Defined in header <type_traits> | ||
|---|---|---|
template< class T > struct is_destructible; | (1) | (since C++11) |
template< class T > struct is_trivially_destructible; | (2) | (since C++11) |
template< class T > struct is_nothrow_destructible; | (3) | (since C++11) |
1) If an imaginary struct containing a member object of type T has a non-deleted destructor, provides the member constant value equal true. For any other type, value is false. | (until C++14) |
| 1) If If If | (since C++14) |
2) same as 1), and additionally std::remove_all_extents<T>::type is either a non-class type or a class type with a trivial destructor.
3) same as 1), but the destructor is noexcept.
T shall be a complete type, (possibly cv-qualified) void, or an array of unknown bound. Otherwise, the behavior is undefined.
If an instantiation of a template above depends, directly or indirectly, on an incomplete type, and that instantiation could yield a different result if that type were hypothetically completed, the behavior is undefined.
template< class T > inline constexpr bool is_destructible_v = is_destructible<T>::value; | (since C++17) | |
template< class T > inline constexpr bool is_trivially_destructible_v = is_trivially_destructible<T>::value; | (since C++17) | |
template< class T > inline constexpr bool is_nothrow_destructible_v = is_nothrow_destructible<T>::value; | (since C++17) |
| value
[static] | true if T is destructible, false otherwise (public static member constant) |
| operator bool | converts the object to bool, returns value (public member function) |
| operator()
(C++14) | returns value (public member function) |
| Type | Definition |
|---|---|
value_type | bool |
type | std::integral_constant<bool, value> |
Because the C++ program terminates if a destructor throws an exception during stack unwinding (which usually cannot be predicted), all practical destructors are non-throwing even if they are not declared noexcept. All destructors found in the C++ standard library are non-throwing.
Storage occupied by trivially destructible objects may be reused without calling the destructor.
#include <iostream>
#include <string>
#include <type_traits>
struct Foo {
std::string str;
~Foo() noexcept {};
};
struct Bar {
~Bar() = default;
};
int main() {
std::cout << std::boolalpha
<< "std::string is destructible? "
<< std::is_destructible<std::string>::value << '\n'
<< "Foo is nothrow destructible? "
<< std::is_nothrow_destructible<Foo>::value << '\n'
<< "Bar is trivally destructible? "
<< std::is_trivially_destructible<Bar>::value << '\n';
}Output:
std::string is destructible? true Foo is nothrow destructible? true Bar is trivally destructible? true
|
(C++11)(C++11)(C++11) | checks if a type has a constructor for specific arguments (class template) |
|
(C++11) | checks if a type has a virtual destructor (class template) |
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