ChangeStackSignalMixin

ChangeStackSignalMixin is a mixin for a Signal that adds undo and redo functionality.

Note

If you are just looking for initial and previous values, use the TrackedSignalMixin.

class MySignal extends Signal<int> with ChangeStackSignalMixin<int> {
  MySignal(int value) : super(value);
}

void main() {
  final signal = MySignal(0);

  signal.value = 1;
  print(signal.canUndo); // true
  signal.undo();
  print(signal.value); // 0
  print(signal.canUndo); // false
  signal.redo();
  print(signal.value); // 1
}

Caution

This mixin only works with values that are immutable or are copied when changed otherwise the initial and previous value will always be the same.

Setting a limit

You can set a limit to the number of changes that can be undone with the limit parameter.

class MySignal extends Signal<int> with ChangeStackSignalMixin<int> {
  MySignal(int value) : super(value);

  @override
  int limit = 3;
}