5个以下参数的函数this调用函数

public function showmessage() {   if(!empty($this->showmessage) && is_callable($this->showmessage)) {      $p = func_get_args();      if(is_string($this->showmessage)) {         $fn = $this->showmessage;         switch (func_num_args()) {            case 0:    return $fn();break;            case 1:    return $fn($p[0]);break;            case 2:    return $fn($p[0], $p[1]);break;            case 3:    return $fn($p[0], $p[1], $p[2]);exit;break;            case 4:    return $fn($p[0], $p[1], $p[2], $p[3]);break;            case 5:    return $fn($p[0], $p[1], $p[2], $p[3], $p[4]);break;            default: return call_user_func_array($this->showmessage, $p);break;         }      } else {         return call_user_func_array($this->showmessage, $p);      }   } else {      return func_get_args();   }}