protected function getLoaderClass(
        /*# string */ $suffix,
        /*# string */ $filename
    ) {
        $class = __NAMESPACE__ . '\\Loader' . ucfirst($suffix);
        if (!class_exists($class)) {
            throw new LogicException(
                Message::get(Message::FILE_SUFFIX_UNKNOWN, $filename),
                Message::FILE_SUFFIX_UNKNOWN
            );
        }
        return $class;
    }