Defined in header <type_traits> | ||
---|---|---|
template< class T > struct is_final; | (since C++14) |
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.
T | - | a type to check |
template< class T > inline constexpr bool is_final_v = is_final<T>::value; | (since C++17) |
value
[static] | true if T is a final class type , false otherwise (public static member constant) |
operator bool | converts the object to bool , returns value (public member function) |
operator()
(C++14) | returns value (public member function) |
Type | Definition |
---|---|
value_type | bool |
type | std::integral_constant<bool, value> |
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.
#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
(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) |
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