chore: simplify unwrap_partial (#2590)

* simplify unwrap_partial
* fix async_partial

---------

Signed-off-by: Janek Nouvertné <[email protected]>
Co-authored-by: sourcery-ai[bot] <58596630+sourcery-ai[bot]@users.noreply.github.com>

litestar/utils/helpers.py

@@ -2,6 +2,7 @@
 
 from dataclasses import dataclass
 from enum import Enum
+from functools import partial
 from typing import TYPE_CHECKING, Any, Generic, TypeVar, cast
 from urllib.parse import quote
 
@@ -81,10 +82,9 @@ def unwrap_partial(value: MaybePartial[T]) -> T:
     Returns:
         Callable
     """
-    output: Any = value.func if hasattr(value, "func") else value  # pyright: ignore
-    while hasattr(output, "func"):
-        output = output.func
-    return cast("T", output)
+    from litestar.utils.sync import async_partial
+
+    return cast("T", value.func if isinstance(value, (partial, async_partial)) else value)
 
 
 def filter_cookies(local_cookies: Iterable[Cookie], layered_cookies: Iterable[Cookie]) -> list[Cookie]:

litestar/utils/predicates.py

@@ -4,7 +4,6 @@
 from collections import defaultdict, deque
 from collections.abc import Iterable as CollectionsIterable
 from dataclasses import is_dataclass
-from functools import partial
 from inspect import isasyncgenfunction, isclass, isgeneratorfunction
 from typing import (
     TYPE_CHECKING,
@@ -39,6 +38,7 @@
 from litestar.constants import UNDEFINED_SENTINELS
 from litestar.types import Empty
 from litestar.types.builtin_types import NoneType, UnionTypes
+from litestar.utils.helpers import unwrap_partial
 from litestar.utils.typing import get_origin_or_inner_type
 
 if TYPE_CHECKING:
@@ -86,8 +86,7 @@ class instances with ``async def __call__()`` defined.
     Returns:
         Bool determining if type of ``value`` is an awaitable.
     """
-    while isinstance(value, partial):
-        value = value.func  # type: ignore[unreachable]
+    value = unwrap_partial(value)
 
     return iscoroutinefunction(value) or (
         callable(value) and iscoroutinefunction(value.__call__)  # type: ignore[operator]

litestar/utils/sync.py

@@ -48,9 +48,7 @@ def __init__(self, fn: Callable[P, T]) -> None:
         self._parsed_signature: ParsedSignature | EmptyType = Empty
         self.is_method = ismethod(fn) or (callable(fn) and ismethod(fn.__call__))  # type: ignore
         self.num_expected_args = len(getfullargspec(fn).args) - (1 if self.is_method else 0)
-        self.ref = Ref[Callable[..., Awaitable[T]]](
-            fn if is_async_callable(fn) else async_partial(fn)  # pyright: ignore
-        )
+        self.ref = Ref[Callable[..., Awaitable[T]]](fn if is_async_callable(fn) else async_partial(fn))  # type: ignore
 
     async def __call__(self, *args: P.args, **kwargs: P.kwargs) -> T:
         """Proxy the wrapped function's call method.
@@ -84,25 +82,17 @@ def set_parsed_signature(self, namespace: dict[str, Any]) -> None:
         self._parsed_signature = ParsedSignature.from_fn(unwrap_partial(self.ref.value), namespace)
 
 
-def async_partial(fn: Callable) -> Callable:
+class async_partial:  # noqa: N801
     """Wrap a given sync function making it async.
-
-    In difference to the :func:`asyncio.run_sync` function, it allows for passing kwargs.
-
-    Args:
-        fn: A sync callable to wrap.
-
-    Returns:
-        A wrapper
+    In difference to the :func:`anyio.run_sync` function, it allows for passing kwargs.
     """
 
-    async def wrapper(*args: Any, **kwargs: Any) -> Any:
-        applied_kwarg = partial(fn, **kwargs)
-        return await run_sync(applied_kwarg, *args)
+    def __init__(self, fn: Callable[P, T]) -> None:  # pyright: ignore
+        self.func = fn
 
-    # this allows us to unwrap the partial later, so it's an important "hack".
-    wrapper.func = fn  # type: ignore
-    return wrapper
+    async def __call__(self, *args: P.args, **kwargs: P.kwargs) -> T:  # pyright: ignore
+        applied_kwarg = partial(self.func, **kwargs)
+        return await run_sync(applied_kwarg, *args)  # pyright: ignore
 
 
 class AsyncIteratorWrapper(Generic[T]):

tests/unit/test_utils/test_helpers.py

@@ -1,8 +1,7 @@
 from functools import partial
-from typing import Any, Generic
+from typing import Any, Generic, TypeVar
 
 import pytest
-from typing_extensions import TypeVar
 
 from litestar.utils.helpers import get_name, unique_name_for_scope, unwrap_partial