Creates a new single-subscription stream from the future.
When the future completes, the stream will fire one event, either data or error, and then close with a done-event.
Source
factory Stream.fromFuture(Future<T> future) { // Use the controller's buffering to fill in the value even before // the stream has a listener. For a single value, it's not worth it // to wait for a listener before doing the `then` on the future. _StreamController<T> controller = new StreamController<T>(sync: true); future.then((value) { controller._add(value); controller._closeUnchecked(); }, onError: (error, stackTrace) { controller._addError(error, stackTrace); controller._closeUnchecked(); }); return controller.stream; }