check member function
template<typename T> struct has_member_foo11 { private: template<typename U> static auto check(int) -> decltype(std::declval<U>().foo(), std::true_type()); template<typename U> static std::false_type check(...); public: enum { value = std::is_same<decltype(check<T>(0)), std::true_type>::value }; }; //more universal template<typename T, typename... Args> struct has_member_foo11 { private: template<typename U> static auto check(int) -> decltype(std::declval<U>().foo(std::declval<Args>()...), std::true_type()); template<typename U> static std::false_type check(...); public: enum { value = std::is_same<decltype(check<T>(0)), std::true_type>::value }; }; //Improve #define HAS_MEMBER(member)\ template<typename T, typename... Args>struct has_member_##member\ {\ private:\ template<typename U> static auto Check(int) -> decltype(std::declval<U>().member(std::declval<Args>()...), std::true_type());\ template<typename U> static std::false_type Check(...);\ public:\ enum{value = std::is_same<decltype(Check<T>(0)), std::true_type>::value};\ }; //test code HAS_MEMBER(foo) HAS_MEMBER(func) struct MyStruct { string foo() { return ""; } int func(int i) { return i; } }; static_assert(has_member_foo<MyStruct>::value, "true"); static_assert(has_member_func<MyStruct, int>::value, "true");
一点梦想:尽自己一份力,让c++的世界变得更美好!
posted on 2015-11-02 13:58 qicosmos(江南) 阅读(1390) 评论(0) 编辑 收藏 举报