std::is_final (3) - Linux Man Pages

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

See also


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


is_polymorphic checks if a type is a polymorphic class type
               (class template)
(C++11)