variadic-template-overload.cpp

#include <iostream>
#include <vector>
#include <type_traits>

template < typename Tp, typename... List >
struct contains : std::true_type {};

template < typename Tp, typename Head, typename... Rest >
struct contains<Tp, Head, Rest...>
: std::conditional< std::is_same<Tp, Head>::value,
    std::true_type,
    contains<Tp, Rest...>
>::type {};

template<typename... Types>
struct foo
{
    template<typename Arg, typename = void>
    void f(Arg)
    {
     static_assert(false, "Type is not allowed");
    }
    template<typename Arg, typename std::enable_if<contains<Arg, Types...>::value>::type*>
    void f(Arg)
    {}
};

int main() {
    foo<int, float> f;
    f.f(std::string());
    return 0;
}