private function _wrapArgs($caller_args, $num_args=null) {
    $num_args = (is_null($num_args)) ? count($caller_args) - 1 : $num_args;
    
    $filled_args = array();
    if(isset($this) && isset($this->_wrapped)) {
      $filled_args[] =& $this->_wrapped;
    }
    if(count($caller_args) > 0) {
      foreach($caller_args as $k=>$v) {
        $filled_args[] = $v;
      }
    }
    
    return array_pad($filled_args, $num_args, null);
  }