from typing import ClassVar, Optional


class ModelItem:
    def __new__(cls, *_args, **_kwargs) -> "ModelItem":
        from .model import Model
        cls.parent_model: Optional[Model] = None
        return super().__new__(cls)


    def __setattr__(self, name: str, value) -> None:
        super().__setattr__(name, value)

        if name != "parent_model" and self.parent_model is not None:
            with self.parent_model._sync_lock:
                self.parent_model._changed = True

    def __delattr__(self, name: str) -> None:
        raise NotImplementedError()