allow cycles throught the __dict__ slot to be cleared (closes #1469629)

Patch from Armin, test from me.
This commit is contained in:
Benjamin Peterson 2012-03-07 18:41:11 -06:00
parent 1ae230aa1a
commit 52c424343d
3 changed files with 27 additions and 4 deletions

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@ -1,8 +1,10 @@
import builtins
import gc
import sys
import types
import math
import unittest
import weakref
from copy import deepcopy
from test import support
@ -1186,7 +1188,6 @@ order (MRO) for bases """
self.assertEqual(Counted.counter, 0)
# Test lookup leaks [SF bug 572567]
import gc
if hasattr(gc, 'get_objects'):
class G(object):
def __eq__(self, other):
@ -4380,7 +4381,6 @@ order (MRO) for bases """
self.assertRaises(AttributeError, getattr, C(), "attr")
self.assertEqual(descr.counter, 4)
import gc
class EvilGetattribute(object):
# This used to segfault
def __getattr__(self, name):
@ -4429,6 +4429,21 @@ order (MRO) for bases """
foo = Foo()
str(foo)
def test_cycle_through_dict(self):
# See bug #1469629
class X(dict):
def __init__(self):
dict.__init__(self)
self.__dict__ = self
x = X()
x.attr = 42
wr = weakref.ref(x)
del x
support.gc_collect()
self.assertIsNone(wr())
for o in gc.get_objects():
self.assertIsNot(type(o), X)
class DictProxyTests(unittest.TestCase):
def setUp(self):
class C(object):

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@ -10,6 +10,9 @@ What's New in Python 3.2.3 release candidate 1?
Core and Builtins
-----------------
- Issue #1469629: Allow cycles through an object's __dict__ slot to be
collected. (For example if ``x.__dict__ is x``).
- Issue #14172: Fix reference leak when marshalling a buffer-like object
(other than a bytes object).

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@ -830,8 +830,13 @@ subtype_clear(PyObject *self)
assert(base);
}
/* There's no need to clear the instance dict (if any);
the collector will call its tp_clear handler. */
/* Clear the instance dict (if any), to break cycles involving only
__dict__ slots (as in the case 'self.__dict__ is self'). */
if (type->tp_dictoffset != base->tp_dictoffset) {
PyObject **dictptr = _PyObject_GetDictPtr(self);
if (dictptr && *dictptr)
Py_CLEAR(*dictptr);
}
if (baseclear)
return baseclear(self);