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std::packaged_task - cppreference.com

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Definido no cabeçalho

<future>

template< class > class packaged_task; //not defined

 (1) (desde C++11)

template< class R, class Args... > class packaged_task<R(Args...)>;

 (2) (desde C++11)

O modelo std::packaged_task classe envolve qualquer alvo exigível (função, lambda expressão, expressão bind, ou outro objeto de função), de modo que ele pode ser chamado de forma assíncrona, e seu valor de retorno ou exceção lançada é armazenado no estado compartilhado, que pode ser acessado através std::future objetos.

Original:

The class template std::packaged_task wraps any callable target (function, lambda expression, bind expression, or another function object) so that it can be invoked asynchronously, and its return value or exception thrown is stored in the shared state, which can be accessed through std::future objects.

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Assim como std::function, std::packaged_task é um polimórfico, recipiente alocador-ciente: o alvo armazenados exigível pode ser atribuído, pilha ou com um alocador desde.

Original:

Just like std::function, std::packaged_task is a polymorphic, allocator-aware container: the stored callable target may be allocated on heap or with a provided allocator.

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Funções de membro

constrói o objeto de tarefa

Original:

constructs the task object

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(função pública membro) [edit]

destrói o objeto de tarefa

Original:

destructs the task object

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(função pública membro) [edit]

move o objeto de tarefa

Original:

moves the task object

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(função pública membro) [edit]

Verifica se o objeto tarefa tem uma função válida

Original:

checks if the task object has a valid function

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(função pública membro) [edit]

troca dois objetos de tarefas

Original:

swaps two task objects

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(função pública membro) [edit]

Obtendo o resultado

Original:

Getting the result

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retorna um std::future associado ao resultado prometido

Original:

returns a std::future associated with the promised result

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(função pública membro) [edit]

Execução

Original:

Execution

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executa a função

Original:

executes the function

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(função pública membro) [edit]

executa a função de garantir que o resultado é preparada uma única vez a thread corrente

Original:

executes the function ensuring that the result is ready only once the current thread exits

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(função pública membro) [edit]

redefine o estado abandonar quaisquer resultados armazenados de execuções anteriores

Original:

resets the state abandoning any stored results of previous executions

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(função pública membro) [edit]

Não-membros funções

o algoritmo especializado std::swap

Original:

specializes the std::swap algorithm

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(modelo de função) [edit]

Classes auxiliares

especializa o traço tipo std::uses_allocator

Original:

specializes the std::uses_allocator type trait

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(especialização modelo. classe) [edit]

Exemplo

#include <iostream>
#include <future>
#include <thread>

int main()
{
    std::packaged_task<int()> task([](){return 7;}); // wrap the function
    std::future<int> result = task.get_future();  // get a future
    std::thread(std::move(task)).detach(); // launch on a thread
    std::cout << "Waiting...";
    result.wait();
    std::cout << "Done!\nResult is " << result.get() << '\n';
}

Saída: 

Waiting...Done!
Result is 7

Veja também

espera por um valor que é definido de forma assíncrona

Original:

waits for a value that is set asynchronously

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(modelo de classe) [edit]