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std::weak_ptr

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std::weak_ptr
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Non-member functions
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std::swap
 
Defined in header <memory>
template< class T > class weak_ptr;
(a partir do C++ 11)
std::weak_ptr é um ponteiro inteligente que contém um não-proprietária de referência ("fraco") a um objeto que é gerenciado pelo std::shared_ptr. Ele deve ser convertido para std::shared_ptr para acessar o objeto referenciado.
Original:
std::weak_ptr is a smart pointer that holds a non-owning ("weak") reference to an object that is managed by std::shared_ptr. It must be converted to std::shared_ptr in order to access the referenced object.
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std::weak_ptr modelos de propriedade temporária:. quando um objeto precisa ser acessado somente se ele existe, e ele pode ser excluído a qualquer momento por outra pessoa, std::weak_ptr é usado para rastrear o objeto, e ele é convertido para std::shared_ptr para assumir a propriedade temporária. std::shared_ptr Se o original é destruído neste momento, a vida útil do objeto é prorrogado até o std::shared_ptr temporário é destruído, bem.
Original:
std::weak_ptr models temporary ownership: when an object needs to be accessed only if it exists, and it may be deleted at any time by someone else, std::weak_ptr is used to track the object, and it is converted to std::shared_ptr to assume temporary ownership. If the original std::shared_ptr is destroyed at this time, the object's lifetime is extended until the temporary std::shared_ptr is destroyed as well.
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Além disso, std::weak_ptr é usado para quebrar as referências circulares de std::shared_ptr.
Original:
In addition, std::weak_ptr is used to break circular references of std::shared_ptr.
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Índice

[editar] Tipos de membro

Tipo de membro
Original:
Member type
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Definition
element_type T

[editar] Funções de membro

cria um novo weak_ptr
Original:
creates a new weak_ptr
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(função pública membro) [edit]
destrói uma weak_ptr
Original:
destroys a weak_ptr
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(função pública membro) [edit]
atribui o weak_ptr
Original:
assigns the weak_ptr
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(função pública membro) [edit]
Modificadores
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Modifiers
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libera a propriedade do objeto gerenciado
Original:
releases the ownership of the managed object
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(função pública membro) [edit]
troca os objetos gerenciados
Original:
swaps the managed objects
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(função pública membro) [edit]
Observadores
Original:
Observers
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retorna o número de objetos shared_ptr que gerenciam o objeto
Original:
returns the number of shared_ptr objects that manage the object
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(função pública membro) [edit]
Verifica se o objeto referenciado já foi excluído
Original:
checks whether the referenced object was already deleted
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(função pública membro) [edit]
cria um shared_ptr que gerencia o objeto referenciado
Original:
creates a shared_ptr that manages the referenced object
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(função pública membro) [edit]
fornece-proprietário baseado ordenação dos ponteiros fracos
Original:
provides owner-based ordering of weak pointers
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(função pública membro) [edit]

[editar] Não-membros funções

o algoritmo especializado std::swap
Original:
specializes the std::swap algorithm
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(modelo de função) [edit]

[editar] Exemplo

Demonstra como bloqueio é usado para garantir a validade do ponteiro .
Original:
Demonstrates how lock is used to ensure validity of the pointer.
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#include <iostream>
#include <memory>
 
std::weak_ptr<int> gw;
 
void f()
{
    if (auto spt = gw.lock()) { // Has to be copied into a shared_ptr before usage
	std::cout << *spt << "\n";
    }
    else {
        std::cout << "gw is expired\n";
    }
}
 
int main()
{
    {
        auto sp = std::make_shared<int>(42);
	gw = sp;
 
	f();
    }
 
    f();
}

Output:

42
gw is expired