From f26031e8c076760afbc163a21ce45bfd4720cff0 Mon Sep 17 00:00:00 2001
From: Terji Petersen <terji78@gmail.com>
Date: Wed, 15 Mar 2023 13:54:07 +0000
Subject: [PATCH] TYP: Use Self instead of class-bound TypeVar
 (generic.py/frame.py/series.py) (#51493)

* TYP: Use Self for type checking

* type frame.py & series.py

* TYP: change Index to Self
---
 pandas/core/frame.py                |   7 +-
 pandas/core/generic.py              | 333 ++++++++++++++--------------
 pandas/core/indexes/base.py         |  67 +++---
 pandas/core/indexes/datetimelike.py |  17 +-
 pandas/core/indexes/extension.py    |   1 -
 pandas/core/series.py               |   5 +-
 6 files changed, 206 insertions(+), 224 deletions(-)

diff --git a/pandas/core/frame.py b/pandas/core/frame.py
index ce4c3d81c4f90..fa2821a6335a3 100644
--- a/pandas/core/frame.py
+++ b/pandas/core/frame.py
@@ -231,6 +231,7 @@
         ReadBuffer,
         Renamer,
         Scalar,
+        Self,
         SortKind,
         StorageOptions,
         Suffixes,
@@ -2495,7 +2496,7 @@ def _from_arrays(
         index,
         dtype: Dtype | None = None,
         verify_integrity: bool = True,
-    ) -> DataFrame:
+    ) -> Self:
         """
         Create DataFrame from a list of arrays corresponding to the columns.
 
@@ -4597,7 +4598,7 @@ def eval(self, expr: str, *, inplace: bool = False, **kwargs) -> Any | None:
 
         return _eval(expr, inplace=inplace, **kwargs)
 
-    def select_dtypes(self, include=None, exclude=None) -> DataFrame:
+    def select_dtypes(self, include=None, exclude=None) -> Self:
         """
         Return a subset of the DataFrame's columns based on the column dtypes.
 
@@ -5015,7 +5016,7 @@ def align(
         limit: int | None = None,
         fill_axis: Axis = 0,
         broadcast_axis: Axis | None = None,
-    ) -> tuple[DataFrame, NDFrameT]:
+    ) -> tuple[Self, NDFrameT]:
         return super().align(
             other,
             join=join,
diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index 17e4a4c142f66..000b0c5d1ff21 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -72,6 +72,7 @@
     RandomState,
     Renamer,
     Scalar,
+    Self,
     SortKind,
     StorageOptions,
     Suffixes,
@@ -311,7 +312,7 @@ def _init_mgr(
                 mgr = mgr.astype(dtype=dtype)
         return mgr
 
-    def _as_manager(self: NDFrameT, typ: str, copy: bool_t = True) -> NDFrameT:
+    def _as_manager(self, typ: str, copy: bool_t = True) -> Self:
         """
         Private helper function to create a DataFrame with specific manager.
 
@@ -400,11 +401,11 @@ def flags(self) -> Flags:
 
     @final
     def set_flags(
-        self: NDFrameT,
+        self,
         *,
         copy: bool_t = False,
         allows_duplicate_labels: bool_t | None = None,
-    ) -> NDFrameT:
+    ) -> Self:
         """
         Return a new object with updated flags.
 
@@ -471,7 +472,7 @@ def _validate_dtype(cls, dtype) -> DtypeObj | None:
     # Construction
 
     @property
-    def _constructor(self: NDFrameT) -> Callable[..., NDFrameT]:
+    def _constructor(self) -> Callable[..., Self]:
         """
         Used when a manipulation result has the same dimensions as the
         original.
@@ -671,12 +672,12 @@ def size(self) -> int:
         return np.prod(self.shape)  # type: ignore[return-value]
 
     def set_axis(
-        self: NDFrameT,
+        self,
         labels,
         *,
         axis: Axis = 0,
         copy: bool_t | None = None,
-    ) -> NDFrameT:
+    ) -> Self:
         """
         Assign desired index to given axis.
 
@@ -732,9 +733,7 @@ def _set_axis(self, axis: AxisInt, labels: AnyArrayLike | list) -> None:
         self._clear_item_cache()
 
     @final
-    def swapaxes(
-        self: NDFrameT, axis1: Axis, axis2: Axis, copy: bool_t | None = None
-    ) -> NDFrameT:
+    def swapaxes(self, axis1: Axis, axis2: Axis, copy: bool_t | None = None) -> Self:
         """
         Interchange axes and swap values axes appropriately.
 
@@ -785,7 +784,7 @@ def swapaxes(
 
     @final
     @doc(klass=_shared_doc_kwargs["klass"])
-    def droplevel(self: NDFrameT, level: IndexLabel, axis: Axis = 0) -> NDFrameT:
+    def droplevel(self, level: IndexLabel, axis: Axis = 0) -> Self:
         """
         Return {klass} with requested index / column level(s) removed.
 
@@ -970,7 +969,7 @@ def squeeze(self, axis: Axis | None = None):
     # Rename
 
     def _rename(
-        self: NDFrameT,
+        self,
         mapper: Renamer | None = None,
         *,
         index: Renamer | None = None,
@@ -980,7 +979,7 @@ def _rename(
         inplace: bool_t = False,
         level: Level | None = None,
         errors: str = "ignore",
-    ) -> NDFrameT | None:
+    ) -> Self | None:
         # called by Series.rename and DataFrame.rename
 
         if mapper is None and index is None and columns is None:
@@ -1042,7 +1041,7 @@ def _rename(
 
     @overload
     def rename_axis(
-        self: NDFrameT,
+        self,
         mapper: IndexLabel | lib.NoDefault = ...,
         *,
         index=...,
@@ -1050,7 +1049,7 @@ def rename_axis(
         axis: Axis = ...,
         copy: bool_t | None = ...,
         inplace: Literal[False] = ...,
-    ) -> NDFrameT:
+    ) -> Self:
         ...
 
     @overload
@@ -1068,7 +1067,7 @@ def rename_axis(
 
     @overload
     def rename_axis(
-        self: NDFrameT,
+        self,
         mapper: IndexLabel | lib.NoDefault = ...,
         *,
         index=...,
@@ -1076,11 +1075,11 @@ def rename_axis(
         axis: Axis = ...,
         copy: bool_t | None = ...,
         inplace: bool_t = ...,
-    ) -> NDFrameT | None:
+    ) -> Self | None:
         ...
 
     def rename_axis(
-        self: NDFrameT,
+        self,
         mapper: IndexLabel | lib.NoDefault = lib.no_default,
         *,
         index=lib.no_default,
@@ -1088,7 +1087,7 @@ def rename_axis(
         axis: Axis = 0,
         copy: bool_t | None = None,
         inplace: bool_t = False,
-    ) -> NDFrameT | None:
+    ) -> Self | None:
         """
         Set the name of the axis for the index or columns.
 
@@ -1419,7 +1418,7 @@ def equals(self, other: object) -> bool_t:
     # Unary Methods
 
     @final
-    def __neg__(self: NDFrameT) -> NDFrameT:
+    def __neg__(self) -> Self:
         def blk_func(values: ArrayLike):
             if is_bool_dtype(values.dtype):
                 # error: Argument 1 to "inv" has incompatible type "Union
@@ -1437,7 +1436,7 @@ def blk_func(values: ArrayLike):
         return res.__finalize__(self, method="__neg__")
 
     @final
-    def __pos__(self: NDFrameT) -> NDFrameT:
+    def __pos__(self) -> Self:
         def blk_func(values: ArrayLike):
             if is_bool_dtype(values.dtype):
                 return values.copy()
@@ -1452,7 +1451,7 @@ def blk_func(values: ArrayLike):
         return res.__finalize__(self, method="__pos__")
 
     @final
-    def __invert__(self: NDFrameT) -> NDFrameT:
+    def __invert__(self) -> Self:
         if not self.size:
             # inv fails with 0 len
             return self.copy(deep=False)
@@ -1517,7 +1516,7 @@ def bool(self) -> bool_t:
         return True
 
     @final
-    def abs(self: NDFrameT) -> NDFrameT:
+    def abs(self) -> Self:
         """
         Return a Series/DataFrame with absolute numeric value of each element.
 
@@ -1588,11 +1587,11 @@ def abs(self: NDFrameT) -> NDFrameT:
         return self._constructor(res_mgr).__finalize__(self, name="abs")
 
     @final
-    def __abs__(self: NDFrameT) -> NDFrameT:
+    def __abs__(self) -> Self:
         return self.abs()
 
     @final
-    def __round__(self: NDFrameT, decimals: int = 0) -> NDFrameT:
+    def __round__(self, decimals: int = 0) -> Self:
         return self.round(decimals).__finalize__(self, method="__round__")
 
     # -------------------------------------------------------------------------
@@ -3822,7 +3821,7 @@ def _clear_item_cache(self) -> None:
     # Indexing Methods
 
     @final
-    def take(self: NDFrameT, indices, axis: Axis = 0, **kwargs) -> NDFrameT:
+    def take(self, indices, axis: Axis = 0, **kwargs) -> Self:
         """
         Return the elements in the given *positional* indices along an axis.
 
@@ -3936,7 +3935,7 @@ class  max_speed
         return self._constructor(new_data).__finalize__(self, method="take")
 
     @final
-    def _take_with_is_copy(self: NDFrameT, indices, axis: Axis = 0) -> NDFrameT:
+    def _take_with_is_copy(self, indices, axis: Axis = 0) -> Self:
         """
         Internal version of the `take` method that sets the `_is_copy`
         attribute to keep track of the parent dataframe (using in indexing
@@ -3954,12 +3953,12 @@ def _take_with_is_copy(self: NDFrameT, indices, axis: Axis = 0) -> NDFrameT:
 
     @final
     def xs(
-        self: NDFrameT,
+        self,
         key: IndexLabel,
         axis: Axis = 0,
         level: IndexLabel = None,
         drop_level: bool_t = True,
-    ) -> NDFrameT:
+    ) -> Self:
         """
         Return cross-section from the Series/DataFrame.
 
@@ -4134,7 +4133,7 @@ class   animal   locomotion
     def __getitem__(self, item):
         raise AbstractMethodError(self)
 
-    def _slice(self: NDFrameT, slobj: slice, axis: Axis = 0) -> NDFrameT:
+    def _slice(self, slobj: slice, axis: Axis = 0) -> Self:
         """
         Construct a slice of this container.
 
@@ -4364,13 +4363,13 @@ def _is_view(self) -> bool_t:
 
     @final
     def reindex_like(
-        self: NDFrameT,
+        self,
         other,
         method: Literal["backfill", "bfill", "pad", "ffill", "nearest"] | None = None,
         copy: bool_t | None = None,
         limit=None,
         tolerance=None,
-    ) -> NDFrameT:
+    ) -> Self:
         """
         Return an object with matching indices as other object.
 
@@ -4490,7 +4489,7 @@ def drop(
 
     @overload
     def drop(
-        self: NDFrameT,
+        self,
         labels: IndexLabel = ...,
         *,
         axis: Axis = ...,
@@ -4499,12 +4498,12 @@ def drop(
         level: Level | None = ...,
         inplace: Literal[False] = ...,
         errors: IgnoreRaise = ...,
-    ) -> NDFrameT:
+    ) -> Self:
         ...
 
     @overload
     def drop(
-        self: NDFrameT,
+        self,
         labels: IndexLabel = ...,
         *,
         axis: Axis = ...,
@@ -4513,11 +4512,11 @@ def drop(
         level: Level | None = ...,
         inplace: bool_t = ...,
         errors: IgnoreRaise = ...,
-    ) -> NDFrameT | None:
+    ) -> Self | None:
         ...
 
     def drop(
-        self: NDFrameT,
+        self,
         labels: IndexLabel = None,
         *,
         axis: Axis = 0,
@@ -4526,7 +4525,7 @@ def drop(
         level: Level | None = None,
         inplace: bool_t = False,
         errors: IgnoreRaise = "raise",
-    ) -> NDFrameT | None:
+    ) -> Self | None:
         inplace = validate_bool_kwarg(inplace, "inplace")
 
         if labels is not None:
@@ -4557,13 +4556,13 @@ def drop(
 
     @final
     def _drop_axis(
-        self: NDFrameT,
+        self,
         labels,
         axis,
         level=None,
         errors: IgnoreRaise = "raise",
         only_slice: bool_t = False,
-    ) -> NDFrameT:
+    ) -> Self:
         """
         Drop labels from specified axis. Used in the ``drop`` method
         internally.
@@ -4661,7 +4660,7 @@ def _update_inplace(self, result, verify_is_copy: bool_t = True) -> None:
         self._maybe_update_cacher(verify_is_copy=verify_is_copy, inplace=True)
 
     @final
-    def add_prefix(self: NDFrameT, prefix: str, axis: Axis | None = None) -> NDFrameT:
+    def add_prefix(self, prefix: str, axis: Axis | None = None) -> Self:
         """
         Prefix labels with string `prefix`.
 
@@ -4727,15 +4726,15 @@ def add_prefix(self: NDFrameT, prefix: str, axis: Axis | None = None) -> NDFrame
 
         mapper = {axis_name: f}
 
-        # error: Incompatible return value type (got "Optional[NDFrameT]",
-        # expected "NDFrameT")
+        # error: Incompatible return value type (got "Optional[Self]",
+        # expected "Self")
         # error: Argument 1 to "rename" of "NDFrame" has incompatible type
         # "**Dict[str, partial[str]]"; expected "Union[str, int, None]"
         # error: Keywords must be strings
         return self._rename(**mapper)  # type: ignore[return-value, arg-type, misc]
 
     @final
-    def add_suffix(self: NDFrameT, suffix: str, axis: Axis | None = None) -> NDFrameT:
+    def add_suffix(self, suffix: str, axis: Axis | None = None) -> Self:
         """
         Suffix labels with string `suffix`.
 
@@ -4800,8 +4799,8 @@ def add_suffix(self: NDFrameT, suffix: str, axis: Axis | None = None) -> NDFrame
             axis_name = self._get_axis_name(axis)
 
         mapper = {axis_name: f}
-        # error: Incompatible return value type (got "Optional[NDFrameT]",
-        # expected "NDFrameT")
+        # error: Incompatible return value type (got "Optional[Self]",
+        # expected "Self")
         # error: Argument 1 to "rename" of "NDFrame" has incompatible type
         # "**Dict[str, partial[str]]"; expected "Union[str, int, None]"
         # error: Keywords must be strings
@@ -4809,7 +4808,7 @@ def add_suffix(self: NDFrameT, suffix: str, axis: Axis | None = None) -> NDFrame
 
     @overload
     def sort_values(
-        self: NDFrameT,
+        self,
         *,
         axis: Axis = ...,
         ascending: bool_t | Sequence[bool_t] = ...,
@@ -4818,7 +4817,7 @@ def sort_values(
         na_position: str = ...,
         ignore_index: bool_t = ...,
         key: ValueKeyFunc = ...,
-    ) -> NDFrameT:
+    ) -> Self:
         ...
 
     @overload
@@ -4837,7 +4836,7 @@ def sort_values(
 
     @overload
     def sort_values(
-        self: NDFrameT,
+        self,
         *,
         axis: Axis = ...,
         ascending: bool_t | Sequence[bool_t] = ...,
@@ -4846,11 +4845,11 @@ def sort_values(
         na_position: str = ...,
         ignore_index: bool_t = ...,
         key: ValueKeyFunc = ...,
-    ) -> NDFrameT | None:
+    ) -> Self | None:
         ...
 
     def sort_values(
-        self: NDFrameT,
+        self,
         *,
         axis: Axis = 0,
         ascending: bool_t | Sequence[bool_t] = True,
@@ -4859,7 +4858,7 @@ def sort_values(
         na_position: str = "last",
         ignore_index: bool_t = False,
         key: ValueKeyFunc = None,
-    ) -> NDFrameT | None:
+    ) -> Self | None:
         """
         Sort by the values along either axis.
 
@@ -5021,7 +5020,7 @@ def sort_index(
 
     @overload
     def sort_index(
-        self: NDFrameT,
+        self,
         *,
         axis: Axis = ...,
         level: IndexLabel = ...,
@@ -5032,12 +5031,12 @@ def sort_index(
         sort_remaining: bool_t = ...,
         ignore_index: bool_t = ...,
         key: IndexKeyFunc = ...,
-    ) -> NDFrameT:
+    ) -> Self:
         ...
 
     @overload
     def sort_index(
-        self: NDFrameT,
+        self,
         *,
         axis: Axis = ...,
         level: IndexLabel = ...,
@@ -5048,11 +5047,11 @@ def sort_index(
         sort_remaining: bool_t = ...,
         ignore_index: bool_t = ...,
         key: IndexKeyFunc = ...,
-    ) -> NDFrameT | None:
+    ) -> Self | None:
         ...
 
     def sort_index(
-        self: NDFrameT,
+        self,
         *,
         axis: Axis = 0,
         level: IndexLabel = None,
@@ -5063,7 +5062,7 @@ def sort_index(
         sort_remaining: bool_t = True,
         ignore_index: bool_t = False,
         key: IndexKeyFunc = None,
-    ) -> NDFrameT | None:
+    ) -> Self | None:
         inplace = validate_bool_kwarg(inplace, "inplace")
         axis = self._get_axis_number(axis)
         ascending = validate_ascending(ascending)
@@ -5109,7 +5108,7 @@ def sort_index(
         optional_reindex="",
     )
     def reindex(
-        self: NDFrameT,
+        self,
         labels=None,
         index=None,
         columns=None,
@@ -5120,7 +5119,7 @@ def reindex(
         fill_value: Scalar | None = np.nan,
         limit: int | None = None,
         tolerance=None,
-    ) -> NDFrameT:
+    ) -> Self:
         """
         Conform {klass} to new index with optional filling logic.
 
@@ -5363,8 +5362,8 @@ def reindex(
         ).__finalize__(self, method="reindex")
 
     def _reindex_axes(
-        self: NDFrameT, axes, level, limit, tolerance, method, fill_value, copy
-    ) -> NDFrameT:
+        self, axes, level, limit, tolerance, method, fill_value, copy
+    ) -> Self:
         """Perform the reindex for all the axes."""
         obj = self
         for a in self._AXIS_ORDERS:
@@ -5408,12 +5407,12 @@ def _reindex_multi(self, axes, copy, fill_value):
 
     @final
     def _reindex_with_indexers(
-        self: NDFrameT,
+        self,
         reindexers,
         fill_value=None,
         copy: bool_t | None = False,
         allow_dups: bool_t = False,
-    ) -> NDFrameT:
+    ) -> Self:
         """allow_dups indicates an internal call here"""
         # reindex doing multiple operations on different axes if indicated
         new_data = self._mgr
@@ -5452,12 +5451,12 @@ def _reindex_with_indexers(
         return self._constructor(new_data).__finalize__(self)
 
     def filter(
-        self: NDFrameT,
+        self,
         items=None,
         like: str | None = None,
         regex: str | None = None,
         axis: Axis | None = None,
-    ) -> NDFrameT:
+    ) -> Self:
         """
         Subset the dataframe rows or columns according to the specified index labels.
 
@@ -5558,7 +5557,7 @@ def f(x) -> bool_t:
             raise TypeError("Must pass either `items`, `like`, or `regex`")
 
     @final
-    def head(self: NDFrameT, n: int = 5) -> NDFrameT:
+    def head(self, n: int = 5) -> Self:
         """
         Return the first `n` rows.
 
@@ -5633,7 +5632,7 @@ def head(self: NDFrameT, n: int = 5) -> NDFrameT:
         return self.iloc[:n]
 
     @final
-    def tail(self: NDFrameT, n: int = 5) -> NDFrameT:
+    def tail(self, n: int = 5) -> Self:
         """
         Return the last `n` rows.
 
@@ -5711,7 +5710,7 @@ def tail(self: NDFrameT, n: int = 5) -> NDFrameT:
 
     @final
     def sample(
-        self: NDFrameT,
+        self,
         n: int | None = None,
         frac: float | None = None,
         replace: bool_t = False,
@@ -5719,7 +5718,7 @@ def sample(
         random_state: RandomState | None = None,
         axis: Axis | None = None,
         ignore_index: bool_t = False,
-    ) -> NDFrameT:
+    ) -> Self:
         """
         Return a random sample of items from an axis of object.
 
@@ -5975,9 +5974,7 @@ def pipe(
     # Attribute access
 
     @final
-    def __finalize__(
-        self: NDFrameT, other, method: str | None = None, **kwargs
-    ) -> NDFrameT:
+    def __finalize__(self, other, method: str | None = None, **kwargs) -> Self:
         """
         Propagate metadata from other to self.
 
@@ -6154,7 +6151,7 @@ def _check_inplace_setting(self, value) -> bool_t:
         return True
 
     @final
-    def _get_numeric_data(self: NDFrameT) -> NDFrameT:
+    def _get_numeric_data(self) -> Self:
         return self._constructor(self._mgr.get_numeric_data()).__finalize__(self)
 
     @final
@@ -6205,8 +6202,8 @@ def dtypes(self):
         return self._constructor_sliced(data, index=self._info_axis, dtype=np.object_)
 
     def astype(
-        self: NDFrameT, dtype, copy: bool_t | None = None, errors: IgnoreRaise = "raise"
-    ) -> NDFrameT:
+        self, dtype, copy: bool_t | None = None, errors: IgnoreRaise = "raise"
+    ) -> Self:
         """
         Cast a pandas object to a specified dtype ``dtype``.
 
@@ -6378,15 +6375,15 @@ def astype(
         result = concat(results, axis=1, copy=False)
         # GH#40810 retain subclass
         # error: Incompatible types in assignment
-        # (expression has type "NDFrameT", variable has type "DataFrame")
+        # (expression has type "Self", variable has type "DataFrame")
         result = self._constructor(result)  # type: ignore[assignment]
         result.columns = self.columns
         result = result.__finalize__(self, method="astype")
         # https://github.com/python/mypy/issues/8354
-        return cast(NDFrameT, result)
+        return cast(Self, result)
 
     @final
-    def copy(self: NDFrameT, deep: bool_t | None = True) -> NDFrameT:
+    def copy(self, deep: bool_t | None = True) -> Self:
         """
         Make a copy of this object's indices and data.
 
@@ -6500,11 +6497,11 @@ def copy(self: NDFrameT, deep: bool_t | None = True) -> NDFrameT:
         return self._constructor(data).__finalize__(self, method="copy")
 
     @final
-    def __copy__(self: NDFrameT, deep: bool_t = True) -> NDFrameT:
+    def __copy__(self, deep: bool_t = True) -> Self:
         return self.copy(deep=deep)
 
     @final
-    def __deepcopy__(self: NDFrameT, memo=None) -> NDFrameT:
+    def __deepcopy__(self, memo=None) -> Self:
         """
         Parameters
         ----------
@@ -6514,7 +6511,7 @@ def __deepcopy__(self: NDFrameT, memo=None) -> NDFrameT:
         return self.copy(deep=True)
 
     @final
-    def infer_objects(self: NDFrameT, copy: bool_t | None = None) -> NDFrameT:
+    def infer_objects(self, copy: bool_t | None = None) -> Self:
         """
         Attempt to infer better dtypes for object columns.
 
@@ -6563,14 +6560,14 @@ def infer_objects(self: NDFrameT, copy: bool_t | None = None) -> NDFrameT:
 
     @final
     def convert_dtypes(
-        self: NDFrameT,
+        self,
         infer_objects: bool_t = True,
         convert_string: bool_t = True,
         convert_integer: bool_t = True,
         convert_boolean: bool_t = True,
         convert_floating: bool_t = True,
         dtype_backend: DtypeBackend = "numpy_nullable",
-    ) -> NDFrameT:
+    ) -> Self:
         """
         Convert columns to the best possible dtypes using dtypes supporting ``pd.NA``.
 
@@ -6739,7 +6736,7 @@ def convert_dtypes(
                 result = cons(result)
                 result = result.__finalize__(self, method="convert_dtypes")
                 # https://github.com/python/mypy/issues/8354
-                return cast(NDFrameT, result)
+                return cast(Self, result)
             else:
                 return self.copy(deep=None)
 
@@ -6748,7 +6745,7 @@ def convert_dtypes(
 
     @overload
     def fillna(
-        self: NDFrameT,
+        self,
         value: Hashable | Mapping | Series | DataFrame = ...,
         *,
         method: FillnaOptions | None = ...,
@@ -6756,7 +6753,7 @@ def fillna(
         inplace: Literal[False] = ...,
         limit: int | None = ...,
         downcast: dict | None = ...,
-    ) -> NDFrameT:
+    ) -> Self:
         ...
 
     @overload
@@ -6774,7 +6771,7 @@ def fillna(
 
     @overload
     def fillna(
-        self: NDFrameT,
+        self,
         value: Hashable | Mapping | Series | DataFrame = ...,
         *,
         method: FillnaOptions | None = ...,
@@ -6782,12 +6779,12 @@ def fillna(
         inplace: bool_t = ...,
         limit: int | None = ...,
         downcast: dict | None = ...,
-    ) -> NDFrameT | None:
+    ) -> Self | None:
         ...
 
     @doc(**_shared_doc_kwargs)
     def fillna(
-        self: NDFrameT,
+        self,
         value: Hashable | Mapping | Series | DataFrame = None,
         *,
         method: FillnaOptions | None = None,
@@ -6795,7 +6792,7 @@ def fillna(
         inplace: bool_t = False,
         limit: int | None = None,
         downcast: dict | None = None,
-    ) -> NDFrameT | None:
+    ) -> Self | None:
         """
         Fill NA/NaN values using the specified method.
 
@@ -7049,13 +7046,13 @@ def fillna(
 
     @overload
     def ffill(
-        self: NDFrameT,
+        self,
         *,
         axis: None | Axis = ...,
         inplace: Literal[False] = ...,
         limit: None | int = ...,
         downcast: dict | None = ...,
-    ) -> NDFrameT:
+    ) -> Self:
         ...
 
     @overload
@@ -7071,24 +7068,24 @@ def ffill(
 
     @overload
     def ffill(
-        self: NDFrameT,
+        self,
         *,
         axis: None | Axis = ...,
         inplace: bool_t = ...,
         limit: None | int = ...,
         downcast: dict | None = ...,
-    ) -> NDFrameT | None:
+    ) -> Self | None:
         ...
 
     @doc(klass=_shared_doc_kwargs["klass"])
     def ffill(
-        self: NDFrameT,
+        self,
         *,
         axis: None | Axis = None,
         inplace: bool_t = False,
         limit: None | int = None,
         downcast: dict | None = None,
-    ) -> NDFrameT | None:
+    ) -> Self | None:
         """
         Synonym for :meth:`DataFrame.fillna` with ``method='ffill'``.
 
@@ -7103,13 +7100,13 @@ def ffill(
 
     @doc(klass=_shared_doc_kwargs["klass"])
     def pad(
-        self: NDFrameT,
+        self,
         *,
         axis: None | Axis = None,
         inplace: bool_t = False,
         limit: None | int = None,
         downcast: dict | None = None,
-    ) -> NDFrameT | None:
+    ) -> Self | None:
         """
         Synonym for :meth:`DataFrame.fillna` with ``method='ffill'``.
 
@@ -7132,13 +7129,13 @@ def pad(
 
     @overload
     def bfill(
-        self: NDFrameT,
+        self,
         *,
         axis: None | Axis = ...,
         inplace: Literal[False] = ...,
         limit: None | int = ...,
         downcast: dict | None = ...,
-    ) -> NDFrameT:
+    ) -> Self:
         ...
 
     @overload
@@ -7154,24 +7151,24 @@ def bfill(
 
     @overload
     def bfill(
-        self: NDFrameT,
+        self,
         *,
         axis: None | Axis = ...,
         inplace: bool_t = ...,
         limit: None | int = ...,
         downcast: dict | None = ...,
-    ) -> NDFrameT | None:
+    ) -> Self | None:
         ...
 
     @doc(klass=_shared_doc_kwargs["klass"])
     def bfill(
-        self: NDFrameT,
+        self,
         *,
         axis: None | Axis = None,
         inplace: bool_t = False,
         limit: None | int = None,
         downcast: dict | None = None,
-    ) -> NDFrameT | None:
+    ) -> Self | None:
         """
         Synonym for :meth:`DataFrame.fillna` with ``method='bfill'``.
 
@@ -7186,13 +7183,13 @@ def bfill(
 
     @doc(klass=_shared_doc_kwargs["klass"])
     def backfill(
-        self: NDFrameT,
+        self,
         *,
         axis: None | Axis = None,
         inplace: bool_t = False,
         limit: None | int = None,
         downcast: dict | None = None,
-    ) -> NDFrameT | None:
+    ) -> Self | None:
         """
         Synonym for :meth:`DataFrame.fillna` with ``method='bfill'``.
 
@@ -7215,7 +7212,7 @@ def backfill(
 
     @overload
     def replace(
-        self: NDFrameT,
+        self,
         to_replace=...,
         value=...,
         *,
@@ -7223,7 +7220,7 @@ def replace(
         limit: int | None = ...,
         regex: bool_t = ...,
         method: Literal["pad", "ffill", "bfill"] | lib.NoDefault = ...,
-    ) -> NDFrameT:
+    ) -> Self:
         ...
 
     @overload
@@ -7241,7 +7238,7 @@ def replace(
 
     @overload
     def replace(
-        self: NDFrameT,
+        self,
         to_replace=...,
         value=...,
         *,
@@ -7249,7 +7246,7 @@ def replace(
         limit: int | None = ...,
         regex: bool_t = ...,
         method: Literal["pad", "ffill", "bfill"] | lib.NoDefault = ...,
-    ) -> NDFrameT | None:
+    ) -> Self | None:
         ...
 
     @doc(
@@ -7259,7 +7256,7 @@ def replace(
         replace_iloc=_shared_doc_kwargs["replace_iloc"],
     )
     def replace(
-        self: NDFrameT,
+        self,
         to_replace=None,
         value=lib.no_default,
         *,
@@ -7267,7 +7264,7 @@ def replace(
         limit: int | None = None,
         regex: bool_t = False,
         method: Literal["pad", "ffill", "bfill"] | lib.NoDefault = lib.no_default,
-    ) -> NDFrameT | None:
+    ) -> Self | None:
         if not (
             is_scalar(to_replace)
             or is_re_compilable(to_replace)
@@ -7454,7 +7451,7 @@ def replace(
             return result.__finalize__(self, method="replace")
 
     def interpolate(
-        self: NDFrameT,
+        self,
         method: str = "linear",
         *,
         axis: Axis = 0,
@@ -7464,7 +7461,7 @@ def interpolate(
         limit_area: str | None = None,
         downcast: str | None = None,
         **kwargs,
-    ) -> NDFrameT | None:
+    ) -> Self | None:
         """
         Fill NaN values using an interpolation method.
 
@@ -7929,7 +7926,7 @@ def asof(self, where, subset=None):
     # Action Methods
 
     @doc(klass=_shared_doc_kwargs["klass"])
-    def isna(self: NDFrameT) -> NDFrameT:
+    def isna(self) -> Self:
         """
         Detect missing values.
 
@@ -7992,11 +7989,11 @@ def isna(self: NDFrameT) -> NDFrameT:
         return isna(self).__finalize__(self, method="isna")
 
     @doc(isna, klass=_shared_doc_kwargs["klass"])
-    def isnull(self: NDFrameT) -> NDFrameT:
+    def isnull(self) -> Self:
         return isna(self).__finalize__(self, method="isnull")
 
     @doc(klass=_shared_doc_kwargs["klass"])
-    def notna(self: NDFrameT) -> NDFrameT:
+    def notna(self) -> Self:
         """
         Detect existing (non-missing) values.
 
@@ -8059,7 +8056,7 @@ def notna(self: NDFrameT) -> NDFrameT:
         return notna(self).__finalize__(self, method="notna")
 
     @doc(notna, klass=_shared_doc_kwargs["klass"])
-    def notnull(self: NDFrameT) -> NDFrameT:
+    def notnull(self) -> Self:
         return notna(self).__finalize__(self, method="notnull")
 
     @final
@@ -8120,14 +8117,14 @@ def _clip_with_one_bound(self, threshold, method, axis, inplace):
         return self.where(subset, threshold, axis=axis, inplace=inplace)
 
     def clip(
-        self: NDFrameT,
+        self,
         lower=None,
         upper=None,
         *,
         axis: Axis | None = None,
         inplace: bool_t = False,
         **kwargs,
-    ) -> NDFrameT | None:
+    ) -> Self | None:
         """
         Trim values at input threshold(s).
 
@@ -8281,13 +8278,13 @@ def clip(
 
     @doc(**_shared_doc_kwargs)
     def asfreq(
-        self: NDFrameT,
+        self,
         freq: Frequency,
         method: FillnaOptions | None = None,
         how: str | None = None,
         normalize: bool_t = False,
         fill_value: Hashable = None,
-    ) -> NDFrameT:
+    ) -> Self:
         """
         Convert time series to specified frequency.
 
@@ -8405,9 +8402,7 @@ def asfreq(
         )
 
     @final
-    def at_time(
-        self: NDFrameT, time, asof: bool_t = False, axis: Axis | None = None
-    ) -> NDFrameT:
+    def at_time(self, time, asof: bool_t = False, axis: Axis | None = None) -> Self:
         """
         Select values at particular time of day (e.g., 9:30AM).
 
@@ -8465,12 +8460,12 @@ def at_time(
 
     @final
     def between_time(
-        self: NDFrameT,
+        self,
         start_time,
         end_time,
         inclusive: IntervalClosedType = "both",
         axis: Axis | None = None,
-    ) -> NDFrameT:
+    ) -> Self:
         """
         Select values between particular times of the day (e.g., 9:00-9:30 AM).
 
@@ -8949,7 +8944,7 @@ def resample(
         )
 
     @final
-    def first(self: NDFrameT, offset) -> NDFrameT:
+    def first(self, offset) -> Self:
         """
         Select initial periods of time series data based on a date offset.
 
@@ -9022,7 +9017,7 @@ def first(self: NDFrameT, offset) -> NDFrameT:
         return self.loc[:end]
 
     @final
-    def last(self: NDFrameT, offset) -> NDFrameT:
+    def last(self, offset) -> Self:
         """
         Select final periods of time series data based on a date offset.
 
@@ -9087,14 +9082,14 @@ def last(self: NDFrameT, offset) -> NDFrameT:
 
     @final
     def rank(
-        self: NDFrameT,
+        self,
         axis: Axis = 0,
         method: str = "average",
         numeric_only: bool_t = False,
         na_option: str = "keep",
         ascending: bool_t = True,
         pct: bool_t = False,
-    ) -> NDFrameT:
+    ) -> Self:
         """
         Compute numerical data ranks (1 through n) along axis.
 
@@ -9317,8 +9312,8 @@ def compare(
 
     @doc(**_shared_doc_kwargs)
     def align(
-        self: NDFrameT,
-        other: NDFrameTb,
+        self,
+        other: NDFrameT,
         join: AlignJoin = "outer",
         axis: Axis | None = None,
         level: Level = None,
@@ -9328,7 +9323,7 @@ def align(
         limit: int | None = None,
         fill_axis: Axis = 0,
         broadcast_axis: Axis | None = None,
-    ) -> tuple[NDFrameT, NDFrameTb]:
+    ) -> tuple[Self, NDFrameT]:
         """
         Align two objects on their axes with the specified join method.
 
@@ -9802,14 +9797,14 @@ def _where(
 
     @overload
     def where(
-        self: NDFrameT,
+        self,
         cond,
         other=...,
         *,
         inplace: Literal[False] = ...,
         axis: Axis | None = ...,
         level: Level = ...,
-    ) -> NDFrameT:
+    ) -> Self:
         ...
 
     @overload
@@ -9826,14 +9821,14 @@ def where(
 
     @overload
     def where(
-        self: NDFrameT,
+        self,
         cond,
         other=...,
         *,
         inplace: bool_t = ...,
         axis: Axis | None = ...,
         level: Level = ...,
-    ) -> NDFrameT | None:
+    ) -> Self | None:
         ...
 
     @doc(
@@ -9844,14 +9839,14 @@ def where(
         name_other="mask",
     )
     def where(
-        self: NDFrameT,
+        self,
         cond,
         other=np.nan,
         *,
         inplace: bool_t = False,
         axis: Axis | None = None,
         level: Level = None,
-    ) -> NDFrameT | None:
+    ) -> Self | None:
         """
         Replace values where the condition is {cond_rev}.
 
@@ -9994,14 +9989,14 @@ def where(
 
     @overload
     def mask(
-        self: NDFrameT,
+        self,
         cond,
         other=...,
         *,
         inplace: Literal[False] = ...,
         axis: Axis | None = ...,
         level: Level = ...,
-    ) -> NDFrameT:
+    ) -> Self:
         ...
 
     @overload
@@ -10018,14 +10013,14 @@ def mask(
 
     @overload
     def mask(
-        self: NDFrameT,
+        self,
         cond,
         other=...,
         *,
         inplace: bool_t = ...,
         axis: Axis | None = ...,
         level: Level = ...,
-    ) -> NDFrameT | None:
+    ) -> Self | None:
         ...
 
     @doc(
@@ -10037,14 +10032,14 @@ def mask(
         name_other="where",
     )
     def mask(
-        self: NDFrameT,
+        self,
         cond,
         other=lib.no_default,
         *,
         inplace: bool_t = False,
         axis: Axis | None = None,
         level: Level = None,
-    ) -> NDFrameT | None:
+    ) -> Self | None:
         inplace = validate_bool_kwarg(inplace, "inplace")
         cond = common.apply_if_callable(cond, self)
 
@@ -10062,12 +10057,12 @@ def mask(
 
     @doc(klass=_shared_doc_kwargs["klass"])
     def shift(
-        self: NDFrameT,
+        self,
         periods: int = 1,
         freq=None,
         axis: Axis = 0,
         fill_value: Hashable = None,
-    ) -> NDFrameT:
+    ) -> Self:
         """
         Shift index by desired number of periods with an optional time `freq`.
 
@@ -10209,12 +10204,12 @@ def shift(
         return result.__finalize__(self, method="shift")
 
     def truncate(
-        self: NDFrameT,
+        self,
         before=None,
         after=None,
         axis: Axis | None = None,
         copy: bool_t | None = None,
-    ) -> NDFrameT:
+    ) -> Self:
         """
         Truncate a Series or DataFrame before and after some index value.
 
@@ -10371,8 +10366,8 @@ def truncate(
     @final
     @doc(klass=_shared_doc_kwargs["klass"])
     def tz_convert(
-        self: NDFrameT, tz, axis: Axis = 0, level=None, copy: bool_t | None = None
-    ) -> NDFrameT:
+        self, tz, axis: Axis = 0, level=None, copy: bool_t | None = None
+    ) -> Self:
         """
         Convert tz-aware axis to target time zone.
 
@@ -10452,14 +10447,14 @@ def _tz_convert(ax, tz):
     @final
     @doc(klass=_shared_doc_kwargs["klass"])
     def tz_localize(
-        self: NDFrameT,
+        self,
         tz,
         axis: Axis = 0,
         level=None,
         copy: bool_t | None = None,
         ambiguous: TimeAmbiguous = "raise",
         nonexistent: TimeNonexistent = "raise",
-    ) -> NDFrameT:
+    ) -> Self:
         """
         Localize tz-naive index of a Series or DataFrame to target time zone.
 
@@ -10636,11 +10631,11 @@ def _tz_localize(ax, tz, ambiguous, nonexistent):
 
     @final
     def describe(
-        self: NDFrameT,
+        self,
         percentiles=None,
         include=None,
         exclude=None,
-    ) -> NDFrameT:
+    ) -> Self:
         """
         Generate descriptive statistics.
 
@@ -10885,13 +10880,13 @@ def describe(
 
     @final
     def pct_change(
-        self: NDFrameT,
+        self,
         periods: int = 1,
         fill_method: Literal["backfill", "bfill", "pad", "ffill"] | None = "pad",
         limit=None,
         freq=None,
         **kwargs,
-    ) -> NDFrameT:
+    ) -> Self:
         """
         Percentage change between the current and a prior element.
 
@@ -11015,7 +11010,7 @@ def pct_change(
             data = _data
 
         shifted = data.shift(periods=periods, freq=freq, axis=axis, **kwargs)
-        # Unsupported left operand type for / ("NDFrameT")
+        # Unsupported left operand type for / ("Self")
         rs = data / shifted - 1  # type: ignore[operator]
         if freq is not None:
             # Shift method is implemented differently when freq is not None
@@ -12028,47 +12023,47 @@ def _inplace_method(self, other, op):
         )
         return self
 
-    def __iadd__(self: NDFrameT, other) -> NDFrameT:
+    def __iadd__(self, other) -> Self:
         # error: Unsupported left operand type for + ("Type[NDFrame]")
         return self._inplace_method(other, type(self).__add__)  # type: ignore[operator]
 
-    def __isub__(self: NDFrameT, other) -> NDFrameT:
+    def __isub__(self, other) -> Self:
         # error: Unsupported left operand type for - ("Type[NDFrame]")
         return self._inplace_method(other, type(self).__sub__)  # type: ignore[operator]
 
-    def __imul__(self: NDFrameT, other) -> NDFrameT:
+    def __imul__(self, other) -> Self:
         # error: Unsupported left operand type for * ("Type[NDFrame]")
         return self._inplace_method(other, type(self).__mul__)  # type: ignore[operator]
 
-    def __itruediv__(self: NDFrameT, other) -> NDFrameT:
+    def __itruediv__(self, other) -> Self:
         # error: Unsupported left operand type for / ("Type[NDFrame]")
         return self._inplace_method(
             other, type(self).__truediv__  # type: ignore[operator]
         )
 
-    def __ifloordiv__(self: NDFrameT, other) -> NDFrameT:
+    def __ifloordiv__(self, other) -> Self:
         # error: Unsupported left operand type for // ("Type[NDFrame]")
         return self._inplace_method(
             other, type(self).__floordiv__  # type: ignore[operator]
         )
 
-    def __imod__(self: NDFrameT, other) -> NDFrameT:
+    def __imod__(self, other) -> Self:
         # error: Unsupported left operand type for % ("Type[NDFrame]")
         return self._inplace_method(other, type(self).__mod__)  # type: ignore[operator]
 
-    def __ipow__(self: NDFrameT, other) -> NDFrameT:
+    def __ipow__(self, other) -> Self:
         # error: Unsupported left operand type for ** ("Type[NDFrame]")
         return self._inplace_method(other, type(self).__pow__)  # type: ignore[operator]
 
-    def __iand__(self: NDFrameT, other) -> NDFrameT:
+    def __iand__(self, other) -> Self:
         # error: Unsupported left operand type for & ("Type[NDFrame]")
         return self._inplace_method(other, type(self).__and__)  # type: ignore[operator]
 
-    def __ior__(self: NDFrameT, other) -> NDFrameT:
+    def __ior__(self, other) -> Self:
         # error: Unsupported left operand type for | ("Type[NDFrame]")
         return self._inplace_method(other, type(self).__or__)  # type: ignore[operator]
 
-    def __ixor__(self: NDFrameT, other) -> NDFrameT:
+    def __ixor__(self, other) -> Self:
         # error: Unsupported left operand type for ^ ("Type[NDFrame]")
         return self._inplace_method(other, type(self).__xor__)  # type: ignore[operator]
 
diff --git a/pandas/core/indexes/base.py b/pandas/core/indexes/base.py
index 2f658006cf93f..177af1a95fcb0 100644
--- a/pandas/core/indexes/base.py
+++ b/pandas/core/indexes/base.py
@@ -14,7 +14,6 @@
     Literal,
     NoReturn,
     Sequence,
-    TypeVar,
     cast,
     final,
     overload,
@@ -55,6 +54,7 @@
     IndexLabel,
     JoinHow,
     Level,
+    Self,
     Shape,
     npt,
 )
@@ -293,9 +293,6 @@ def _new_Index(cls, d):
     return cls.__new__(cls, **d)
 
 
-_IndexT = TypeVar("_IndexT", bound="Index")
-
-
 class Index(IndexOpsMixin, PandasObject):
     """
     Immutable sequence used for indexing and alignment.
@@ -361,7 +358,7 @@ class Index(IndexOpsMixin, PandasObject):
     #  given the dtypes of the passed arguments
 
     @final
-    def _left_indexer_unique(self: _IndexT, other: _IndexT) -> npt.NDArray[np.intp]:
+    def _left_indexer_unique(self, other: Self) -> npt.NDArray[np.intp]:
         # Caller is responsible for ensuring other.dtype == self.dtype
         sv = self._get_join_target()
         ov = other._get_join_target()
@@ -373,7 +370,7 @@ def _left_indexer_unique(self: _IndexT, other: _IndexT) -> npt.NDArray[np.intp]:
 
     @final
     def _left_indexer(
-        self: _IndexT, other: _IndexT
+        self, other: Self
     ) -> tuple[ArrayLike, npt.NDArray[np.intp], npt.NDArray[np.intp]]:
         # Caller is responsible for ensuring other.dtype == self.dtype
         sv = self._get_join_target()
@@ -387,7 +384,7 @@ def _left_indexer(
 
     @final
     def _inner_indexer(
-        self: _IndexT, other: _IndexT
+        self, other: Self
     ) -> tuple[ArrayLike, npt.NDArray[np.intp], npt.NDArray[np.intp]]:
         # Caller is responsible for ensuring other.dtype == self.dtype
         sv = self._get_join_target()
@@ -401,7 +398,7 @@ def _inner_indexer(
 
     @final
     def _outer_indexer(
-        self: _IndexT, other: _IndexT
+        self, other: Self
     ) -> tuple[ArrayLike, npt.NDArray[np.intp], npt.NDArray[np.intp]]:
         # Caller is responsible for ensuring other.dtype == self.dtype
         sv = self._get_join_target()
@@ -632,9 +629,7 @@ def _dtype_to_subclass(cls, dtype: DtypeObj):
     # See each method's docstring.
 
     @classmethod
-    def _simple_new(
-        cls: type[_IndexT], values: ArrayLike, name: Hashable = None
-    ) -> _IndexT:
+    def _simple_new(cls, values: ArrayLike, name: Hashable = None) -> Self:
         """
         We require that we have a dtype compat for the values. If we are passed
         a non-dtype compat, then coerce using the constructor.
@@ -670,7 +665,7 @@ def _with_infer(cls, *args, **kwargs):
         return result
 
     @cache_readonly
-    def _constructor(self: _IndexT) -> type[_IndexT]:
+    def _constructor(self) -> type[Self]:
         return type(self)
 
     @final
@@ -729,7 +724,7 @@ def _format_duplicate_message(self) -> DataFrame:
     # --------------------------------------------------------------------
     # Index Internals Methods
 
-    def _shallow_copy(self: _IndexT, values, name: Hashable = no_default) -> _IndexT:
+    def _shallow_copy(self, values, name: Hashable = no_default) -> Self:
         """
         Create a new Index with the same class as the caller, don't copy the
         data, use the same object attributes with passed in attributes taking
@@ -746,7 +741,7 @@ def _shallow_copy(self: _IndexT, values, name: Hashable = no_default) -> _IndexT
 
         return self._simple_new(values, name=name)
 
-    def _view(self: _IndexT) -> _IndexT:
+    def _view(self) -> Self:
         """
         fastpath to make a shallow copy, i.e. new object with same data.
         """
@@ -756,7 +751,7 @@ def _view(self: _IndexT) -> _IndexT:
         return result
 
     @final
-    def _rename(self: _IndexT, name: Hashable) -> _IndexT:
+    def _rename(self, name: Hashable) -> Self:
         """
         fastpath for rename if new name is already validated.
         """
@@ -1154,10 +1149,10 @@ def repeat(self, repeats, axis=None):
     # Copying Methods
 
     def copy(
-        self: _IndexT,
+        self,
         name: Hashable | None = None,
         deep: bool = False,
-    ) -> _IndexT:
+    ) -> Self:
         """
         Make a copy of this object.
 
@@ -1189,11 +1184,11 @@ def copy(
         return new_index
 
     @final
-    def __copy__(self: _IndexT, **kwargs) -> _IndexT:
+    def __copy__(self, **kwargs) -> Self:
         return self.copy(**kwargs)
 
     @final
-    def __deepcopy__(self: _IndexT, memo=None) -> _IndexT:
+    def __deepcopy__(self, memo=None) -> Self:
         """
         Parameters
         ----------
@@ -1414,7 +1409,7 @@ def _summary(self, name=None) -> str_t:
     # --------------------------------------------------------------------
     # Conversion Methods
 
-    def to_flat_index(self: _IndexT) -> _IndexT:
+    def to_flat_index(self) -> Self:
         """
         Identity method.
 
@@ -1679,9 +1674,7 @@ def _set_names(self, values, *, level=None) -> None:
     names = property(fset=_set_names, fget=_get_names)
 
     @overload
-    def set_names(
-        self: _IndexT, names, *, level=..., inplace: Literal[False] = ...
-    ) -> _IndexT:
+    def set_names(self, names, *, level=..., inplace: Literal[False] = ...) -> Self:
         ...
 
     @overload
@@ -1689,14 +1682,10 @@ def set_names(self, names, *, level=..., inplace: Literal[True]) -> None:
         ...
 
     @overload
-    def set_names(
-        self: _IndexT, names, *, level=..., inplace: bool = ...
-    ) -> _IndexT | None:
+    def set_names(self, names, *, level=..., inplace: bool = ...) -> Self | None:
         ...
 
-    def set_names(
-        self: _IndexT, names, *, level=None, inplace: bool = False
-    ) -> _IndexT | None:
+    def set_names(self, names, *, level=None, inplace: bool = False) -> Self | None:
         """
         Set Index or MultiIndex name.
 
@@ -1862,7 +1851,7 @@ def nlevels(self) -> int:
         """
         return 1
 
-    def _sort_levels_monotonic(self: _IndexT) -> _IndexT:
+    def _sort_levels_monotonic(self) -> Self:
         """
         Compat with MultiIndex.
         """
@@ -2849,7 +2838,7 @@ def fillna(self, value=None, downcast=None):
             )
         return self._view()
 
-    def dropna(self: _IndexT, how: AnyAll = "any") -> _IndexT:
+    def dropna(self, how: AnyAll = "any") -> Self:
         """
         Return Index without NA/NaN values.
 
@@ -2874,7 +2863,7 @@ def dropna(self: _IndexT, how: AnyAll = "any") -> _IndexT:
     # --------------------------------------------------------------------
     # Uniqueness Methods
 
-    def unique(self: _IndexT, level: Hashable | None = None) -> _IndexT:
+    def unique(self, level: Hashable | None = None) -> Self:
         """
         Return unique values in the index.
 
@@ -2904,7 +2893,7 @@ def unique(self: _IndexT, level: Hashable | None = None) -> _IndexT:
         result = super().unique()
         return self._shallow_copy(result)
 
-    def drop_duplicates(self: _IndexT, *, keep: DropKeep = "first") -> _IndexT:
+    def drop_duplicates(self, *, keep: DropKeep = "first") -> Self:
         """
         Return Index with duplicate values removed.
 
@@ -4854,18 +4843,18 @@ def _join_monotonic(
         return join_index, lidx, ridx
 
     def _wrap_joined_index(
-        self: _IndexT,
+        self,
         joined: ArrayLike,
-        other: _IndexT,
+        other: Self,
         lidx: npt.NDArray[np.intp],
         ridx: npt.NDArray[np.intp],
-    ) -> _IndexT:
+    ) -> Self:
         assert other.dtype == self.dtype
 
         if isinstance(self, ABCMultiIndex):
             name = self.names if self.names == other.names else None
             # error: Incompatible return value type (got "MultiIndex",
-            # expected "_IndexT")
+            # expected "Self")
             mask = lidx == -1
             join_idx = self.take(lidx)
             right = other.take(ridx)
@@ -5189,7 +5178,7 @@ def __getitem__(self, key):
         #  didn't override __getitem__
         return self._constructor._simple_new(result, name=self._name)
 
-    def _getitem_slice(self: _IndexT, slobj: slice) -> _IndexT:
+    def _getitem_slice(self, slobj: slice) -> Self:
         """
         Fastpath for __getitem__ when we know we have a slice.
         """
@@ -6561,7 +6550,7 @@ def slice_locs(self, start=None, end=None, step=None) -> tuple[int, int]:
 
         return start_slice, end_slice
 
-    def delete(self: _IndexT, loc) -> _IndexT:
+    def delete(self, loc) -> Self:
         """
         Make new Index with passed location(-s) deleted.
 
diff --git a/pandas/core/indexes/datetimelike.py b/pandas/core/indexes/datetimelike.py
index 17fac22f578db..1133ea6be26ac 100644
--- a/pandas/core/indexes/datetimelike.py
+++ b/pandas/core/indexes/datetimelike.py
@@ -12,7 +12,6 @@
     Any,
     Callable,
     Sequence,
-    TypeVar,
     cast,
     final,
 )
@@ -69,6 +68,7 @@
 
     from pandas._typing import (
         Axis,
+        Self,
         npt,
     )
 
@@ -76,9 +76,6 @@
 
 _index_doc_kwargs = dict(ibase._index_doc_kwargs)
 
-_T = TypeVar("_T", bound="DatetimeIndexOpsMixin")
-_TDT = TypeVar("_TDT", bound="DatetimeTimedeltaMixin")
-
 
 class DatetimeIndexOpsMixin(NDArrayBackedExtensionIndex, ABC):
     """
@@ -358,7 +355,7 @@ def _maybe_cast_slice_bound(self, label, side: str):
     # --------------------------------------------------------------------
     # Arithmetic Methods
 
-    def shift(self: _T, periods: int = 1, freq=None) -> _T:
+    def shift(self, periods: int = 1, freq=None) -> Self:
         """
         Shift index by desired number of time frequency increments.
 
@@ -424,7 +421,7 @@ class DatetimeTimedeltaMixin(DatetimeIndexOpsMixin, ABC):
     def unit(self) -> str:
         return self._data.unit
 
-    def as_unit(self: _TDT, unit: str) -> _TDT:
+    def as_unit(self, unit: str) -> Self:
         """
         Convert to a dtype with the given unit resolution.
 
@@ -449,7 +446,7 @@ def values(self) -> np.ndarray:
         return self._data._ndarray
 
     @doc(DatetimeIndexOpsMixin.shift)
-    def shift(self: _TDT, periods: int = 1, freq=None) -> _TDT:
+    def shift(self, periods: int = 1, freq=None) -> Self:
         if freq is not None and freq != self.freq:
             if isinstance(freq, str):
                 freq = to_offset(freq)
@@ -569,7 +566,7 @@ def _fast_intersect(self, other, sort):
 
         return result
 
-    def _can_fast_intersect(self: _T, other: _T) -> bool:
+    def _can_fast_intersect(self, other: Self) -> bool:
         # Note: we only get here with len(self) > 0 and len(other) > 0
         if self.freq is None:
             return False
@@ -587,7 +584,7 @@ def _can_fast_intersect(self: _T, other: _T) -> bool:
         # GH#42104
         return self.freq.n == 1
 
-    def _can_fast_union(self: _T, other: _T) -> bool:
+    def _can_fast_union(self, other: Self) -> bool:
         # Assumes that type(self) == type(other), as per the annotation
         # The ability to fast_union also implies that `freq` should be
         #  retained on union.
@@ -617,7 +614,7 @@ def _can_fast_union(self: _T, other: _T) -> bool:
         # Only need to "adjoin", not overlap
         return (right_start == left_end + freq) or right_start in left
 
-    def _fast_union(self: _TDT, other: _TDT, sort=None) -> _TDT:
+    def _fast_union(self, other: Self, sort=None) -> Self:
         # Caller is responsible for ensuring self and other are non-empty
 
         # to make our life easier, "sort" the two ranges
diff --git a/pandas/core/indexes/extension.py b/pandas/core/indexes/extension.py
index 7d4dcf54a025f..61949531f37df 100644
--- a/pandas/core/indexes/extension.py
+++ b/pandas/core/indexes/extension.py
@@ -26,7 +26,6 @@
     from pandas.core.arrays import IntervalArray
     from pandas.core.arrays._mixins import NDArrayBackedExtensionArray
 
-_T = TypeVar("_T", bound="NDArrayBackedExtensionIndex")
 _ExtensionIndexT = TypeVar("_ExtensionIndexT", bound="ExtensionIndex")
 
 
diff --git a/pandas/core/series.py b/pandas/core/series.py
index 58cd42eaa7ca3..ac80a4a576bc7 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -173,6 +173,7 @@
         QuantileInterpolation,
         Renamer,
         Scalar,
+        Self,
         SingleManager,
         SortKind,
         StorageOptions,
@@ -4280,7 +4281,7 @@ def map(
             self, method="map"
         )
 
-    def _gotitem(self, key, ndim, subset=None) -> Series:
+    def _gotitem(self, key, ndim, subset=None) -> Self:
         """
         Sub-classes to define. Return a sliced object.
 
@@ -4597,7 +4598,7 @@ def align(
         limit: int | None = None,
         fill_axis: Axis = 0,
         broadcast_axis: Axis | None = None,
-    ) -> tuple[Series, NDFrameT]:
+    ) -> tuple[Self, NDFrameT]:
         return super().align(
             other,
             join=join,