better solution for preventing blowback with inter-component bindings, also fixes #19

compiler/generate/index.js

@@ -260,13 +260,9 @@ export default function generate ( parsed, source, options ) {
 	}
 
 	setStatements.push( deindent`
-		if ( setting ) return;
-
-		setting = true;
 		dispatchObservers( observers.immediate, newState, oldState );
 		if ( mainFragment ) mainFragment.update( newState, state );
 		dispatchObservers( observers.deferred, newState, oldState );
-		setting = false;
 	` );
 
 	const topLevelStatements = [];

compiler/generate/visitors/attributes/binding/index.js

@@ -74,18 +74,24 @@ export default function createBinding ( generator, node, attribute, current, loc
 	}
 
 	if ( local.isComponent ) {
+		generator.hasComplexBindings = true;
+
 		local.init.push( deindent`
 			var ${local.name}_updating = false;
 
-			${local.name}.observe( '${attribute.name}', function ( value ) {
-				${local.name}_updating = true;
-				${setter}
-				${local.name}_updating = false;
+			component.__bindings.push( function () {
+				${local.name}.observe( '${attribute.name}', function ( value ) {
+					${local.name}_updating = true;
+					${setter}
+					${local.name}_updating = false;
+				});
 			});
 		` );
 
 		local.update.push( deindent`
-			if ( !${local.name}_updating ) ${local.name}.set({ ${attribute.name}: ${contextual ? attribute.value : `root.${attribute.value}`} });
+			if ( !${local.name}_updating && '${parts[0]}' in changed ) {
+				${local.name}.set({ ${attribute.name}: ${contextual ? attribute.value : `root.${attribute.value}`} });
+			}
 		` );
 	} else {
 		local.init.push( deindent`

test/compiler/component-binding-parent-supercedes-child/Counter.html

@@ -0,0 +1,9 @@
+<button on:click='set({ count: count + 1 })'>+1</button>
+
+<script>
+	export default {
+		data: () => ({
+			count: 0
+		})
+	};
+</script>

test/compiler/component-binding-parent-supercedes-child/_config.js

@@ -0,0 +1,27 @@
+export default {
+	html: `
+		<button>+1</button>
+		<p>count: 10</p>
+	`,
+
+	test ( assert, component, target, window ) {
+		const click = new window.MouseEvent( 'click' );
+		const button = target.querySelector( 'button' );
+
+		button.dispatchEvent( click );
+
+		assert.equal( component.get( 'x' ), 11 );
+		assert.htmlEqual( target.innerHTML, `
+			<button>+1</button>
+			<p>count: 11</p>
+		` );
+
+		button.dispatchEvent( click );
+
+		assert.equal( component.get( 'x' ), 12 );
+		assert.htmlEqual( target.innerHTML, `
+			<button>+1</button>
+			<p>count: 12</p>
+		` );
+	}
+};

test/compiler/component-binding-parent-supercedes-child/main.html

@@ -0,0 +1,16 @@
+<Counter bind:count='x'/>
+<p>count: {{x}}</p>
+
+<script>
+	import Counter from './Counter.html';
+
+	export default {
+		data: () => ({
+			x: 10
+		}),
+
+		components: {
+			Counter
+		}
+	};
+</script>