protected function removeDir(
        /*# string */ $realPath,
        /*# bool */ $keep = false
    )/*# : bool */ {
        if ($keep || @rmdir($realPath)) {
            return true;
        } else {
            return $this->setError(
                Message::get(Message::STR_DELETE_FAIL, $realPath),
                Message::STR_DELETE_FAIL
            );
        }
    }