type ChildInstructions<
  ChildInstanceType,
  ChildPropsType extends Props,
  ParentPropsType extends Props,
  ParentStateType extends State
> = {
  childClass: new (props: ChildPropsType) => ChildInstanceType;
  instance?: ChildInstanceType;
  propsFactory: (
    parentProps: ParentPropsType,
    parentState: ParentStateType
  ) => ChildPropsType;
};

  children: ChildInstructions<any, any, P, S>[];
  container!: PIXI.Container;

    this.children = []; // child implementation should register child class and props factory in constructor?

    this.children.forEach((child) => {
      child.instance = new child.childClass(
        child.propsFactory(props, this.state)
      );
      this.container.addChild(child.instance.container);
    });

  updateChildren(nextProps: P) {}

  updateChildren(nextProps: P) {
    this.children.forEach(({ instance, propsFactory }) => {
      instance._update(propsFactory(nextProps, this.state));
    });
  }

 * renderChildren?

 * children._update