TYP: Use Self for type checking

Author: topper-123

pandas/_typing.py

@@ -6,6 +6,7 @@
     tzinfo,
 )
 from os import PathLike
+import sys
 from typing import (
     TYPE_CHECKING,
     Any,
@@ -83,8 +84,13 @@
     # Name "npt._ArrayLikeInt_co" is not defined  [name-defined]
     NumpySorter = Optional[npt._ArrayLikeInt_co]  # type: ignore[name-defined]
 
+    if sys.version_info >= (3, 11):
+        from typing import Self
+    else:
+        from typing_extensions import Self  # pyright: reportUnusedImport = false
 else:
     npt: Any = None
+    Self: Any = None
 
 HashableT = TypeVar("HashableT", bound=Hashable)
 

pandas/core/frame.py

@@ -78,11 +78,13 @@
     Level,
     MergeHow,
     NaPosition,
+    NDFrameT,
     PythonFuncType,
     QuantileInterpolation,
     ReadBuffer,
     Renamer,
     Scalar,
+    Self,
     SortKind,
     StorageOptions,
     Suffixes,
@@ -4951,7 +4953,7 @@ def _reindex_multi(
     @doc(NDFrame.align, **_shared_doc_kwargs)
     def align(
         self,
-        other: DataFrame,
+        other: NDFrameT,
         join: AlignJoin = "outer",
         axis: Axis | None = None,
         level: Level = None,
@@ -4961,7 +4963,7 @@ def align(
         limit: int | None = None,
         fill_axis: Axis = 0,
         broadcast_axis: Axis | None = None,
-    ) -> DataFrame:
+    ) -> tuple[Self, NDFrameT]:
         return super().align(
             other,
             join=join,