std::is_final

 

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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.

Template parameters

T

-

a type to check

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

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>

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 (C++11)	checks if a type is a non-union class type (class template)
is_polymorphic (C++11)	checks if a type is polymorphic class type (class template)
std::experimental::is_final_v (library fundamentals TS)	variable template alias of std::is_final::value (variable template)