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gh-144330: Initialize staticmethod/classmethod callables in tp_new #144440

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gh-144330: Initialize staticmethod/classmethod callables in tp_new #144440

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7b72250
Initialize staticmethod/classmethod callables in tp_new
Aniketsy Feb 3, 2026
80f9c47
Initialize staticmethod/classmethod callables in tp_new
Aniketsy Feb 3, 2026
ee324fe
Initialize staticmethod/classmethod callables in tp_new
Aniketsy Feb 3, 2026
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18 changes: 18 additions & 0 deletions Lib/test/test_descr.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1832,6 +1832,24 @@ def test_staticmethods_in_c(self):
self.assertEqual(a, a1)
self.assertEqual(d, d1)

def test_staticmethod_new(self):
sm = staticmethod.__new__(staticmethod, None)
self.assertEqual(repr(sm), '<staticmethod(None)>')

def test_classmethod_new(self):
cm = classmethod.__new__(classmethod, None)
self.assertEqual(repr(cm), '<classmethod(None)>')

def test_staticmethod_func_readonly(self):
sm = staticmethod(lambda x: x)
with self.assertRaises(AttributeError):
sm.__func__ = None

def test_classmethod_func_readonly(self):
cm = classmethod(lambda x: x)
with self.assertRaises(AttributeError):
cm.__func__ = None

def test_classic(self):
# Testing classic classes...
class C:
Expand Down
34 changes: 30 additions & 4 deletions Objects/funcobject.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1555,11 +1555,24 @@ static PyMethodDef cm_methodlist[] = {
{NULL} /* Sentinel */
};

static PyObject *
cm_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
classmethod *cm = (classmethod *)PyType_GenericAlloc(type, 0);
if (cm == NULL) {
return NULL;
}
cm->cm_callable = Py_None;
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@vstinner vstinner Feb 4, 2026

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With this change, cm->cm_callable cannot be NULL anymore:

  • cm_repr(): So you can remove cm->cm_callable != NULL (revert your change).
  • cm_dealloc(): Py_XDECREF(cm->cm_callable); can be replaced with Py_DECREF(cm->cm_callable);.
  • cm_descr_get(): I suggest to replace if (cm->cm_callable == NULL) with if (cm->cm_callable == Py_None).
  • cm_init(): replace Py_XSETREF(cm->cm_callable, ...) with Py_SETREF(cm->cm_callable, ...).

cm->cm_dict = NULL;
return (PyObject *)cm;
}

static PyObject*
cm_repr(PyObject *self)
{
classmethod *cm = _PyClassMethod_CAST(self);
return PyUnicode_FromFormat("<classmethod(%R)>", cm->cm_callable);
PyObject *callable = cm->cm_callable != NULL ? cm->cm_callable : Py_None;
return PyUnicode_FromFormat("<classmethod(%R)>", callable);
}

PyDoc_STRVAR(classmethod_doc,
Expand Down Expand Up @@ -1623,7 +1636,7 @@ PyTypeObject PyClassMethod_Type = {
offsetof(classmethod, cm_dict), /* tp_dictoffset */
cm_init, /* tp_init */
PyType_GenericAlloc, /* tp_alloc */
PyType_GenericNew, /* tp_new */
cm_new, /* tp_new */
PyObject_GC_Del, /* tp_free */
};

Expand Down Expand Up @@ -1796,7 +1809,20 @@ static PyObject*
sm_repr(PyObject *self)
{
staticmethod *sm = _PyStaticMethod_CAST(self);
return PyUnicode_FromFormat("<staticmethod(%R)>", sm->sm_callable);
PyObject *callable = sm->sm_callable != NULL ? sm->sm_callable : Py_None;
return PyUnicode_FromFormat("<staticmethod(%R)>", callable);
}

static PyObject *
sm_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
staticmethod *sm = (staticmethod *)PyType_GenericAlloc(type, 0);
if (sm == NULL) {
return NULL;
}
sm->sm_callable = Py_None;
sm->sm_dict = NULL;
return (PyObject *)sm;
}

PyDoc_STRVAR(staticmethod_doc,
Expand Down Expand Up @@ -1858,7 +1884,7 @@ PyTypeObject PyStaticMethod_Type = {
offsetof(staticmethod, sm_dict), /* tp_dictoffset */
sm_init, /* tp_init */
PyType_GenericAlloc, /* tp_alloc */
PyType_GenericNew, /* tp_new */
sm_new, /* tp_new */
PyObject_GC_Del, /* tp_free */
};

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