An Entity class to inherit from and bind later.

unbound_pony_entity.py

from __future__ import annotations

from typing import Type, TypeVar, cast

from pony.orm import Database
from pony.orm.core import EntityMeta  # This is a "secret" import


class UnboundEntityMeta(EntityMeta):
    """
    Inert form of EntityMeta.
    """

    def __init__(self):
        """
        Init? I think not!
        """
        object.__init__(self)

    def __new__(cls, *args, **kwargs):
        """
        New? Rejected!
        """
        return type(*args)


class Entity(metaclass=UnboundEntityMeta):
    """
    An bind-able database entity.
    """
    db: Database

    @classmethod
    def bind(cls: EntityImpl, database: Database) -> EntityImpl:
        """
        Bind to a database instance.
        """
        cls.db = database
        return cast(EntityImpl, type(cls.__name__, (database.Entity, ), {**cls.__dict__}))


EntityImpl = TypeVar("EntityImpl", bound=Type[Entity])