std::is_member_object_pointer

< cpp‎ | types

Defined in header `<type_traits>`
template< class T > struct is_member_object_pointer;		(since C++11)

Checks whether T is a non-static member object pointer. Provides the member constant value which is equal to true, if T is a non-static member object pointer type. Otherwise, value is equal to false.

The behavior of a program that adds specializations for is_member_object_pointer or is_member_object_pointer_v (since C++17) is undefined.

Template parameters

a type to check

Helper variable template

template< class T > inline constexpr bool is_member_object_pointer_v = is_member_object_pointer<T>::value;		(since C++17)

Inherited from std::integral_constant

Member constants

value

[static]

true if T is a pointer to member object , false otherwise
(public static member constant)

Member functions

operator bool	converts the object to bool, returns `value` (public member function)
operator() (C++14)	returns `value` (public member function)

Member types

Type	Definition
`value_type`	`bool`
`type`	std::integral_constant<bool, value>

Possible implementation

template<class T>
struct is_member_object_pointer : std::integral_constant<
                                      bool,
                                      std::is_member_pointer<T>::value &&
                                      !std::is_member_function_pointer<T>::value
                                  > {};

Example

This section is incomplete
Reason: simplify

#include <iostream>
#include <type_traits>
 
int main() {
    class cls {};
    std::cout << (std::is_member_object_pointer<int(cls::*)>::value
                     ? "T is member object pointer"
                     : "T is not a member object pointer") << '\n';
    std::cout << (std::is_member_object_pointer<int(cls::*)()>::value
                     ? "T is member object pointer"
                     : "T is not a member object pointer") << '\n';
}

Output:

T is member object pointer
T is not a member object pointer

is_pointer (C++11)	checks if a type is a pointer type (class template)
is_member_pointer (C++11)	checks if a type is a pointer to an non-static member function or object (class template)
is_member_function_pointer (C++11)	checks if a type is a pointer to a non-static member function (class template)