title: Parent object type hinting in PHP
body: <p>I'm trying to type hint for a specific parent object in PHP:</p>
  
  <p>I've current got a standard base object class:</p>
  
  <pre><code>class stdObject
  {
  
     private $var;
  
     public function setVar($var)
     {
       $this-&gt;var = $var;
       return $this;
     }
  }
  </code></pre>
  
  <p>And I have a class object that extends this:</p>
  
  <pre><code>class valObject extends stdObject
  {
  }
  </code></pre>
  
  <p>In a PHP function, I want to be able to type hint so that the function can expect any object that has a parent of <code>stdObject</code>, so sending in <code>valObject</code> would work but not <code>anyOldObject</code>.</p>
  
  <p>Is this possible?</p>