cpp/thread/promise/get future

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

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

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

Exceptions
std on the following conditions:


 * has no shared state. The error code is set to.


 * has already been called on a promise with the same shared state as . The error code is set to.