如何轉發聲明以下模板類

Question

我試着轉發declare concurrent_bounded_queue;

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; 
} 

---

我得到以下錯誤：

error C3203: 'cache_aligned_allocator' : unspecialized class template can't be used as a template argument for template parameter 'A', expected a real type 
error C2955: 'tbb::cache_aligned_allocator' : use of class template requires template argument list c:\projects\vitroxreport\src\Executor.h(21) : see declaration of 'tbb::cache_aligned_allocator' 

可我知道我該怎麼避免？

謝謝。

Answer 1

Allocator是一個模板，但隊列的第二個參數是具體類。試試這個：

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; 
};