std::is_final - cppreference.com (original) (raw)

| | | | | -------------------------------------- | | ------------- | | template< class T > struct is_final; | | (since C++14) |

std::is_final is a UnaryTypeTrait.

If T is a final class, provides the member constant value equal true. For any other type, value is false.

If T is an incomplete class type, the behavior is undefined.

If the program adds specializations for std::is_final or std::is_final_v(since C++17), the behavior is undefined.

Contents

• 1 Template parameters
• 2 Helper variable template
• 3 Inherited from std::integral_constant
  • 3.1 Member constants
  • 3.2 Member functions
  • 3.3 Member types
  • 3.4 Notes
  • 3.5 Example
  • 3.6 See also

[edit] Template parameters

[edit] Helper variable template

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

Inherited from std::integral_constant

Member constants

| | true if T is a final class type, false otherwise (public static member constant) | | ----------------------------------------------------------------------------------- |

Member functions

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

Member types

[edit] Notes

std::is_final is introduced by the resolution of LWG issue 2112.

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

[edit] Example

#include   class A {}; static_assert(std::is_final_v == false);   class B final {}; static_assert(std::is_final_v == true);   union U final { int x; double d; }; static_assert(std::is_final_v == true);   int main() { }

[edit] See also

| | checks if a type is a non-union class type (class template) [edit] | | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | | checks if a type is a polymorphic class type (class template) [edit] |