method_checker_macro

method_checker.cpp

#define method_checker(name, method, result, ...)\
template <typename T>\
struct name {\
	template <typename testee, result (testee::*)(__VA_ARGS__) = &testee::method> struct tester {};\
	template <typename testee> static std::true_type  test(tester<testee> *);\
	template <typename>        static std::false_type test(...);\
	static constexpr bool has_method = decltype(test<T>(nullptr))::value;\
};

method_checker(has_update, update, void);
method_checker(has_update_i, update, void, int);

struct foo {};
struct bar { void update(); };
struct baz { void update(int); };

int main(int argc, char *argv[]) {
	std::cout << has_update<foo>::has_method << std::endl;
	std::cout << has_update<bar>::has_method << std::endl;
	std::cout << has_update<baz>::has_method << std::endl;
	std::cout << has_update_i<bar>::has_method << std::endl;
	std::cout << has_update_i<baz>::has_method << std::endl;
}