cpp11chat/check_policy.hpp

24 lines
798 B
C++
Raw Normal View History

#pragma once
#include <type_traits>
#include "chat_messages.hpp"
/* SFINAE compile-type checker for receive policies (as defined in chat_networking.hpp)
* it checks whether PolicyCandidate supplies all of the following methods:
* - void message_do_what(chat_message) */
template <class PolicyCandidate, typename = void>
struct is_valid_policy : std::false_type {};
template <class PolicyCandidate>
struct is_valid_policy<
PolicyCandidate,
typename
std::enable_if<
std::is_same<
decltype(PolicyCandidate
::message_do_what(std::declval<chat::chat_message>())),
void
>::value
>::type>
: std::true_type {};