https://github.com/python/cpython/commit/86ec8aa7ed2275a3a6e123d536812dd75e657d1b commit: 86ec8aa7ed2275a3a6e123d536812dd75e657d1b branch: 3.13 author: Miss Islington (bot) <[email protected]> committer: encukou <[email protected]> date: 2024-10-28T13:49:45+01:00 summary:
[3.13] gh-125783: Add tests to prevent regressions with the combination of `ctypes` and metaclasses. (GH-125881) (#125987) gh-125783: Add tests to prevent regressions with the combination of `ctypes` and metaclasses. (GH-125881) (cherry picked from commit 13844094609cf8265a2eed023e33c7002f3f530d) Co-authored-by: Jun Komoda <[email protected]> files: A Lib/test/test_ctypes/test_c_simple_type_meta.py diff --git a/Lib/test/test_ctypes/test_c_simple_type_meta.py b/Lib/test/test_ctypes/test_c_simple_type_meta.py new file mode 100644 index 00000000000000..fa5144a3ca01bb --- /dev/null +++ b/Lib/test/test_ctypes/test_c_simple_type_meta.py @@ -0,0 +1,87 @@ +import unittest +import ctypes +from ctypes import POINTER, c_void_p + +from ._support import PyCSimpleType + + +class PyCSimpleTypeAsMetaclassTest(unittest.TestCase): + def tearDown(self): + # to not leak references, we must clean _pointer_type_cache + ctypes._reset_cache() + + def test_creating_pointer_in_dunder_new_1(self): + # Test metaclass whose instances are C types; when the type is + # created it automatically creates a pointer type for itself. + # The pointer type is also an instance of the metaclass. + # Such an implementation is used in `IUnknown` of the `comtypes` + # project. See gh-124520. + + class ct_meta(type): + def __new__(cls, name, bases, namespace): + self = super().__new__(cls, name, bases, namespace) + + # Avoid recursion: don't set up a pointer to + # a pointer (to a pointer...) + if bases == (c_void_p,): + # When creating PtrBase itself, the name + # is not yet available + return self + if issubclass(self, PtrBase): + return self + + if bases == (object,): + ptr_bases = (self, PtrBase) + else: + ptr_bases = (self, POINTER(bases[0])) + p = p_meta(f"POINTER({self.__name__})", ptr_bases, {}) + ctypes._pointer_type_cache[self] = p + return self + + class p_meta(PyCSimpleType, ct_meta): + pass + + class PtrBase(c_void_p, metaclass=p_meta): + pass + + class CtBase(object, metaclass=ct_meta): + pass + + class Sub(CtBase): + pass + + class Sub2(Sub): + pass + + self.assertIsInstance(POINTER(Sub2), p_meta) + self.assertTrue(issubclass(POINTER(Sub2), Sub2)) + self.assertTrue(issubclass(POINTER(Sub2), POINTER(Sub))) + self.assertTrue(issubclass(POINTER(Sub), POINTER(CtBase))) + + def test_creating_pointer_in_dunder_new_2(self): + # A simpler variant of the above, used in `CoClass` of the `comtypes` + # project. + + class ct_meta(type): + def __new__(cls, name, bases, namespace): + self = super().__new__(cls, name, bases, namespace) + if isinstance(self, p_meta): + return self + p = p_meta(f"POINTER({self.__name__})", (self, c_void_p), {}) + ctypes._pointer_type_cache[self] = p + return self + + class p_meta(PyCSimpleType, ct_meta): + pass + + class Core(object): + pass + + class CtBase(Core, metaclass=ct_meta): + pass + + class Sub(CtBase): + pass + + self.assertIsInstance(POINTER(Sub), p_meta) + self.assertTrue(issubclass(POINTER(Sub), Sub)) _______________________________________________ Python-checkins mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3/lists/python-checkins.python.org/ Member address: [email protected]
