template_class_subst.cc

#include <type_traits>
#include <iostream>

template<class T, class Enable = void>
struct A {
    static void test() {
        std::cout << "int" << std::endl;
    }
};

template<class T>
struct A<T, typename std::enable_if<std::is_floating_point<T>::value>::type> {
    static void test() {
        std::cout << "float" << std::endl;
    }
};

int main()
{
    A<int>::test();
    A<double>::test();
}