#include <type_traits>
#include <string>

class A {
public:
	A(const std::wstring&, const std::wstring&)
	{}
	
	template<typename T>
	A(const std::wstring& n, typename std::enable_if<std::is_arithmetic<T>::value, T>::type v)
	{}
};

int main() {
	A(L"n", 1234); // does not compile
	A(L"n", 2.7); // does not compile
	A(L"n", L"n"); // compiles
	return 0;
}