C++ 如何向前声明以下模板类

我尝试前向声明并发有界队列

class MyClass {
    namespace tbb {
        template<typename T> class cache_aligned_allocator;
        template<class T, class A = cache_aligned_allocator> class concurrent_bounded_queue;
    };

    // I wish to maintain this syntax.
    tbb::concurrent_bounded_queue<std::string>& concurrentBoundedQueue;
}

我可以知道如何避免吗

---

谢谢。

分配器是一个模板，但队列的第二个参数是具体类。试试这个：

class MyClass {
    namespace tbb {
        template<typename T> class cache_aligned_allocator;
        template<class T, class A = cache_aligned_allocator<T> > 
            class concurrent_bounded_queue;
    };

    tbb::concurrent_bounded_queue<std::string>& concurrentBoundedQueue;
};

class-MyClass{
名称空间tbb{
模板类缓存\u对齐\u分配器；
样板
类并发有界队列；
};
tbb:：concurrent_bounded_队列和concurrent bounded队列；
};

class MyClass {
    namespace tbb {
        template<typename T> class cache_aligned_allocator;
        template<class T, class A = cache_aligned_allocator<T> > 
            class concurrent_bounded_queue;
    };

    tbb::concurrent_bounded_queue<std::string>& concurrentBoundedQueue;
};