std::promise::set_value_at_thread_exit - cppreference.com (original) (raw)

Main template
void set_value_at_thread_exit( const R& value );	(1)	(since C++11)
void set_value_at_thread_exit( R&& value );	(2)	(since C++11)
std::promise<R&> specializations
void set_value_at_thread_exit( R& value );	(3)	(since C++11)
std::promise<void> specialization
void set_value_at_thread_exit();	(4)	(since C++11)

Stores the value into the shared state without making the state ready immediately. The state is made ready when the current thread exits, after all variables with thread-local storage duration have been destroyed.

The operation behaves as though set_value, set_exception, set_value_at_thread_exit, and set_exception_at_thread_exit acquire a single mutex associated with the promise object while updating the promise object.

Calls to this function do not introduce data races with calls to get_future (therefore they need not synchronize with each other).

[edit] Parameters

value	-	value to store in the shared state

[edit] Return value

(none)

[edit] Exceptions

std::future_error on the following conditions:

*this has no shared state. The error code is set to no_state.
The shared state already stores a value or exception. The error code is set to promise_already_satisfied.

Additionally:

Any exception thrown by the constructor selected to copy an object of type R.
Any exception thrown by the constructor selected to move an object of type R.

[edit] Example

Output:

Waiting... Done! Result is: 9

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.