std::is_final
From cppreference.com
Defined in header <type_traits> | ||
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 |
[edit]Template parameters
T | - | a type to check |
[edit]Helper variable template
template<class T > constexprbool is_final_v = is_final<T>::value; | (since C++17) | |
Inherited from std::integral_constant
Member constants
value [static] | true if T is a final class 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> |
[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.
Feature-test macro | Value | Std | Feature |
---|---|---|---|
__cpp_lib_is_final | 201402L | (C++14) | std::is_final |
[edit]Example
Run this code
#include <type_traits> class A {}; static_assert(std::is_final_v<A>==false); class B final {}; static_assert(std::is_final_v<B>==true); union U final {int x;double d;}; static_assert(std::is_final_v<U>==true); int main(){}
[edit]See also
(C++11) | checks if a type is a non-union class type (class template) |
(C++11) | checks if a type is a polymorphic class type (class template) |