title: Return an empty but tell php it means `return false`
body: <p>Is it possible to return an array, but also tell php it's supposed to mean false?</p>
  
  <p>Example:</p>
  
  <pre><code>if ($res = a_function()) {
      // all good
  }
  else {
      echo getErrorByNumber($res['err_no']);
  }
  </code></pre>
  
  <p><code>a_function</code>:</p>
  
  <pre><code>function a_function() {
      // do fancy stuff
      if (xy) return true;
      return array('err_no' =&gt; 1);
  }
  </code></pre>
  
  <p>I guess its not possible, since php will always take an array for <code>return true</code>, right?</p>