An interface used to implement caching on a controller

Cacheable.php

<?php
namespace Acme\DemoBundle\Controller;

/**
 * Any controller that implements this interface will be eligible for caching. This works by an event
 * listener that will look to see if the controller implements this interface and if it does, will call its
 * getLastModifiedDate() method to check if the content has been modified or not. If not,
 * then it will tell the controller to simply return the 304 response.
 *
 */
interface Cacheable
{
    /**
     * @return boolean Based on the last modified date determine whether the response has changed or not
     */
    public function isNotModified(\DateTime $lastModified);

    /**
     * Work out the last modified date for our caching strategy
     * @return \DateTime
     */
    public function getLastModifiedDate();
    
    /**
     * @return Response The last modified response
     */
    public function getLastModifiedResponse();
}