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 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.
Helper variable template
template< class T > 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
See also
(C++11)(C++11)(C++11) | checks if a type has a non-deleted destructor (class template) |
std::experimental::has_virtual_destructor_v
(library fundamentals TS) | variable template alias of std::has_virtual_destructor::value (variable template) |
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