Method __new__

lib/sqlalchemy/orm/util.py:211–246

(
        cls, value_list: Optional[Union[Iterable[str], str]]
    )

    delete_orphan: bool

    def __new__(
        cls, value_list: Optional[Union[Iterable[str], str]]
    ) -> CascadeOptions:
        if isinstance(value_list, str) or value_list is None:
            return cls.from_string(value_list)  # type: ignore
        values = set(value_list)
        if values.difference(cls._allowed_cascades):
            raise sa_exc.ArgumentError(
                "Invalid cascade option(s): %s"
                % ", ".join(
                    [
                        repr(x)
                        for x in sorted(
                            values.difference(cls._allowed_cascades)
                        )
                    ]
                )
            )

        if "all" in values:
            values.update(cls._add_w_all_cascades)
        if "none" in values:
            values.clear()
        values.discard("all")

        self = super().__new__(cls, values)
        self.save_update = "save-update" in values
        self.delete = "delete" in values
        self.refresh_expire = "refresh-expire" in values
        self.merge = "merge" in values
        self.expunge = "expunge" in values
        self.delete_orphan = "delete-orphan" in values

        if self.delete_orphan and not self.delete:
            util.warn("The 'delete-orphan' cascade option requires 'delete'.")
        return self

    def __repr__(self):
        return "CascadeOptions(%r)" % (",".join([x for x in sorted(self)]))