std::is_member_object_pointer

< cpp‎ | types

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

std::is_member_object_pointer is an UnaryTypeTrait.

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 std::is_member_object_pointer or std::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

#include <iostream>
#include <type_traits>
 
int main()
{
    class C {};
    std::cout << "Is member object pointer?\n" << std::boolalpha
              << std::is_member_object_pointer_v<int(C::*)>
              << ": int(C::*)\n"
              << std::is_member_object_pointer_v<int(C::*)()>
              << ": int(C::*)()\n";
}

Output:

Is member object pointer?
true: int(C::*)
false: int(C::*)()

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 a 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)