std::has_virtual_destructor

< cpp‎ | types

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

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)

Example

#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