CLN: callable to Series.iloc returning a tuple (#58626)

* CLN: callable to Series.iloc returning a tuple

* undo other change

* concat string

* Update doc/source/whatsnew/v3.0.0.rst

Co-authored-by: William Ayd <[email protected]>

---------

Co-authored-by: William Ayd <[email protected]>

Author: mroeschke

doc/source/whatsnew/v3.0.0.rst

@@ -223,6 +223,7 @@ Removal of prior version deprecations/changes
 - All arguments except ``name`` in :meth:`Index.rename` are now keyword only (:issue:`56493`)
 - All arguments except the first ``path``-like argument in IO writers are now keyword only (:issue:`54229`)
 - Changed behavior of :meth:`Series.__getitem__` and :meth:`Series.__setitem__` to always treat integer keys as labels, never as positional, consistent with :class:`DataFrame` behavior (:issue:`50617`)
+- Disallow a callable argument to :meth:`Series.iloc` to return a ``tuple`` (:issue:`53769`)
 - Disallow allowing logical operations (``||``, ``&``, ``^``) between pandas objects and dtype-less sequences (e.g. ``list``, ``tuple``); wrap the objects in :class:`Series`, :class:`Index`, or ``np.array`` first instead (:issue:`52264`)
 - Disallow automatic casting to object in :class:`Series` logical operations (``&``, ``^``, ``||``) between series with mismatched indexes and dtypes other than ``object`` or ``bool`` (:issue:`52538`)
 - Disallow calling :meth:`Series.replace` or :meth:`DataFrame.replace` without a ``value`` and with non-dict-like ``to_replace`` (:issue:`33302`)

pandas/core/indexing.py

@@ -159,7 +159,7 @@ def iloc(self) -> _iLocIndexer:
         """
         Purely integer-location based indexing for selection by position.
 
-        .. deprecated:: 2.2.0
+        .. versionchanged:: 3.0
 
            Returning a tuple from a callable is deprecated.
 
@@ -905,7 +905,7 @@ def __setitem__(self, key, value) -> None:
             key = tuple(com.apply_if_callable(x, self.obj) for x in key)
         else:
             maybe_callable = com.apply_if_callable(key, self.obj)
-            key = self._check_deprecated_callable_usage(key, maybe_callable)
+            key = self._raise_callable_usage(key, maybe_callable)
         indexer = self._get_setitem_indexer(key)
         self._has_valid_setitem_indexer(key)
 
@@ -1164,14 +1164,11 @@ def _contains_slice(x: object) -> bool:
     def _convert_to_indexer(self, key, axis: AxisInt):
         raise AbstractMethodError(self)
 
-    def _check_deprecated_callable_usage(self, key: Any, maybe_callable: T) -> T:
+    def _raise_callable_usage(self, key: Any, maybe_callable: T) -> T:
         # GH53533
         if self.name == "iloc" and callable(key) and isinstance(maybe_callable, tuple):
-            warnings.warn(
-                "Returning a tuple from a callable with iloc "
-                "is deprecated and will be removed in a future version",
-                FutureWarning,
-                stacklevel=find_stack_level(),
+            raise ValueError(
+                "Returning a tuple from a callable with iloc is not allowed.",
             )
         return maybe_callable
 
@@ -1189,7 +1186,7 @@ def __getitem__(self, key):
             axis = self.axis or 0
 
             maybe_callable = com.apply_if_callable(key, self.obj)
-            maybe_callable = self._check_deprecated_callable_usage(key, maybe_callable)
+            maybe_callable = self._raise_callable_usage(key, maybe_callable)
             return self._getitem_axis(maybe_callable, axis=axis)
 
     def _is_scalar_access(self, key: tuple):

pandas/tests/frame/indexing/test_indexing.py

@@ -1019,13 +1019,13 @@ def test_single_element_ix_dont_upcast(self, float_frame):
         result = df.loc[[0], "b"]
         tm.assert_series_equal(result, expected)
 
-    def test_iloc_callable_tuple_return_value(self):
-        # GH53769
+    def test_iloc_callable_tuple_return_value_raises(self):
+        # GH53769: Enforced pandas 3.0
         df = DataFrame(np.arange(40).reshape(10, 4), index=range(0, 20, 2))
-        msg = "callable with iloc"
-        with tm.assert_produces_warning(FutureWarning, match=msg):
+        msg = "Returning a tuple from"
+        with pytest.raises(ValueError, match=msg):
             df.iloc[lambda _: (0,)]
-        with tm.assert_produces_warning(FutureWarning, match=msg):
+        with pytest.raises(ValueError, match=msg):
             df.iloc[lambda _: (0,)] = 1
 
     def test_iloc_row(self):