tweak mro to get it working on python 3.14, fix refcount check for older python

Author: jorisvandenbossche

pandas/_libs/internals.pyx

@@ -1022,7 +1022,7 @@ cdef inline bint _is_unique_referenced_temporary(object obj) except -1:
     if PY_VERSION_HEX >= 0x030E0000:
         return PyUnstable_Object_IsUniqueReferencedTemporary(obj)
     else:
-        return sys.getrefcount(obj) == 2
+        return sys.getrefcount(obj) <= 1
 
 
 # # Python version compatibility for PyUnstable_Object_IsUniqueReferencedTemporary
@@ -1038,6 +1038,7 @@ cdef inline bint _is_unique_referenced_temporary(object obj) except -1:
 #         return sys.getrefcount(obj) == 2
 
 
+# @cython.auto_pickle(False)
 cdef class SetitemMixin:
 
     def __setitem__(self, key, value):
@@ -1052,3 +1053,6 @@ cdef class SetitemMixin:
                 stacklevel=1,
                 )
         self._setitem(key, value)
+
+    def __delitem__(self, key) -> None:
+        self._delitem(key)

pandas/core/frame.py

@@ -47,6 +47,7 @@
     properties,
 )
 from pandas._libs.hashtable import duplicated
+from pandas._libs.internals import SetitemMixin
 from pandas._libs.lib import is_range_indexer
 from pandas.compat import PYPY
 from pandas.compat._constants import REF_COUNT
@@ -510,7 +511,7 @@
 
 
 @set_module("pandas")
-class DataFrame(NDFrame, OpsMixin):
+class DataFrame(SetitemMixin, NDFrame, OpsMixin):
     """
     Two-dimensional, size-mutable, potentially heterogeneous tabular data.
 
@@ -659,6 +660,11 @@ class DataFrame(NDFrame, OpsMixin):
     #  and ExtensionArray.  Should NOT be overridden by subclasses.
     __pandas_priority__ = 4000
 
+    # override those to avoid inheriting from SetitemMixin (cython generates
+    # them by default)
+    __reduce__ = object.__reduce__
+    __setstate__ = NDFrame.__setstate__
+
     @property
     def _constructor(self) -> type[DataFrame]:
         return DataFrame

pandas/core/generic.py

@@ -27,7 +27,6 @@
 from pandas._config import config
 
 from pandas._libs import lib
-from pandas._libs.internals import SetitemMixin
 from pandas._libs.lib import is_range_indexer
 from pandas._libs.tslibs import (
     Period,
@@ -223,7 +222,7 @@
 }
 
 
-class NDFrame(PandasObject, indexing.IndexingMixin, SetitemMixin):
+class NDFrame(PandasObject, indexing.IndexingMixin):
     """
     N-dimensional analogue of DataFrame. Store multi-dimensional in a
     size-mutable, labeled data structure
@@ -253,11 +252,6 @@ class NDFrame(PandasObject, indexing.IndexingMixin, SetitemMixin):
     # ----------------------------------------------------------------------
     # Constructors
 
-    # override those to avoid inheriting from SetitemMixin (cython generates
-    # them by default)
-    __new__ = object.__new__
-    __reduce__ = object.__reduce__
-
     def __init__(self, data: Manager) -> None:
         object.__setattr__(self, "_mgr", data)
         object.__setattr__(self, "_attrs", {})
@@ -4263,8 +4257,9 @@ def _slice(self, slobj: slice, axis: AxisInt = 0) -> Self:
         result = result.__finalize__(self)
         return result
 
+    # __delitem__ is implemented in SetitemMixin and dispatches to this method
     @final
-    def __delitem__(self, key) -> None:
+    def _delitem(self, key) -> None:
         """
         Delete item
         """

pandas/core/series.py

@@ -32,6 +32,7 @@
     properties,
     reshape,
 )
+from pandas._libs.internals import SetitemMixin
 from pandas._libs.lib import is_range_indexer
 from pandas.compat import PYPY
 from pandas.compat._constants import REF_COUNT
@@ -233,7 +234,7 @@
 # class "NDFrame")
 # definition in base class "NDFrame"
 @set_module("pandas")
-class Series(base.IndexOpsMixin, NDFrame):  # type: ignore[misc]
+class Series(SetitemMixin, base.IndexOpsMixin, NDFrame):  # type: ignore[misc]
     """
     One-dimensional ndarray with axis labels (including time series).
 
@@ -361,6 +362,11 @@ class Series(base.IndexOpsMixin, NDFrame):  # type: ignore[misc]
     )
     _mgr: SingleBlockManager
 
+    # override those to avoid inheriting from SetitemMixin (cython generates
+    # them by default)
+    __reduce__ = object.__reduce__
+    __setstate__ = NDFrame.__setstate__
+
     # ----------------------------------------------------------------------
     # Constructors