title: Laravel passing array by reference to an event subscriber
body: <p>Is it possible to pass an array by reference into an event subscriber?</p>
  
  <p>I have an event "user.create.show" and I want to pass an array to the event so I could modify it if needed.</p>
  
  <p>The call looks like this.</p>
  
  <pre><code>Event::fire('user.create.show', array($data));
  </code></pre>
  
  <p>The event subscriber looks like this.</p>
  
  <pre><code>public function createShow(&amp;$data) 
  {
      $data['foo'] = 'bar';
      return $data;
  }
  </code></pre>
  
  <p>I get a "Parameter 1 to UserSubscriber::createShow() expected to be a reference, value given" PHP error.</p>
  
  <p>The line causing the error is the following:</p>
  
  <pre><code>return call_user_func_array($callable, $data);
  </code></pre>
  
  <p>I know I could return it the value, but Laravel returns an array with the variables and an multidimensional array if multiple variables were passed into the event. I could parse the return value but it would make my code a lot cleaner and easier if I could just pass by reference.</p>