template<typename T>
    struct storage_trait {
        static const bool value = false;
    };
    template<>
    struct storage_trait<Storage> {
        static const bool value = true;
    };
    template<>
    struct storage_trait<FileStorage> {
        static const bool value = true;
    };
    template<class T>
    constexpr bool is_storage = storage_trait<T>::value;

    template<class T, bool storage = is_storage<T>>
    class MessageQueue {};

    template<class T>
    class MessageQueue<T, true> {
        // generic implementation
    };

    template<>
    class MessageQueue<FileStorage, is_storage<FileStorage>>: public MessageQueue<T, true> {
        // filestorage implementation
    };