title: Is it possible to use SFINAE/templates to check if an operator exists?
body: <p>I'm trying to check if an operator exists at compile time, if it doesn't I just want it ignored, is there any way to do that?</p>
  
  <p>example operator:</p>
  
  <pre><code> template &lt;typename T&gt;
   QDataStream&amp; operator&lt;&lt;(QDataStream&amp; s, const QList&lt;T&gt;&amp; l);
  </code></pre>