NAME¶

std::is_final - std::is_final

Synopsis¶

Defined in header <type_traits>
template< class T > (since C++14)
struct is_final;

If T is a final class (that is, a class declared with the final specifier), provides
the member constant value equal true. For any other type, value is false.

If T is a class type, T shall be a complete type; otherwise, the behavior is
undefined.

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

Template parameters¶

T - a type to check

Helper variable template

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

Inherited from std::integral_constant

Member constants¶

value true if T is a final class type , false otherwise
[static] (public static member constant)

Member functions¶

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

Member types¶

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

Notes¶

Final classes cannot be used as base classes.

A union can be marked final (and std::is_final will detect that), even though unions
cannot be used as bases in any case.

Feature-test macro: __cpp_lib_is_final

Example¶

// Run this code

#include <iostream>
#include <type_traits>

class A {};
class B final {};

int main()
{
std::cout
<< std::boolalpha
<< std::is_final<A>::value << '\n'
<< std::is_final<B>::value << '\n';
}

Output:¶

false
true

See also¶

is_class checks if a type is a non-union class type
(C++11) (class template)
is_polymorphic checks if a type is a polymorphic class type
(C++11) (class template)