https://github.com/rodydavis/undo/blob/e3b21e2ebe15c462919a3fab5373540de8d27791/lib/src/undo_stack.dart#L89

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

Since the update to undo 1.3.0+1 I cannot undo the first element in the history. The status of the property canUndo is false although the history list still contains an element.

As you can see in the screenshot of the watch _history has one element but canUndo is false and calling the function undo dose not work. it works as expectet in version 1.1.0+1

Hello. There is a bag: My situation:

    var changes = ChangeStack();
    var a = 0;
    var change = Change.inline(() => a++, () => a--);

    changes.group();
    changes.add(change);
    print(a); // 1
    changes.add(change);
    print(a); // 2
    changes.commit();
    print(a); // 4

Situation in your example:

count = 0;

changes.group();

var increase = new Change.inline(() => count++, () => count--);
changes.add(increase);
changes.add(increase);

changes.commit();
print(count); // 2

changes.undo();
print(count); // 0

Plugin: undo 1.1.0+1

Try to fix issue #3 It works well and I don't see any issue like the comment:

  /// Can undo the previous change. If the history is equal to 1 this you cannot undo to null.
  bool get canUndo => _history.isNotEmpty && _history.length > 1;

I am working on an Editor-like app, and I want to show actions history with a description, so I suggest making a getters from the _history and _redos variables.

Sometimes, a user does an operation that triggers a function, but the operation turns out to be invalid, and state is unchanged (at least, as far as a user can tell).

For example, in my application, items can be added in arbitrary positions on a canvas, but they are only valid depending on specific rules. Because I need to loop over a prohibitively large amount of objects, I am reluctant to do a verification pass, then an update pass; I do both at the same time. So the function is what goes in Undo's execute, whether it leads to a meaningful change or not.

In those cases, enabling the undo button is confusing, and pressing it does nothing that the user can see or care about.

if the line https://github.com/rodydavis/undo/blob/master/lib/src/undo_stack.dart#L20 allowed the following:

  void add<T>(Change<T> change) {
    final bool? response = change.execute();
    if(response == false){ 
      return;
     }
    _history.addLast([change]);
    _moveForward();
  }

Then one could optionally return false from the execute function, which would solve my problem.

Line https://github.com/rodydavis/undo/blob/master/lib/src/undo_stack.dart#L88 would need to be changed thusly:

final bool? Function() _execute;

~~None of those changes break any backwards compatibility~~, and they make things more convenient.

Passing lambdas works, but typed named void functions don't, so it is backward compatibility breaking. dynamic works, I'm not acquainted with Dart enough to know if something else works better.

Then, one could write:

changes.add(Change(
  data, 
  (){
     try{
      attemptInsertData();
      return true;
     }catch(e){
      return false;
    }
  }, 
  (old) => data = old
  ));

If you like this change, I can create a PR.