std::is_member_function_pointer

< cpp‎ | types

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

std::is_member_function_pointer is an UnaryTypeTrait.

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

The behavior of a program that adds specializations for std::is_member_function_pointer or std::is_member_function_pointer_v (since C++17) is undefined.

Template parameters

a type to check

Helper variable template

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

Inherited from std::integral_constant

Member constants

value

[static]

true if T is a member function pointer type, 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_function_pointer_helper : std::false_type {};
 
template<class T, class U>
struct is_member_function_pointer_helper<T U::*> : std::is_function<T> {};
 
template<class T>
struct is_member_function_pointer 
    : is_member_function_pointer_helper<typename std::remove_cv<T>::type> {};

Example

#include <type_traits>
 
class A
{
public:
    void member() {}
};
 
int main()
{
    // fails at compile time if A::member is a data member and not a function
    static_assert(std::is_member_function_pointer<decltype(&A::member)>::value,
                  "A::member is not a member function."); 
}

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