demo "partial" specialization of a class template with a member function template

gistfile1.cpp

#include <typeinfo>
#include <string>

#include <iostream>
template<typename T> struct A {
    template<typename U>
    void foo(U u) {
    std::cout << std::string("class template parameter generic, function template parameter ") + typeid(u).name() << std::endl;
    }
};

// Now a special version of foo() for class B only
struct B {};
struct C {};

template<>
template <typename T>
void A<B>::foo(T t) {
    std::cout << std::string("class template parameter B, function template parameter ") + typeid(t).name() << std::endl;
}


struct X {};
struct Y {};

int main() {
    A<C> ac;
    A<B> ab;
    
    X x;
    Y y;

    ac.foo(x);
    ac.foo(y);

    ab.foo(x);
    ab.foo(y);
}