std::has_virtual_destructor

 

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Defined in header <type_traits>
template< class T > struct has_virtual_destructor;		(since C++11)

If T is a type with a virtual destructor, provides the member constant value equal to true. For any other type, value is false.

If T is a non-union class type, T shall be a complete type; otherwise, the behavior is undefined.

The behavior of a program that adds specializations for has_virtual_destructor or has_virtual_destructor_v (since C++17) is undefined.

Template parameters

T

-

a type to check

Helper variable template

template< class T > inline constexpr bool has_virtual_destructor_v = has_virtual_destructor<T>::value;		(since C++17)

Inherited from std::integral_constant

Member constants

value [static]

true if T has a virtual destructor , 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

If a class has a public virtual destructor, it can be derived from, and the derived object can be safely deleted through a pointer to the base object (GotW #18). When true, is_polymorphic is true.

Example

Run this code

#include <iostream>
#include <type_traits>
#include <string>
#include <stdexcept>
 
int main()
{
    std::cout << std::boolalpha
              << "std::string has a virtual destructor? "
              << std::has_virtual_destructor<std::string>::value << '\n'
              << "std::runtime_error has a virtual destructor? "
              << std::has_virtual_destructor<std::runtime_error>::value << '\n';
}

Output:

std::string has a virtual destructor? false
std::runtime_error has a virtual destructor? true

See also

is_destructibleis_trivially_destructibleis_nothrow_destructible (C++11)(C++11)(C++11)	checks if a type has a non-deleted destructor (class template)
is_polymorphic (C++11)	checks if a type is a polymorphic class type (class template)