work on composability

demo/src/Counter.ts

@@ -15,9 +15,9 @@ export default class Counter extends Widget {
     counter: 0
   };
 
-  constructor(parent: Widget | null, initialState?: number) {
+  constructor(parent: Widget, props: {initialState?: number}) {
     super(parent);
-    this.state.counter = initialState || 0;
+    this.state.counter = props.initialState || 0;
   }
 
   increment(delta: number) {

demo/src/RootWidget.ts

@@ -0,0 +1,29 @@
+import Widget from "../../src/core/widget";
+import Counter from "./Counter";
+
+const template = `
+    <div t-debug="1">
+        <span>Root Widget</span>
+        <button t-on-click="resetCounter">Reset</button>
+        <button t-on-click="toggle">Toggle  Counter</button>
+        <input/>
+        <t t-if="state.validcounter">
+            <t t-widget="Counter" t-ref="counter" t-props="{initialState:4}"/>
+        </t>
+    </div>
+`;
+
+export default class RootWidget extends Widget {
+  name = "root";
+  template = template;
+  widgets = { Counter };
+  state = { validcounter: true};
+
+  resetCounter(ev: MouseEvent) {
+      this.refs.counter.updateState({counter: 3})
+  }
+
+  toggle() {
+      this.updateState({validcounter: !this.state.validcounter});
+  }
+}

demo/src/main.ts

@@ -1,11 +1,10 @@
 ///<amd-module name="main" />
 
-// import RootWidget from "./RootWidget";
-import Counter from "./Counter";
+import RootWidget from "./RootWidget";
 import env from "./env";
 
 document.addEventListener("DOMContentLoaded", async function() {
-  const rootWidget = new Counter(null);
+  const rootWidget = new RootWidget(null);
   rootWidget.setEnvironment(env);
   const mainDiv = document.getElementById("app")!;
   await rootWidget.mount(mainDiv);

src/core/qweb_directives.ts

@@ -218,6 +218,25 @@ const onDirective: Directive = {
   }
 };
 
+const widgetDirective: Directive = {
+  name: "widget",
+  priority: 100,
+  atNodeEncounter({ ctx, fullName, value, node, qweb}): boolean {
+    let spanID = ctx.generateID();
+    ctx.addLine(`let ${spanID} = document.createElement('span')`);
+    ctx.addNode(spanID)
+    let props = node.getAttribute('t-props');
+    let widgetID = ctx.generateID();
+    ctx.addLine(`let ${widgetID} = new context.widgets['${value}'](context, ${props})`);
+    ctx.addLine(`${widgetID}.mount(${spanID}).then(()=>${ctx.parentNode}.replaceChild(${widgetID}.el, ${spanID}))`);
+    let ref = node.getAttribute('t-ref');
+    if (ref) {
+      ctx.addLine(`context.refs['${ref}'] = ${widgetID}`);
+    }
+    return true;
+  }
+};
+
 export default [
   forEachDirective,
   ifDirective,
@@ -227,5 +246,6 @@ export default [
   setDirective,
   escDirective,
   rawDirective,
-  onDirective
+  onDirective,
+  widgetDirective
 ];

src/core/widget.ts

@@ -44,6 +44,8 @@ export default class Widget {
 
   async mount(target: HTMLElement) {
     await this.willStart();
+    this.env!.qweb.addTemplate(this.name, this.template);
+    delete this.template;
     await this.render();
     target.appendChild(this.el!);
   }
@@ -56,8 +58,6 @@ export default class Widget {
 
   setEnvironment(env: Env) {
     this.env = Object.create(env);
-    env.qweb.addTemplate(this.name, this.template);
-    delete this.template;
   }
 
   async updateState(newState: Object) {