module main

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

@[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 test_main() {
    mut v1 := &GameObject{
        name: 'v1'
    }
    mut v2 := &GameObject{
        name: 'v2'
    }
    v1.add_child(mut v2)
    for child in v1.children {
        if child.parent != none {
            eprintln('parent: ${child.parent.name}')
        }
    }
    assert true
}