/**
  * Register a handler function for a template object
  *
  * When parsing a template for display, tags like <roundcube:object name="plugin.myobject" />
  * will be replaced by the return value if the registered callback function.
  *
  * @param string $name Object name (should be unique and start with 'plugin.')
  * @param mixed  $callback Callback function as string or array with object reference and method name
  */
 public function register_handler($name, $callback)
 {
     $this->api->register_handler($name, $this->ID, $callback);
 }