std::promise<R>:: get_future

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std::promise
std:: future < R > 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 (therefore 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 code is set to no_state .
  • get_future() has already been called on a promise with the same shared state as * this . The error code is set to future_already_retrieved .
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