removeAll(children) crashes in onRemove

[spydon]

Current bug behavior

If you do removeAll(children) in a component's onRemove method it will assert with:

threw _AssertionError:<'package:flame/src/components/core/component.dart': Failed assertion: line 627 pos 7: 'child._parent != null': Trying to remove a component that doesn't belong to any parent>

Expected behavior

To be able to remove all children in onRemove so that one can do clean-up in there, if you add the children in onMount for example.

Steps to reproduce

      testWithFlameGame(
        'Remove all children in onRemove',
        (game) async {
          final component = _RemoveAllChildrenComponent();
          component.addAll([Component(), Component()]);
          game.add(component);
          await game.ready();
          expect(() => game.remove(component), returnsNormally);
          expect(() => game.update(0), returnsNormally); // Here is the assertion.
        },
      );


class _RemoveAllChildrenComponent extends Component {
  @override
  void onRemove() {
    removeAll(children);
  }
}

More environment information

• Flame version: main

[quentin7b]

Hi there !

I've ran some tests, and according to the doc, onRemove is also called on all the children of the component when you call game.remove(component)

If you add a

class _RemoveWatcherComponent extends Component {
  @override
  void onRemove() {
    debugPrint('onRemove');
    super.onRemove();
  }
}

and transform using component.addAll([Component(), Component()]); you can see that calling game.remove(component) calls onRemove on every child of component before calling onRemove() on the component itself.

It might be because of propagateToChildren in Component#_remove that calls onRemove without calling _remove, therefor putting _parent = null without removing itself from the list of children ?

Is it possible that the issue comes from there ?

[spydon]

It might be because of propagateToChildren in Component#_remove that calls onRemove without calling _remove, therefor putting _parent = null without removing itself from the list of children ?

Is it possible that the issue comes from there ?

Yeah, that's definitely where it comes from. Not sure how to solve it nicely though, because we want the children to have their onRemove called removed before the parent is removed.