title: How to get the class from a callable
body: <p>In this situation:</p>
  
  <pre><code>$callable1 = "\somenamespace\someclass::somefunction";
  $callable2 = array('someclass', 'somefunction');
  $callable3 = 'somefunction';
  $callable4 = array($someInstance, 'somefunction');
  </code></pre>
  
  <p>Is there a way I can reliably extract the namespace and class (if any) from a callable, no matter the format in which it is defined?</p>