module main

interface IGameObject {
mut:
	name     string
	parent   ?&IGameObject
	children []&IGameObject
	add_child(mut o IGameObject)
	advance()
}

@[heap]
struct GameObject implements IGameObject {
mut:
	name     string
	parent   ?&IGameObject
	children []&IGameObject
}

fn (mut gameobject GameObject) add_child(mut o IGameObject) {
	o.parent = &gameobject
	gameobject.children << o
}

fn (mut gameobject GameObject) advance() {
	if gameobject.parent != none {
		eprintln('parent:  ${gameobject.parent.name} ')
	}
	for mut child in gameobject.children {
		child.advance()
	}
}

fn test_main() {
	mut v1 := &GameObject{
		name: 'v1'
	}
	mut v2 := &GameObject{
		name: 'v2'
	}
	v1.add_child(mut v2)
	v1.advance()
	assert true
}