Source code for returns.primitives.exceptions

from __future__ import annotations

from typing import TYPE_CHECKING

    from returns.interfaces.unwrappable import Unwrappable  # noqa: WPS433

[docs]class UnwrapFailedError(Exception): """Raised when a container can not be unwrapped into a meaningful value.""" __slots__ = ('halted_container',) def __init__(self, container: 'Unwrappable') -> None: """ Saves halted container in the inner state. So, this container can later be unpacked from this exception and used as a regular value. """ super().__init__() self.halted_container = container
[docs]class ImmutableStateError(AttributeError): """ Raised when a container is forced to be mutated. It is a sublclass of ``AttributeError`` for two reasons: 1. It seems kinda reasonable to expect ``AttributeError`` on attribute modification 2. It is used inside ```` this way, we do have several typing features that requires that behaviour See: """