Why use async function rather than sync ?

[Quanhua-Guan]

undo/lib/src/undo_stack.dart

Line 89 in e3b21e2

final FutureOr<void> Function() _execute;

with redo and undo functions being async function, will it be ok to invoke them inside setState((){}) ?

[Quanhua-Guan]

  /// Notify the framework that the internal state of this object has changed.
  ///
  /// Whenever you change the internal state of a [State] object, make the
  /// change in a function that you pass to [setState]:
  ///
  /// ```dart
  /// setState(() { _myState = newValue; });
  /// ```
  ///
  /// The provided callback is immediately called synchronously. It must not
  /// return a future (the callback cannot be `async`), since then it would be
  /// unclear when the state was actually being set.

[Quanhua-Guan]

undo/example/lib/main.dart

Lines 71 to 73 in e3b21e2

	setState(() {
	_controller.redo();
	});

the _controller.redo() runs asynchronously, the state may not changed when the build method finished.

[rodydavis]

The api I am built is futureOr meaning it is sync or async but I await all incase it is async

[Quanhua-Guan]

The api I am built is futureOr meaning it is sync or async but I await all incase it is async

GOT IT! Thanks! (After Dart 2.0, async function will run synchronously before first 'await', so we can make the redo method runs synchronously)