DEPR: ExtensionOpsMixin -> OpsMixin (#38142)

Author: jbrockmendel

doc/source/whatsnew/v1.2.0.rst

@@ -492,6 +492,7 @@ Deprecations
 - Deprecated :meth:`Index.asi8` for :class:`Index` subclasses other than :class:`.DatetimeIndex`, :class:`.TimedeltaIndex`, and :class:`PeriodIndex` (:issue:`37877`)
 - The ``inplace`` parameter of :meth:`Categorical.remove_unused_categories` is deprecated and will be removed in a future version (:issue:`37643`)
 - The ``null_counts`` parameter of :meth:`DataFrame.info` is deprecated and replaced by ``show_counts``. It will be removed in a future version (:issue:`37999`)
+- :class:`ExtensionOpsMixin` and :class:`ExtensionScalarOpsMixin` are deprecated and will be removed in a future version.  Use ``pd.core.arraylike.OpsMixin`` instead (:issue:`37080`)
 
 .. ---------------------------------------------------------------------------
 

pandas/core/arrays/base.py

@@ -21,6 +21,7 @@
     Union,
     cast,
 )
+import warnings
 
 import numpy as np
 
@@ -1237,6 +1238,21 @@ class ExtensionOpsMixin:
        with NumPy arrays.
     """
 
+    def __init_subclass__(cls, **kwargs):
+        # We use __init_subclass__ to handle deprecations
+        super().__init_subclass__()
+
+        if cls.__name__ != "ExtensionScalarOpsMixin":
+            # We only want to warn for user-defined subclasses,
+            #  and cannot reference ExtensionScalarOpsMixin directly at this point.
+            warnings.warn(
+                "ExtensionOpsMixin and ExtensionScalarOpsMixin are deprecated "
+                "and will be removed in a future version. Use "
+                "pd.core.arraylike.OpsMixin instead.",
+                FutureWarning,
+                stacklevel=2,
+            )
+
     @classmethod
     def _create_arithmetic_method(cls, op):
         raise AbstractMethodError(cls)

pandas/tests/arrays/test_deprecations.py

@@ -0,0 +1,19 @@
+import pandas._testing as tm
+from pandas.core.arrays import (
+    ExtensionArray,
+    ExtensionOpsMixin,
+    ExtensionScalarOpsMixin,
+)
+
+
+def test_extension_ops_mixin_deprecated():
+    # GH#37080 deprecated in favor of OpsMixin
+    with tm.assert_produces_warning(FutureWarning):
+
+        class MySubclass(ExtensionOpsMixin, ExtensionArray):
+            pass
+
+    with tm.assert_produces_warning(FutureWarning):
+
+        class MyOtherSubclass(ExtensionScalarOpsMixin, ExtensionArray):
+            pass

pandas/tests/extension/decimal/array.py

@@ -7,12 +7,13 @@
 import numpy as np
 
 from pandas.core.dtypes.base import ExtensionDtype
+from pandas.core.dtypes.cast import maybe_cast_to_extension_array
 from pandas.core.dtypes.common import is_dtype_equal, is_list_like, pandas_dtype
 
 import pandas as pd
 from pandas.api.extensions import no_default, register_extension_dtype
 from pandas.core.arraylike import OpsMixin
-from pandas.core.arrays import ExtensionArray, ExtensionScalarOpsMixin
+from pandas.core.arrays import ExtensionArray
 from pandas.core.indexers import check_array_indexer
 
 
@@ -45,7 +46,7 @@ def _is_numeric(self) -> bool:
         return True
 
 
-class DecimalArray(OpsMixin, ExtensionScalarOpsMixin, ExtensionArray):
+class DecimalArray(OpsMixin, ExtensionArray):
     __array_priority__ = 1000
 
     def __init__(self, values, dtype=None, copy=False, context=None):
@@ -225,13 +226,46 @@ def convert_values(param):
 
         return np.asarray(res, dtype=bool)
 
+    _do_coerce = True  # overriden in DecimalArrayWithoutCoercion
+
+    def _arith_method(self, other, op):
+        def convert_values(param):
+            if isinstance(param, ExtensionArray) or is_list_like(param):
+                ovalues = param
+            else:  # Assume its an object
+                ovalues = [param] * len(self)
+            return ovalues
+
+        lvalues = self
+        rvalues = convert_values(other)
+
+        # If the operator is not defined for the underlying objects,
+        # a TypeError should be raised
+        res = [op(a, b) for (a, b) in zip(lvalues, rvalues)]
+
+        def _maybe_convert(arr):
+            if self._do_coerce:
+                # https://github.com/pandas-dev/pandas/issues/22850
+                # We catch all regular exceptions here, and fall back
+                # to an ndarray.
+                res = maybe_cast_to_extension_array(type(self), arr)
+                if not isinstance(res, type(self)):
+                    # exception raised in _from_sequence; ensure we have ndarray
+                    res = np.asarray(arr)
+            else:
+                res = np.asarray(arr)
+            return res
+
+        if op.__name__ in {"divmod", "rdivmod"}:
+            a, b = zip(*res)
+            return _maybe_convert(a), _maybe_convert(b)
+
+        return _maybe_convert(res)
+
 
 def to_decimal(values, context=None):
     return DecimalArray([decimal.Decimal(x) for x in values], context=context)
 
 
 def make_data():
     return [decimal.Decimal(random.random()) for _ in range(100)]
-
-
-DecimalArray._add_arithmetic_ops()

pandas/tests/extension/decimal/test_decimal.py

@@ -335,12 +335,7 @@ def _from_sequence(cls, scalars, dtype=None, copy=False):
 
 
 class DecimalArrayWithoutCoercion(DecimalArrayWithoutFromSequence):
-    @classmethod
-    def _create_arithmetic_method(cls, op):
-        return cls._create_method(op, coerce_to_dtype=False)
-
-
-DecimalArrayWithoutCoercion._add_arithmetic_ops()
+    _do_coerce = False
 
 
 def test_combine_from_sequence_raises():