Assertion failed: child->parent == this

Development
1

Hi all,

related to this topic, i’ve basically this problem. Here’s basic code:

struct KeyInterceptor : Widget {
	// ...
}

MyWidget(My *module) : ModuleWidget(module) {
	// ...

	// key interceptor
	Vec keyInterceptorTargetRect{pModulePlot->kDragAreaWidth, pModulePlot->kDragAreaHeight};
	keyInterceptor = new KeyInterceptor(module, this, pModulePlot, keyInterceptorTargetRect);
	APP->scene->addChildAbove(keyInterceptor, APP->scene->rackScroll);
}
~MyWidget() {
	if (keyInterceptor) {
		APP->scene->removeChild(keyInterceptor);
		delete keyInterceptor;
	}
}

and happens that when I close Rack, it going in errors, showing to me:

Assertion failed: child->parent == this, file src/widget/Widget.cpp, line 221
make: *** [Makefile:118: run] Error 3

What’s wrong in your opinions? I basically use Rack API to add/remove a child.

Thanks for any tips.

2

I may be wrong; but I believe parents own children… that is: parents manage their children.

You could try removing the manual removeChild and destructor, see if it crashes and see if it leaks.

3

Honestely I would trust the code by the master @stoermelder , which removeChild as well in his destructor.

Ben: do you catch the same error when closing Rack? (after search/show the module on Rack Library).

4

No, I get no error, but I’m using APP->scene->rack as parent. I’m not sure, if it makes any difference.

5

which line in your code is line 221?

6

I think this is the issue, APP->scene->rackScroll is a RackScrollWidget which is different to a RackWidget

is there a reason you want to add your widget to the scroll widget rather than the rack widget?

If you want to add a widget to capture key input; this works for me:

APP->scene->rack->addChild(keyInterceptor);
//---
// destructor
APP->scene->rack->removeChild(keyInterceptor);
delete keyInterceptor;

edit: actually, i think the issue is simply that you are using addChildAbove instead of addChild, this makes keyInterceptor a sibling to APP->scene->rackScroll not a child of it.

1 Like
7

Sometimes it’s better to use widget->requestDelete() instead of parent->removeChild(widget) (then you don’t need to worry about who the parent is).

8

THIS! In fact using add/remove child seems to work well. Can’t do ->rack-> since I need to also intercept ALT button (which is ignored with ->rack->).

I’m play with it and let me see. Thanks