"""
Represents the base interfaces for types that do fear-some async operations.
This type means that ``FutureResult`` can (and will!) fail with exceptions.
Use this type to mark that this specific async opetaion can fail.
"""
from __future__ import annotations
from abc import abstractmethod
from typing import TYPE_CHECKING, Awaitable, Callable, NoReturn, TypeVar
from returns.interfaces.specific import future, ioresult
from returns.primitives.hkt import KindN
if TYPE_CHECKING:
from returns.future import Future, FutureResult # noqa: WPS433
_FirstType = TypeVar('_FirstType')
_SecondType = TypeVar('_SecondType')
_ThirdType = TypeVar('_ThirdType')
_UpdatedType = TypeVar('_UpdatedType')
_ValueType = TypeVar('_ValueType')
_ErrorType = TypeVar('_ErrorType')
_FutureResultLikeType = TypeVar(
'_FutureResultLikeType', bound='FutureResultLikeN',
)
[docs]class FutureResultLikeN(
future.FutureLikeN[_FirstType, _SecondType, _ThirdType],
ioresult.IOResultLikeN[_FirstType, _SecondType, _ThirdType],
):
"""
Base type for ones that does look like ``FutureResult``.
But at the time this is not a real ``Future`` and cannot be awaited.
It is also cannot be unwrapped, because it is not a real ``IOResult``.
"""
__slots__ = ()
[docs] @abstractmethod
def bind_future_result(
self: _FutureResultLikeType,
function: Callable[
[_FirstType],
FutureResult[_UpdatedType, _SecondType],
],
) -> KindN[_FutureResultLikeType, _UpdatedType, _SecondType, _ThirdType]:
"""Allows to bind ``FutureResult`` functions over a container."""
[docs] @abstractmethod
def bind_async_future_result(
self: _FutureResultLikeType,
function: Callable[
[_FirstType],
Awaitable[FutureResult[_UpdatedType, _SecondType]],
],
) -> KindN[_FutureResultLikeType, _UpdatedType, _SecondType, _ThirdType]:
"""Allows to bind async ``FutureResult`` functions over container."""
[docs] @classmethod
@abstractmethod
def from_failed_future(
cls: type[_FutureResultLikeType], # noqa: N805
inner_value: Future[_ErrorType],
) -> KindN[_FutureResultLikeType, _FirstType, _ErrorType, _ThirdType]:
"""Creates new container from a failed ``Future``."""
[docs] @classmethod
def from_future_result(
cls: type[_FutureResultLikeType], # noqa: N805
inner_value: FutureResult[_ValueType, _ErrorType],
) -> KindN[_FutureResultLikeType, _ValueType, _ErrorType, _ThirdType]:
"""Creates container from ``FutureResult`` instance."""
#: Type alias for kinds with two type arguments.
FutureResultLike2 = FutureResultLikeN[_FirstType, _SecondType, NoReturn]
#: Type alias for kinds with three type arguments.
FutureResultLike3 = FutureResultLikeN[_FirstType, _SecondType, _ThirdType]
[docs]class FutureResultBasedN(
future.FutureBasedN[_FirstType, _SecondType, _ThirdType],
FutureResultLikeN[_FirstType, _SecondType, _ThirdType],
):
"""
Base type for real ``FutureResult`` objects.
They can be awaited.
Still cannot be unwrapped.
"""
__slots__ = ()
#: Type alias for kinds with two type arguments.
FutureResultBased2 = FutureResultBasedN[_FirstType, _SecondType, NoReturn]
#: Type alias for kinds with three type arguments.
FutureResultBased3 = FutureResultBasedN[_FirstType, _SecondType, _ThirdType]