partial template member specialization

Question

Given the following definitions:

template <typename T>
class A {

public:

   void f();

};

template <typename T>
void
A<T>::f()
{}

template <typename T>
class B {};

How would I partially specialize A<B<T>>::f, i.e. f for some B<T>? I'm basically looking for the right magic to substitute the ??? below

template <???>
void
A<B<T>>::f()
{}

Answer 1

You can have an explicit specialization, from [temp.expl.spec]:

An explicit specialization of any of the following:
— ...
— member function of a class template
— ...
can be declared by a declaration introduced by template<>

That is:

template <>
void A<B<int>>::f() {
    std::cout << "B\n";
}

But you cannot have a partial specialization of a member function of a class template. You would have to partially specialize the entire class:

template <typename T>
class A<B<T>> {
public:
    void f() {
        std::cout << "B\n";
    }

    // ... all other members you want in A<B<T>> ...
};