std::promise<R>::get_future

 

C++

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Technical Specifications

 

Thread support library

Threads
thread (C++11)
hardware_destructive_interference_sizehardware_constructive_interference_size (C++17)(C++17)
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std::promise

Member functions

promise::promise

promise::~promise

promise::operator=

promise::swap

Getting the result

promise::get_future

Setting the result

promise::set_value

promise::set_value_at_thread_exit

promise::set_exception

promise::set_exception_at_thread_exit

 

std::future<T> get_future();		(since C++11)

Returns a future object associated with the same shared state as *this.

An exception is thrown if *this has no shared state or get_future has already been called. To get multiple "pop" ends of the promise-future communication channel, use std::future::share.

Calls to this function do not introduce data races with calls to set_value, set_exception, set_value_at_thread_exit, or set_exception_at_thread_exit (but they need not synchronize with each other).

Parameters

(none)

Return value

A future referring to the shared state of *this

Exceptions

std::future_error on the following conditions:

• *this has no shared state. The error category is set to no_state.

• get_future() has already been called on a promise with the same shared state as *this. The error category is set to future_already_retrieved.