- Use ComponentDidMount and context to attach to container
- On every render, all attached components evaluate their own validation state, and call setState on the corresponding Form property

<Form>
	<ArbitraryComponent/>
	<Input>
</Form>

Const ArbitraryComponent = component(() => <div><Input /></div>);

class Input extends ReactComponent {
	componentDidMount () {
		const meRef = Symbol();
		this.context.validationState[meRef] = { valid: true, messages: [] };
	}

	componentWillReceiveProps (nextProps) {
		const validationResult = this.validate(nextProps);
		if (this.context.validationState[meRef] !== validationResult) {
			this.context.update(validationResult, meRef);
		}
	}
}