std::is_move_constructible, std::is_trivially_move_constructible, std::is_nothrow_move_constructible
De cppreference.com
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<tbody> </tbody>| Definido no cabeçalho <type_traits>
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template< class T > struct is_move_constructible; |
(1) | (desde C++11) |
template< class T > struct is_trivially_move_constructible; |
(2) | (desde C++11) |
template< class T > struct is_nothrow_move_constructible; |
(3) | (desde C++11) |
1)
Verifica se um tipo é
MoveConstructible, ou seja, tem um construtor movimento acessível explícita ou implícita. Se a exigência for atendida, um membro constante value true igual é fornecida, caso contrário, é value false.Original:
Checks whether a type is
MoveConstructible, i.e. has an accessible explicit or implicit move constructor. If the requirement is met, a member constant value equal true is provided, otherwise value is false.The text has been machine-translated via Google Translate.
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2)
Mesmo que 1), mas a expressão construtor movimento não põe qualquer operação que não é trivial.
Original:
Same as 1), but the move constructor expression does not call any operation that is not trivial.
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3)
Mesmo que 1), mas a expressão construtor movimento é noexcept.
Original:
Same as 1), but the move constructor expression is noexcept.
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Herdado de std::integral_constant
Member constants
value [estática] |
true se T is move-constructible , false contrário Original: true if T is move-constructible , false otherwise The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (membro estático público constante) |
Member functions
operator bool |
converte o objeto em bool, retorna value Original: converts the object to bool, returns value The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (função pública membro) |
Member types
Tipo
Original: Type The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
Definition |
value_type
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bool
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type
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std::integral_constant<bool, value>
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Notas
Mover construtores são geralmente noexcept, pois caso contrário, eles não são utilizáveis em qualquer código que fornece garantia exceção forte.
Original:
Move constructors are usually noexcept, since otherwise they are unusable in any code that provides strong exception guarantee.
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Possível implementação
template<class T>
struct is_move_constructible :
std::is_constructible<T, typename std::add_rvalue_reference<T>::type> {};
template<class T>
struct is_trivially_move_constructible :
std::is_trivially_constructible<T, typename std::add_rvalue_reference<T>::type> {};
template<class T>
struct is_nothrow_move_constructible :
std::is_nothrow_constructible<T, typename std::add_rvalue_reference<T>::type> {};
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Exemplo
#include <iostream>
#include <type_traits>
struct Ex1 {
std::string str; // member has a non-trivial but non-throwing move ctor
};
struct Ex2 {
int n;
Ex2(Ex2&&) = default; // trivial and non-throwing
};
int main() {
std::cout << std::boolalpha << "Ex1 is move-constructible? "
<< std::is_move_constructible<Ex1>::value << '\n'
<< "Ex1 is trivially move-constructible? "
<< std::is_trivially_move_constructible<Ex1>::value << '\n'
<< "Ex1 is nothrow move-constructible? "
<< std::is_nothrow_move_constructible<Ex1>::value << '\n'
<< "Ex2 is trivially move-constructible? "
<< std::is_trivially_move_constructible<Ex2>::value << '\n'
<< "Ex2 is nothrow move-constructible? "
<< std::is_nothrow_move_constructible<Ex2>::value << '\n';
}
Saída:
Ex1 is move-constructible? true
Ex1 is trivially move-constructible? false
Ex1 is nothrow move-constructible? true
Ex2 is trivially move-constructible? true
Ex2 is nothrow move-constructible? true