| Defined in header <type_traits> | ||||
|---|---|---|---|---|
| (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
| (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
1 2 3 4 5 6 7 8 9 10 11 12 13 | #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:
1 2 | std::string has a virtual destructor? falsestd::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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