c++ - 模板类特化的模板方法

Question

这是我的代码:

template<typename T1, typename T2> class MyClass
{
public:
    template<int num> static int DoSomething();
};

template<typename T1, typename T2> template<int num> int MyClass<T1, T2>::DoSomething()
{
    cout << "This is the common method" << endl;
    cout << "sizeof(T1) = " << sizeof(T1) << endl;
    cout << "sizeof(T2) = " << sizeof(T2) << endl;
    return num;
}

效果很好。但是当我尝试添加这个时

template<typename T1, typename T2> template<> int MyClass<T1, T2>::DoSomething<0>()
{
    cout << "This is ZERO!!!" << endl;
    cout << "sizeof(T1) = " << sizeof(T1) << endl;
    cout << "sizeof(T2) = " << sizeof(T2) << endl;
    return num;
}

我收到编译器错误: «>» 标记前无效的显式特化 «int MyClass::DoSomething()» 的模板 ID «DoSomething<0>» 不匹配任何模板声明

我使用 g++ 4.6.1 我该怎么办？

Answer 1

不幸的是，如果不特化外部模板，就无法特化作为类模板成员的模板:

C++11 14.7.3/16: In an explicit specialization declaration for a member of a class template or a member template that appears in namespace scope, the member template and some of its enclosing class templates may remain unspecialized, except that the declaration shall not explicitly specialize a class member template if its enclosing class templates are not explicitly specialized as well.

我认为您最好的选择是将额外参数添加到 MyClass，然后对其进行部分特化。