title: Discover all class implementing an interface
body: <p>Hi I'm using symfony2 framework to make a website. I've defined an interface in PHP like:</p>
  
  <pre><code>interface AdminPluginInterface {
      public function getName();
  }
  </code></pre>
  
  <p>Now I'd like to know all classes, loadable by Symfony2 UniversalClassLoader, that implements my interface, to use them like:</p>
  
  <pre><code>foreach ($classes as $class)
  {
      $class-&gt;getName();
  }
  </code></pre>
  
  <p>Thanks for your answers!</p>