SFINAE in practice

sfinae.cpp

#include <iostream>

struct Object
{
    typedef int type;

    static void action()
    {
        std::cout << "Object::action()" << std::endl;
    }
};

template <typename T> 
void f(typename T::type)
{
    std::cout << "f<T>(T::type)" << std::endl;
}

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

template <> 
void f<int>(int)
{
    std::cout << "f<int>(int)" << std::endl;
}

int main()
{
    f(Object());
    f<Object>(10);
    f<int>(10);
}