svelte/test/runtime/samples/set-in-observe-dedupes-renders/main.html

<Widget foo='{{foo}}' bar='{{bar}}'/>

<script>
	import Widget from './Widget.html';

	export default {
		data () {
			return {
				foo: { x: 1 },
				bar: { x: 1 }
			}
		},

		oncreate () {
			this.observe( 'foo', foo => {
				this.set({ bar: foo });
			});
		},

		components: {
			Widget
		}
	};
</script>