std::is_move_constructible, std::is_trivially_move_constructible, std::is_nothrow_move_constructible - cppreference.com

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Definido no cabeçalho `<type_traits>`

`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)

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.

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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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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


	`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


	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`	`bool`

`type`	`std::integral_constant<bool, value>`

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> {};

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

Veja também


is_constructible is_trivially_constructible is_nothrow_constructible (C++11) (C++11) (C++11)	verifica se um tipo tem um construtor para argumentos específicos Original: checks if a type has a constructor for specific arguments The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (modelo de classe) [edit]

is_default_constructible is_trivially_default_constructible is_nothrow_default_constructible (C++11) (C++11) (C++11)	verifica se um tipo tem um construtor padrão Original: checks if a type has a default constructor The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (modelo de classe) [edit]

is_copy_constructible is_trivially_copy_constructible is_nothrow_copy_constructible (C++11) (C++11) (C++11)	verifica se um tipo tem um construtor de cópia Original: checks if a type has a copy constructor The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (modelo de classe) [edit]

move_if_noexcept (C++11)	obtém uma referência rvalue se o construtor movimento não joga Original: obtains an rvalue reference if the move constructor does not throw The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (modelo de função) [edit]