Subclassing Response for Twig

TwigResponse.php

<?php
namespace GMO\Common\Web\Twig;

use GMO\Common\Collections\ArrayCollection;
use Symfony\Component\HttpFoundation\Response;

class TwigResponse extends Response {

	public function setTemplate($template) {
		$this->template = $template;
		return $this;
	}

	public function getTemplate() {
		return $this->template;
	}

	public function getVariables() {
		return $this->variables;
	}

	public function setVariables($variables) {
		$this->variables = new ArrayCollection($variables);
		return $this;
	}

	/**
	 * @param string $name
	 * @param mixed  $value
	 * @return $this
	 */
	public function addVariable($name, $value) {
		$this->variables->set($name, $value);
		return $this;
	}

	/**
	 * @param ArrayCollection|array $values
	 * @return $this
	 */
	public function addVariables($values) {
		$this->variables->replace($values);
		return $this;
	}

	/**
	 * Constructor.
	 *
	 * @param string $template  The name of the template
	 * @param ArrayCollection|array  $variables The variables for the template
	 * @param int    $status    The response status code
	 * @param array  $headers   An array of response headers
	 *
	 * @throws \InvalidArgumentException When the HTTP status code is not valid
	 *
	 * @api
	 */
	public function __construct($template, $variables = array(), $status = 200, $headers = array()) {
		$this->template = $template;
		$this->variables = new ArrayCollection($variables);
		parent::__construct('', $status, $headers);
	}

	protected $template;
	/** @var ArrayCollection */
	protected $variables;
}

TwigResponseServiceProvider.php

<?php
namespace GMO\Common\Web\Twig;

use Silex\Application;
use Silex\ServiceProviderInterface;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpKernel\Event\FilterResponseEvent;
use Symfony\Component\HttpKernel\KernelEvents;

class TwigResponseServiceProvider implements ServiceProviderInterface, EventSubscriberInterface {

	public function onResponse(FilterResponseEvent $event) {
		$response = $event->getResponse();
		if (!$response instanceof TwigResponse) {
			return;
		}
		
		/** @var \Twig_Environment $twig */
		$twig = $this->app['twig'];
		$content = $twig->render($response->getTemplate(), $response->getVariables()->toArray());
		
		/*
		 * Since content has been rendered it isn't a TwigResponse anymore.
		 * This prevents instanceof TwigResponse checks.
		 */
		$newResponse = new Response($content, $response->getStatusCode());
		$newResponse->headers = $response->headers;
		
		$event->setResponse($newResponse);
	}

	public function register(Application $app) {
		$this->app = $app;
	}

	public function boot(Application $app) {
		$app['dispatcher']->addSubscriber($this);
	}

	/** @inheritdoc */
	public static function getSubscribedEvents() {
		return array(
			KernelEvents::RESPONSE => array('onResponse', -100),
		);
	}

	/** @var Application */
	protected $app;
}