", () => {
       error = e as Error;
     }
     expect(error!).toBeDefined();
-    expect(error!.message).toBe('Missing template: "wrongtemplate"');
+    expect(error!.message).toBe('Missing template: "wrongtemplate" (for component "Test")');
   });
 
   test("class component with dynamic text", async () => {
@@ -1006,4 +1027,31 @@ describe("t-out in components", () => {
       "<div>&lt;b&gt;one&lt;/b&gt;<b>one</b>&lt;b&gt;two&lt;/b&gt;<b>two</b>&lt;b&gt;tree&lt;/b&gt;<b>tree</b></div>"
     );
   });
+
+  test("can switch the contents of two t-out repeatedly", async () => {
+    class Test extends Component {
+      static template = xml`
+        <t t-out="state.a"/>
+        <t t-out="state.b"/>
+      `;
+      state = useState({
+        a: markup("<div>1</div>"),
+        b: markup("<div>2</div>"),
+      });
+
+      reverse() {
+        const { state } = this;
+        [state.a, state.b] = [state.b, state.a];
+      }
+    }
+
+    const comp = await mount(Test, fixture);
+    expect(fixture.innerHTML).toBe("<div>1</div><div>2</div>");
+    comp.reverse();
+    await nextTick();
+    expect(fixture.innerHTML).toBe("<div>2</div><div>1</div>");
+    comp.reverse();
+    await nextTick();
+    expect(fixture.innerHTML).toBe("<div>1</div><div>2</div>");
+  });
 });