gh-121654: Add PyType_Freeze() function (#122457) · python/cpython@db96327 · GitHub
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gh-121654: Add PyType_Freeze() function (#122457)
Co-authored-by: Petr Viktorin <encukou@gmail.com>
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‎Doc/c-api/type.rst‎

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‎Doc/data/stable_abi.dat‎

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‎Doc/whatsnew/3.14.rst‎

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@@ -777,6 +777,9 @@ New features
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(Contributed by Victor Stinner in :gh:`124502`.)
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* Add :c:func:`PyType_Freeze` function to make a type immutable.
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(Contributed by Victor Stinner in :gh:`121654`.)
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Porting to Python 3.14
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----------------------
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‎Include/object.h‎

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@@ -796,6 +796,10 @@ static inline int PyType_CheckExact(PyObject *op) {
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PyAPI_FUNC(PyObject *) PyType_GetModuleByDef(PyTypeObject *, PyModuleDef *);
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#endif
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#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x030e0000
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PyAPI_FUNC(int) PyType_Freeze(PyTypeObject *type);
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#endif
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#ifdef __cplusplus
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}
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#endif

‎Lib/test/test_capi/test_type.py‎

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from test.support import import_helper
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import unittest
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_testcapi = import_helper.import_module('_testcapi')
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class TypeTests(unittest.TestCase):
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def test_freeze(self):
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# test PyType_Freeze()
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type_freeze = _testcapi.type_freeze
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# simple case, no inherante
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class MyType:
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pass
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MyType.attr = "mutable"
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type_freeze(MyType)
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err_msg = "cannot set 'attr' attribute of immutable type 'MyType'"
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with self.assertRaisesRegex(TypeError, err_msg):
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# the class is now immutable
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MyType.attr = "immutable"
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# test MRO: PyType_Freeze() requires base classes to be immutable
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class A: pass
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class B: pass
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class C(B): pass
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class D(A, C): pass
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self.assertEqual(D.mro(), [D, A, C, B, object])
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with self.assertRaises(TypeError):
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type_freeze(D)
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type_freeze(A)
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type_freeze(B)
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type_freeze(C)
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# all parent classes are now immutable, so D can be made immutable
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# as well
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type_freeze(D)
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def test_freeze_meta(self):
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"""test PyType_Freeze() with overridden MRO"""
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type_freeze = _testcapi.type_freeze
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class Base:
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value = 1
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class Meta(type):
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def mro(cls):
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return (cls, Base, object)
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class FreezeThis(metaclass=Meta):
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"""This has `Base` in the MRO, but not tp_bases"""
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self.assertEqual(FreezeThis.value, 1)
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with self.assertRaises(TypeError):
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type_freeze(FreezeThis)
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Base.value = 2
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self.assertEqual(FreezeThis.value, 2)
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type_freeze(Base)
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with self.assertRaises(TypeError):
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Base.value = 3
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type_freeze(FreezeThis)
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self.assertEqual(FreezeThis.value, 2)

‎Lib/test/test_stable_abi_ctypes.py‎

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‎Misc/NEWS.d/next/C_API/2024-07-30-14-40-08.gh-issue-121654.tgGeAl.rst‎

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Add :c:func:`PyType_Freeze` function to make a type immutable. Patch by
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Victor Stinner.

‎Misc/stable_abi.toml‎

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added = '3.14'
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[function.PyUnicode_Equal]
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added = '3.14'
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[function.PyType_Freeze]
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added = '3.14'

‎Modules/_testcapimodule.c‎

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@@ -3310,6 +3310,7 @@ test_critical_sections(PyObject *module, PyObject *Py_UNUSED(args))
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Py_RETURN_NONE;
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}
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// Used by `finalize_thread_hang`.
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#ifdef _POSIX_THREADS
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static void finalize_thread_hang_cleanup_callback(void *Py_UNUSED(arg)) {
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}
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static PyObject *
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type_freeze(PyObject *module, PyObject *args)
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{
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PyTypeObject *type;
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if (!PyArg_ParseTuple(args, "O!", &PyType_Type, &type)) {
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return NULL;
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}
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if (PyType_Freeze(type) < 0) {
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return NULL;
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}
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Py_RETURN_NONE;
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}
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static PyMethodDef TestMethods[] = {
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{"set_errno", set_errno, METH_VARARGS},
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{"test_config", test_config, METH_NOARGS},
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{"function_set_warning", function_set_warning, METH_NOARGS},
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{"test_critical_sections", test_critical_sections, METH_NOARGS},
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{"finalize_thread_hang", finalize_thread_hang, METH_O, NULL},
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{"type_freeze", type_freeze, METH_VARARGS},
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{NULL, NULL} /* sentinel */
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};
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‎Objects/typeobject.c‎

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