std::is_destructible, std::is_trivially_destructible, std::is_nothrow_destructible
| 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 Thas a non-deleted destructor, provides the member constantvalueequal true. For any other type,valueis false. | (until C++14) | 
| 1) If  If  If  | (since C++14) | 
2) same as 1), but the destructor does not call any operation that is not trivial.
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.
| Contents | 
[edit] Helper variable templates
| 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) | |
Inherited from std::integral_constant
Member constants
| value [static] | true if Tis destructible, 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> | 
[edit] Notes
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.
[edit] Example
#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
[edit] See also
| (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) | 


