Future

class Future

Bases: Generic[ResultType]

Future is used for representing an asynchronous computation result.

set_result(result: ResultType) → None

Sets the result of the Future.

Parameters:

result – Result of the Future.

set_exception(exception: Exception, traceback: Optional[TracebackType] = None) → None

Sets the exception for this Future in case of errors.

Parameters:

• exception – Exception to raise in case of error.

• traceback – Traceback of the exception.

result() → ResultType

Returns the result of the Future, which makes the call synchronous if the result has not been computed yet.

Returns:

Result of the Future.

is_success() → bool

Determines whether the result can be successfully computed or not.

done() → bool

Determines whether the result is computed or not.

Returns:

True if the result is computed, False otherwise.

running() → bool

Determines whether the asynchronous call, the computation is still running or not.

Returns:

True if the result is being computed, False otherwise.

exception() → Optional[Exception]

Returns the exceptional result, if any.

Returns:

Exceptional result of this Future.

traceback() → Optional[TracebackType]

Traceback of the exception.

add_done_callback(callback: Callable[[Future], None]) → None

continue_with(continuation_func: Callable[[...], Any], *args: Any) → Future

Create a continuation that executes when the Future is completed.

Parameters:

• continuation_func – A function which takes the Future as the only parameter. Return value of the function will be set as the result of the continuation future. If the return value of the function is another Future, it will be chained to the returned Future.

• *args – Arguments to be passed into continuation_function.

Returns:

A new Future which will be completed when the continuation is done.

combine_futures(futures: Sequence[Future]) → Future

Combines set of Futures.

It waits for the completion of the all input Futures regardless of their output.

The returned Future completes with the list of the results of the input Futures, respecting the input order.

If one of the input Futures completes exceptionally, the returned Future also completes exceptionally. In case of multiple exceptional completions, the returned Future will be completed with the first exceptional result.

Parameters:

futures – List of Futures to be combined.

Returns:

Result of the combination.