std::is_final (3) - Linux Manuals

std::is_final: std::is_final

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.

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
         (public static member constant)
[static]

Member functions

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

operator() returns value
              (public member function)
(C++14)

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.

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