title: passing an argument to add_action
body: <p>Given a function 'plugin_update' that would take a parameter $version, how can I pass a value to this method using the following syntax with the add_action method (as the method is within a class):</p>
  
  <pre><code>add_action('plugins_loaded',array('test-app-class','plugin_update'));
  </code></pre>
  
  <p>I have tried several variations that didn't seem to work. Any advice appreciated!</p>