title: array_diff() failing for no apparent reason
body: <p>i'm trying to diff two arrays and php is returning the following error:</p>
  
  <pre><code>Catchable fatal error: Object of class Node could not be converted to string in D:\projetos\labs\dok\dev\application\models\dok.php on line 410
  </code></pre>
  
  <p>my arrays are, respectively:</p>
  
  <pre><code>array(2)
      object(Node)#5 ...[7 attributes]
      object(Node)#6 ...[7 attributes]
  
  array(1)
      object(Node)#5 ....[7 attributes]
  </code></pre>
  
  <p>I would really appreciate some help here as I have no clue of what's going on. thanks (:</p>
  
  <hr>
  
  <p>as requested, the code around the diff:</p>
  
  <pre><code>// is it a distant child?
  $all_childs = $node-&gt;get_childs(true);
  $distant_childs = array_diff($all_childs, $childs);
  if(in_array($this, $distant_childs))
      return 'distant-child';
  </code></pre>