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cpython/Lib/test/test_weakref.py

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import gc
import sys
import unittest
import collections
import weakref
import operator
import contextlib
import copy
from test import support, script_helper
# Used in ReferencesTestCase.test_ref_created_during_del() .
ref_from_del = None
# Used by FinalizeTestCase as a global that may be replaced by None
# when the interpreter shuts down.
_global_var = 'foobar'
class C:
def method(self):
pass
class Callable:
bar = None
def __call__(self, x):
self.bar = x
def create_function():
def f(): pass
return f
def create_bound_method():
return C().method
class Object:
def __init__(self, arg):
self.arg = arg
def __repr__(self):
return "<Object %r>" % self.arg
def __eq__(self, other):
if isinstance(other, Object):
return self.arg == other.arg
return NotImplemented
def __lt__(self, other):
if isinstance(other, Object):
return self.arg < other.arg
return NotImplemented
def __hash__(self):
return hash(self.arg)
def some_method(self):
return 4
def other_method(self):
return 5
class RefCycle:
def __init__(self):
self.cycle = self
class TestBase(unittest.TestCase):
def setUp(self):
self.cbcalled = 0
def callback(self, ref):
self.cbcalled += 1
class ReferencesTestCase(TestBase):
def test_basic_ref(self):
self.check_basic_ref(C)
self.check_basic_ref(create_function)
self.check_basic_ref(create_bound_method)
# Just make sure the tp_repr handler doesn't raise an exception.
# Live reference:
o = C()
wr = weakref.ref(o)
repr(wr)
# Dead reference:
del o
repr(wr)
def test_basic_callback(self):
self.check_basic_callback(C)
self.check_basic_callback(create_function)
self.check_basic_callback(create_bound_method)
def test_multiple_callbacks(self):
o = C()
ref1 = weakref.ref(o, self.callback)
ref2 = weakref.ref(o, self.callback)
del o
self.assertTrue(ref1() is None,
"expected reference to be invalidated")
self.assertTrue(ref2() is None,
"expected reference to be invalidated")
self.assertTrue(self.cbcalled == 2,
"callback not called the right number of times")
def test_multiple_selfref_callbacks(self):
# Make sure all references are invalidated before callbacks are called
#
# What's important here is that we're using the first
# reference in the callback invoked on the second reference
# (the most recently created ref is cleaned up first). This
# tests that all references to the object are invalidated
# before any of the callbacks are invoked, so that we only
# have one invocation of _weakref.c:cleanup_helper() active
# for a particular object at a time.
#
def callback(object, self=self):
self.ref()
c = C()
self.ref = weakref.ref(c, callback)
ref1 = weakref.ref(c, callback)
del c
def test_proxy_ref(self):
o = C()
o.bar = 1
ref1 = weakref.proxy(o, self.callback)
ref2 = weakref.proxy(o, self.callback)
del o
def check(proxy):
proxy.bar
self.assertRaises(ReferenceError, check, ref1)
self.assertRaises(ReferenceError, check, ref2)
self.assertRaises(ReferenceError, bool, weakref.proxy(C()))
self.assertEqual(self.cbcalled, 2)
def check_basic_ref(self, factory):
o = factory()
ref = weakref.ref(o)
self.assertTrue(ref() is not None,
"weak reference to live object should be live")
o2 = ref()
self.assertTrue(o is o2,
"<ref>() should return original object if live")
def check_basic_callback(self, factory):
self.cbcalled = 0
o = factory()
ref = weakref.ref(o, self.callback)
del o
self.assertTrue(self.cbcalled == 1,
"callback did not properly set 'cbcalled'")
self.assertTrue(ref() is None,
"ref2 should be dead after deleting object reference")
def test_ref_reuse(self):
o = C()
ref1 = weakref.ref(o)
# create a proxy to make sure that there's an intervening creation
# between these two; it should make no difference
proxy = weakref.proxy(o)
ref2 = weakref.ref(o)
self.assertTrue(ref1 is ref2,
"reference object w/out callback should be re-used")
o = C()
proxy = weakref.proxy(o)
ref1 = weakref.ref(o)
ref2 = weakref.ref(o)
self.assertTrue(ref1 is ref2,
"reference object w/out callback should be re-used")
self.assertTrue(weakref.getweakrefcount(o) == 2,
"wrong weak ref count for object")
del proxy
self.assertTrue(weakref.getweakrefcount(o) == 1,
"wrong weak ref count for object after deleting proxy")
def test_proxy_reuse(self):
o = C()
proxy1 = weakref.proxy(o)
ref = weakref.ref(o)
proxy2 = weakref.proxy(o)
self.assertTrue(proxy1 is proxy2,
"proxy object w/out callback should have been re-used")
def test_basic_proxy(self):
o = C()
self.check_proxy(o, weakref.proxy(o))
L = collections.UserList()
p = weakref.proxy(L)
self.assertFalse(p, "proxy for empty UserList should be false")
p.append(12)
self.assertEqual(len(L), 1)
self.assertTrue(p, "proxy for non-empty UserList should be true")
p[:] = [2, 3]
self.assertEqual(len(L), 2)
self.assertEqual(len(p), 2)
self.assertIn(3, p, "proxy didn't support __contains__() properly")
p[1] = 5
self.assertEqual(L[1], 5)
self.assertEqual(p[1], 5)
L2 = collections.UserList(L)
p2 = weakref.proxy(L2)
self.assertEqual(p, p2)
## self.assertEqual(repr(L2), repr(p2))
L3 = collections.UserList(range(10))
p3 = weakref.proxy(L3)
self.assertEqual(L3[:], p3[:])
self.assertEqual(L3[5:], p3[5:])
self.assertEqual(L3[:5], p3[:5])
self.assertEqual(L3[2:5], p3[2:5])
def test_proxy_unicode(self):
# See bug 5037
class C(object):
def __str__(self):
return "string"
def __bytes__(self):
return b"bytes"
instance = C()
self.assertIn("__bytes__", dir(weakref.proxy(instance)))
self.assertEqual(bytes(weakref.proxy(instance)), b"bytes")
def test_proxy_index(self):
class C:
def __index__(self):
return 10
o = C()
p = weakref.proxy(o)
self.assertEqual(operator.index(p), 10)
def test_proxy_div(self):
class C:
def __floordiv__(self, other):
return 42
def __ifloordiv__(self, other):
return 21
o = C()
p = weakref.proxy(o)
self.assertEqual(p // 5, 42)
p //= 5
self.assertEqual(p, 21)
# The PyWeakref_* C API is documented as allowing either NULL or
# None as the value for the callback, where either means "no
# callback". The "no callback" ref and proxy objects are supposed
# to be shared so long as they exist by all callers so long as
# they are active. In Python 2.3.3 and earlier, this guarantee
# was not honored, and was broken in different ways for
# PyWeakref_NewRef() and PyWeakref_NewProxy(). (Two tests.)
def test_shared_ref_without_callback(self):
self.check_shared_without_callback(weakref.ref)
def test_shared_proxy_without_callback(self):
self.check_shared_without_callback(weakref.proxy)
def check_shared_without_callback(self, makeref):
o = Object(1)
p1 = makeref(o, None)
p2 = makeref(o, None)
self.assertTrue(p1 is p2, "both callbacks were None in the C API")
del p1, p2
p1 = makeref(o)
p2 = makeref(o, None)
self.assertTrue(p1 is p2, "callbacks were NULL, None in the C API")
del p1, p2
p1 = makeref(o)
p2 = makeref(o)
self.assertTrue(p1 is p2, "both callbacks were NULL in the C API")
del p1, p2
p1 = makeref(o, None)
p2 = makeref(o)
self.assertTrue(p1 is p2, "callbacks were None, NULL in the C API")
def test_callable_proxy(self):
o = Callable()
ref1 = weakref.proxy(o)
self.check_proxy(o, ref1)
self.assertTrue(type(ref1) is weakref.CallableProxyType,
"proxy is not of callable type")
ref1('twinkies!')
self.assertTrue(o.bar == 'twinkies!',
"call through proxy not passed through to original")
ref1(x='Splat.')
self.assertTrue(o.bar == 'Splat.',
"call through proxy not passed through to original")
# expect due to too few args
self.assertRaises(TypeError, ref1)
# expect due to too many args
self.assertRaises(TypeError, ref1, 1, 2, 3)
def check_proxy(self, o, proxy):
o.foo = 1
self.assertTrue(proxy.foo == 1,
"proxy does not reflect attribute addition")
o.foo = 2
self.assertTrue(proxy.foo == 2,
"proxy does not reflect attribute modification")
del o.foo
self.assertTrue(not hasattr(proxy, 'foo'),
"proxy does not reflect attribute removal")
proxy.foo = 1
self.assertTrue(o.foo == 1,
"object does not reflect attribute addition via proxy")
proxy.foo = 2
self.assertTrue(
o.foo == 2,
"object does not reflect attribute modification via proxy")
del proxy.foo
self.assertTrue(not hasattr(o, 'foo'),
"object does not reflect attribute removal via proxy")
def test_proxy_deletion(self):
# Test clearing of SF bug #762891
class Foo:
result = None
def __delitem__(self, accessor):
self.result = accessor
g = Foo()
f = weakref.proxy(g)
del f[0]
self.assertEqual(f.result, 0)
def test_proxy_bool(self):
# Test clearing of SF bug #1170766
class List(list): pass
lyst = List()
self.assertEqual(bool(weakref.proxy(lyst)), bool(lyst))
def test_getweakrefcount(self):
o = C()
ref1 = weakref.ref(o)
ref2 = weakref.ref(o, self.callback)
self.assertTrue(weakref.getweakrefcount(o) == 2,
"got wrong number of weak reference objects")
proxy1 = weakref.proxy(o)
proxy2 = weakref.proxy(o, self.callback)
self.assertTrue(weakref.getweakrefcount(o) == 4,
"got wrong number of weak reference objects")
del ref1, ref2, proxy1, proxy2
self.assertTrue(weakref.getweakrefcount(o) == 0,
"weak reference objects not unlinked from"
" referent when discarded.")
# assumes ints do not support weakrefs
self.assertTrue(weakref.getweakrefcount(1) == 0,
"got wrong number of weak reference objects for int")
def test_getweakrefs(self):
o = C()
ref1 = weakref.ref(o, self.callback)
ref2 = weakref.ref(o, self.callback)
del ref1
self.assertTrue(weakref.getweakrefs(o) == [ref2],
"list of refs does not match")
o = C()
ref1 = weakref.ref(o, self.callback)
ref2 = weakref.ref(o, self.callback)
del ref2
self.assertTrue(weakref.getweakrefs(o) == [ref1],
"list of refs does not match")
del ref1
self.assertTrue(weakref.getweakrefs(o) == [],
"list of refs not cleared")
# assumes ints do not support weakrefs
self.assertTrue(weakref.getweakrefs(1) == [],
"list of refs does not match for int")
def test_newstyle_number_ops(self):
class F(float):
pass
f = F(2.0)
p = weakref.proxy(f)
self.assertTrue(p + 1.0 == 3.0)
self.assertTrue(1.0 + p == 3.0) # this used to SEGV
def test_callbacks_protected(self):
# Callbacks protected from already-set exceptions?
# Regression test for SF bug #478534.
class BogusError(Exception):
pass
data = {}
def remove(k):
del data[k]
def encapsulate():
f = lambda : ()
data[weakref.ref(f, remove)] = None
raise BogusError
try:
encapsulate()
except BogusError:
pass
else:
self.fail("exception not properly restored")
try:
encapsulate()
except BogusError:
pass
else:
self.fail("exception not properly restored")
def test_sf_bug_840829(self):
# "weakref callbacks and gc corrupt memory"
# subtype_dealloc erroneously exposed a new-style instance
# already in the process of getting deallocated to gc,
# causing double-deallocation if the instance had a weakref
# callback that triggered gc.
# If the bug exists, there probably won't be an obvious symptom
# in a release build. In a debug build, a segfault will occur
# when the second attempt to remove the instance from the "list
# of all objects" occurs.
import gc
class C(object):
pass
c = C()
wr = weakref.ref(c, lambda ignore: gc.collect())
del c
# There endeth the first part. It gets worse.
del wr
c1 = C()
c1.i = C()
wr = weakref.ref(c1.i, lambda ignore: gc.collect())
c2 = C()
c2.c1 = c1
del c1 # still alive because c2 points to it
# Now when subtype_dealloc gets called on c2, it's not enough just
# that c2 is immune from gc while the weakref callbacks associated
# with c2 execute (there are none in this 2nd half of the test, btw).
# subtype_dealloc goes on to call the base classes' deallocs too,
# so any gc triggered by weakref callbacks associated with anything
# torn down by a base class dealloc can also trigger double
# deallocation of c2.
del c2
def test_callback_in_cycle_1(self):
import gc
class J(object):
pass
class II(object):
def acallback(self, ignore):
self.J
I = II()
I.J = J
I.wr = weakref.ref(J, I.acallback)
# Now J and II are each in a self-cycle (as all new-style class
# objects are, since their __mro__ points back to them). I holds
# both a weak reference (I.wr) and a strong reference (I.J) to class
# J. I is also in a cycle (I.wr points to a weakref that references
# I.acallback). When we del these three, they all become trash, but
# the cycles prevent any of them from getting cleaned up immediately.
# Instead they have to wait for cyclic gc to deduce that they're
# trash.
#
# gc used to call tp_clear on all of them, and the order in which
# it does that is pretty accidental. The exact order in which we
# built up these things manages to provoke gc into running tp_clear
# in just the right order (I last). Calling tp_clear on II leaves
# behind an insane class object (its __mro__ becomes NULL). Calling
# tp_clear on J breaks its self-cycle, but J doesn't get deleted
# just then because of the strong reference from I.J. Calling
# tp_clear on I starts to clear I's __dict__, and just happens to
# clear I.J first -- I.wr is still intact. That removes the last
# reference to J, which triggers the weakref callback. The callback
# tries to do "self.J", and instances of new-style classes look up
# attributes ("J") in the class dict first. The class (II) wants to
# search II.__mro__, but that's NULL. The result was a segfault in
# a release build, and an assert failure in a debug build.
del I, J, II
gc.collect()
def test_callback_in_cycle_2(self):
import gc
# This is just like test_callback_in_cycle_1, except that II is an
# old-style class. The symptom is different then: an instance of an
# old-style class looks in its own __dict__ first. 'J' happens to
# get cleared from I.__dict__ before 'wr', and 'J' was never in II's
# __dict__, so the attribute isn't found. The difference is that
# the old-style II doesn't have a NULL __mro__ (it doesn't have any
# __mro__), so no segfault occurs. Instead it got:
# test_callback_in_cycle_2 (__main__.ReferencesTestCase) ...
# Exception exceptions.AttributeError:
# "II instance has no attribute 'J'" in <bound method II.acallback
# of <?.II instance at 0x00B9B4B8>> ignored
class J(object):
pass
class II:
def acallback(self, ignore):
self.J
I = II()
I.J = J
I.wr = weakref.ref(J, I.acallback)
del I, J, II
gc.collect()
def test_callback_in_cycle_3(self):
import gc
# This one broke the first patch that fixed the last two. In this
# case, the objects reachable from the callback aren't also reachable
# from the object (c1) *triggering* the callback: you can get to
# c1 from c2, but not vice-versa. The result was that c2's __dict__
# got tp_clear'ed by the time the c2.cb callback got invoked.
class C:
def cb(self, ignore):
self.me
self.c1
self.wr
c1, c2 = C(), C()
c2.me = c2
c2.c1 = c1
c2.wr = weakref.ref(c1, c2.cb)
del c1, c2
gc.collect()
def test_callback_in_cycle_4(self):
import gc
# Like test_callback_in_cycle_3, except c2 and c1 have different
# classes. c2's class (C) isn't reachable from c1 then, so protecting
# objects reachable from the dying object (c1) isn't enough to stop
# c2's class (C) from getting tp_clear'ed before c2.cb is invoked.
# The result was a segfault (C.__mro__ was NULL when the callback
# tried to look up self.me).
class C(object):
def cb(self, ignore):
self.me
self.c1
self.wr
class D:
pass
c1, c2 = D(), C()
c2.me = c2
c2.c1 = c1
c2.wr = weakref.ref(c1, c2.cb)
del c1, c2, C, D
gc.collect()
def test_callback_in_cycle_resurrection(self):
import gc
# Do something nasty in a weakref callback: resurrect objects
# from dead cycles. For this to be attempted, the weakref and
# its callback must also be part of the cyclic trash (else the
# objects reachable via the callback couldn't be in cyclic trash
# to begin with -- the callback would act like an external root).
# But gc clears trash weakrefs with callbacks early now, which
# disables the callbacks, so the callbacks shouldn't get called
# at all (and so nothing actually gets resurrected).
alist = []
class C(object):
def __init__(self, value):
self.attribute = value
def acallback(self, ignore):
alist.append(self.c)
c1, c2 = C(1), C(2)
c1.c = c2
c2.c = c1
c1.wr = weakref.ref(c2, c1.acallback)
c2.wr = weakref.ref(c1, c2.acallback)
def C_went_away(ignore):
alist.append("C went away")
wr = weakref.ref(C, C_went_away)
del c1, c2, C # make them all trash
self.assertEqual(alist, []) # del isn't enough to reclaim anything
gc.collect()
# c1.wr and c2.wr were part of the cyclic trash, so should have
# been cleared without their callbacks executing. OTOH, the weakref
# to C is bound to a function local (wr), and wasn't trash, so that
# callback should have been invoked when C went away.
self.assertEqual(alist, ["C went away"])
# The remaining weakref should be dead now (its callback ran).
self.assertEqual(wr(), None)
del alist[:]
gc.collect()
self.assertEqual(alist, [])
def test_callbacks_on_callback(self):
import gc
# Set up weakref callbacks *on* weakref callbacks.
alist = []
def safe_callback(ignore):
alist.append("safe_callback called")
class C(object):
def cb(self, ignore):
alist.append("cb called")
c, d = C(), C()
c.other = d
d.other = c
callback = c.cb
c.wr = weakref.ref(d, callback) # this won't trigger
d.wr = weakref.ref(callback, d.cb) # ditto
external_wr = weakref.ref(callback, safe_callback) # but this will
self.assertTrue(external_wr() is callback)
# The weakrefs attached to c and d should get cleared, so that
# C.cb is never called. But external_wr isn't part of the cyclic
# trash, and no cyclic trash is reachable from it, so safe_callback
# should get invoked when the bound method object callback (c.cb)
# -- which is itself a callback, and also part of the cyclic trash --
# gets reclaimed at the end of gc.
del callback, c, d, C
self.assertEqual(alist, []) # del isn't enough to clean up cycles
gc.collect()
self.assertEqual(alist, ["safe_callback called"])
self.assertEqual(external_wr(), None)
del alist[:]
gc.collect()
self.assertEqual(alist, [])
def test_gc_during_ref_creation(self):
self.check_gc_during_creation(weakref.ref)
def test_gc_during_proxy_creation(self):
self.check_gc_during_creation(weakref.proxy)
def check_gc_during_creation(self, makeref):
thresholds = gc.get_threshold()
gc.set_threshold(1, 1, 1)
gc.collect()
class A:
pass
def callback(*args):
pass
referenced = A()
a = A()
a.a = a
a.wr = makeref(referenced)
try:
# now make sure the object and the ref get labeled as
# cyclic trash:
a = A()
weakref.ref(referenced, callback)
finally:
gc.set_threshold(*thresholds)
def test_ref_created_during_del(self):
# Bug #1377858
# A weakref created in an object's __del__() would crash the
# interpreter when the weakref was cleaned up since it would refer to
# non-existent memory. This test should not segfault the interpreter.
class Target(object):
def __del__(self):
global ref_from_del
ref_from_del = weakref.ref(self)
w = Target()
def test_init(self):
# Issue 3634
# <weakref to class>.__init__() doesn't check errors correctly
r = weakref.ref(Exception)
self.assertRaises(TypeError, r.__init__, 0, 0, 0, 0, 0)
# No exception should be raised here
gc.collect()
def test_classes(self):
# Check that classes are weakrefable.
class A(object):
pass
l = []
weakref.ref(int)
a = weakref.ref(A, l.append)
A = None
gc.collect()
self.assertEqual(a(), None)
self.assertEqual(l, [a])
def test_equality(self):
# Alive weakrefs defer equality testing to their underlying object.
x = Object(1)
y = Object(1)
z = Object(2)
a = weakref.ref(x)
b = weakref.ref(y)
c = weakref.ref(z)
d = weakref.ref(x)
# Note how we directly test the operators here, to stress both
# __eq__ and __ne__.
self.assertTrue(a == b)
self.assertFalse(a != b)
self.assertFalse(a == c)
self.assertTrue(a != c)
self.assertTrue(a == d)
self.assertFalse(a != d)
del x, y, z
gc.collect()
for r in a, b, c:
# Sanity check
self.assertIs(r(), None)
# Dead weakrefs compare by identity: whether `a` and `d` are the
# same weakref object is an implementation detail, since they pointed
# to the same original object and didn't have a callback.
# (see issue #16453).
self.assertFalse(a == b)
self.assertTrue(a != b)
self.assertFalse(a == c)
self.assertTrue(a != c)
self.assertEqual(a == d, a is d)
self.assertEqual(a != d, a is not d)
def test_ordering(self):
# weakrefs cannot be ordered, even if the underlying objects can.
ops = [operator.lt, operator.gt, operator.le, operator.ge]
x = Object(1)
y = Object(1)
a = weakref.ref(x)
b = weakref.ref(y)
for op in ops:
self.assertRaises(TypeError, op, a, b)
# Same when dead.
del x, y
gc.collect()
for op in ops:
self.assertRaises(TypeError, op, a, b)
def test_hashing(self):
# Alive weakrefs hash the same as the underlying object
x = Object(42)
y = Object(42)
a = weakref.ref(x)
b = weakref.ref(y)
self.assertEqual(hash(a), hash(42))
del x, y
gc.collect()
# Dead weakrefs:
# - retain their hash is they were hashed when alive;
# - otherwise, cannot be hashed.
self.assertEqual(hash(a), hash(42))
self.assertRaises(TypeError, hash, b)
def test_trashcan_16602(self):
# Issue #16602: when a weakref's target was part of a long
# deallocation chain, the trashcan mechanism could delay clearing
# of the weakref and make the target object visible from outside
# code even though its refcount had dropped to 0. A crash ensued.
class C:
def __init__(self, parent):
if not parent:
return
wself = weakref.ref(self)
def cb(wparent):
o = wself()
self.wparent = weakref.ref(parent, cb)
d = weakref.WeakKeyDictionary()
root = c = C(None)
for n in range(100):
d[c] = c = C(c)
del root
gc.collect()
def test_callback_attribute(self):
x = Object(1)
callback = lambda ref: None
ref1 = weakref.ref(x, callback)
self.assertIs(ref1.__callback__, callback)
ref2 = weakref.ref(x)
self.assertIsNone(ref2.__callback__)
def test_callback_attribute_after_deletion(self):
x = Object(1)
ref = weakref.ref(x, self.callback)
self.assertIsNotNone(ref.__callback__)
del x
support.gc_collect()
self.assertIsNone(ref.__callback__)
def test_set_callback_attribute(self):
x = Object(1)
callback = lambda ref: None
ref1 = weakref.ref(x, callback)
with self.assertRaises(AttributeError):
ref1.__callback__ = lambda ref: None
class SubclassableWeakrefTestCase(TestBase):
def test_subclass_refs(self):
class MyRef(weakref.ref):
def __init__(self, ob, callback=None, value=42):
self.value = value
super().__init__(ob, callback)
def __call__(self):
self.called = True
return super().__call__()
o = Object("foo")
mr = MyRef(o, value=24)
self.assertTrue(mr() is o)
self.assertTrue(mr.called)
self.assertEqual(mr.value, 24)
del o
self.assertTrue(mr() is None)
self.assertTrue(mr.called)
def test_subclass_refs_dont_replace_standard_refs(self):
class MyRef(weakref.ref):
pass
o = Object(42)
r1 = MyRef(o)
r2 = weakref.ref(o)
self.assertTrue(r1 is not r2)
self.assertEqual(weakref.getweakrefs(o), [r2, r1])
self.assertEqual(weakref.getweakrefcount(o), 2)
r3 = MyRef(o)
self.assertEqual(weakref.getweakrefcount(o), 3)
refs = weakref.getweakrefs(o)
self.assertEqual(len(refs), 3)
self.assertTrue(r2 is refs[0])
self.assertIn(r1, refs[1:])
self.assertIn(r3, refs[1:])
def test_subclass_refs_dont_conflate_callbacks(self):
class MyRef(weakref.ref):
pass
o = Object(42)
r1 = MyRef(o, id)
r2 = MyRef(o, str)
self.assertTrue(r1 is not r2)
refs = weakref.getweakrefs(o)
self.assertIn(r1, refs)
self.assertIn(r2, refs)
def test_subclass_refs_with_slots(self):
class MyRef(weakref.ref):
__slots__ = "slot1", "slot2"
def __new__(type, ob, callback, slot1, slot2):
return weakref.ref.__new__(type, ob, callback)
def __init__(self, ob, callback, slot1, slot2):
self.slot1 = slot1
self.slot2 = slot2
def meth(self):
return self.slot1 + self.slot2
o = Object(42)
r = MyRef(o, None, "abc", "def")
self.assertEqual(r.slot1, "abc")
self.assertEqual(r.slot2, "def")
self.assertEqual(r.meth(), "abcdef")
self.assertFalse(hasattr(r, "__dict__"))
def test_subclass_refs_with_cycle(self):
# Bug #3110
# An instance of a weakref subclass can have attributes.
# If such a weakref holds the only strong reference to the object,
# deleting the weakref will delete the object. In this case,
# the callback must not be called, because the ref object is
# being deleted.
class MyRef(weakref.ref):
pass
# Use a local callback, for "regrtest -R::"
# to detect refcounting problems
def callback(w):
self.cbcalled += 1
o = C()
r1 = MyRef(o, callback)
r1.o = o
del o
del r1 # Used to crash here
self.assertEqual(self.cbcalled, 0)
# Same test, with two weakrefs to the same object
# (since code paths are different)
o = C()
r1 = MyRef(o, callback)
r2 = MyRef(o, callback)
r1.r = r2
r2.o = o
del o
del r2
del r1 # Used to crash here
self.assertEqual(self.cbcalled, 0)
class WeakMethodTestCase(unittest.TestCase):
def _subclass(self):
"""Return a Object subclass overriding `some_method`."""
class C(Object):
def some_method(self):
return 6
return C
def test_alive(self):
o = Object(1)
r = weakref.WeakMethod(o.some_method)
self.assertIsInstance(r, weakref.ReferenceType)
self.assertIsInstance(r(), type(o.some_method))
self.assertIs(r().__self__, o)
self.assertIs(r().__func__, o.some_method.__func__)
self.assertEqual(r()(), 4)
def test_object_dead(self):
o = Object(1)
r = weakref.WeakMethod(o.some_method)
del o
gc.collect()
self.assertIs(r(), None)
def test_method_dead(self):
C = self._subclass()
o = C(1)
r = weakref.WeakMethod(o.some_method)
del C.some_method
gc.collect()
self.assertIs(r(), None)
def test_callback_when_object_dead(self):
# Test callback behaviour when object dies first.
C = self._subclass()
calls = []
def cb(arg):
calls.append(arg)
o = C(1)
r = weakref.WeakMethod(o.some_method, cb)
del o
gc.collect()
self.assertEqual(calls, [r])
# Callback is only called once.
C.some_method = Object.some_method
gc.collect()
self.assertEqual(calls, [r])
def test_callback_when_method_dead(self):
# Test callback behaviour when method dies first.
C = self._subclass()
calls = []
def cb(arg):
calls.append(arg)
o = C(1)
r = weakref.WeakMethod(o.some_method, cb)
del C.some_method
gc.collect()
self.assertEqual(calls, [r])
# Callback is only called once.
del o
gc.collect()
self.assertEqual(calls, [r])
@support.cpython_only
def test_no_cycles(self):
# A WeakMethod doesn't create any reference cycle to itself.
o = Object(1)
def cb(_):
pass
r = weakref.WeakMethod(o.some_method, cb)
wr = weakref.ref(r)
del r
self.assertIs(wr(), None)
def test_equality(self):
def _eq(a, b):
self.assertTrue(a == b)
self.assertFalse(a != b)
def _ne(a, b):
self.assertTrue(a != b)
self.assertFalse(a == b)
x = Object(1)
y = Object(1)
a = weakref.WeakMethod(x.some_method)
b = weakref.WeakMethod(y.some_method)
c = weakref.WeakMethod(x.other_method)
d = weakref.WeakMethod(y.other_method)
# Objects equal, same method
_eq(a, b)
_eq(c, d)
# Objects equal, different method
_ne(a, c)
_ne(a, d)
_ne(b, c)
_ne(b, d)
# Objects unequal, same or different method
z = Object(2)
e = weakref.WeakMethod(z.some_method)
f = weakref.WeakMethod(z.other_method)
_ne(a, e)
_ne(a, f)
_ne(b, e)
_ne(b, f)
del x, y, z
gc.collect()
# Dead WeakMethods compare by identity
refs = a, b, c, d, e, f
for q in refs:
for r in refs:
self.assertEqual(q == r, q is r)
self.assertEqual(q != r, q is not r)
def test_hashing(self):
# Alive WeakMethods are hashable if the underlying object is
# hashable.
x = Object(1)
y = Object(1)
a = weakref.WeakMethod(x.some_method)
b = weakref.WeakMethod(y.some_method)
c = weakref.WeakMethod(y.other_method)
# Since WeakMethod objects are equal, the hashes should be equal.
self.assertEqual(hash(a), hash(b))
ha = hash(a)
# Dead WeakMethods retain their old hash value
del x, y
gc.collect()
self.assertEqual(hash(a), ha)
self.assertEqual(hash(b), ha)
# If it wasn't hashed when alive, a dead WeakMethod cannot be hashed.
self.assertRaises(TypeError, hash, c)
class MappingTestCase(TestBase):
COUNT = 10
def check_len_cycles(self, dict_type, cons):
N = 20
items = [RefCycle() for i in range(N)]
dct = dict_type(cons(o) for o in items)
# Keep an iterator alive
it = dct.items()
try:
next(it)
except StopIteration:
pass
del items
gc.collect()
n1 = len(dct)
del it
gc.collect()
n2 = len(dct)
# one item may be kept alive inside the iterator
self.assertIn(n1, (0, 1))
self.assertEqual(n2, 0)
def test_weak_keyed_len_cycles(self):
self.check_len_cycles(weakref.WeakKeyDictionary, lambda k: (k, 1))
def test_weak_valued_len_cycles(self):
self.check_len_cycles(weakref.WeakValueDictionary, lambda k: (1, k))
def check_len_race(self, dict_type, cons):
# Extended sanity checks for len() in the face of cyclic collection
self.addCleanup(gc.set_threshold, *gc.get_threshold())
for th in range(1, 100):
N = 20
gc.collect(0)
gc.set_threshold(th, th, th)
items = [RefCycle() for i in range(N)]
dct = dict_type(cons(o) for o in items)
del items
# All items will be collected at next garbage collection pass
it = dct.items()
try:
next(it)
except StopIteration:
pass
n1 = len(dct)
del it
n2 = len(dct)
self.assertGreaterEqual(n1, 0)
self.assertLessEqual(n1, N)
self.assertGreaterEqual(n2, 0)
self.assertLessEqual(n2, n1)
def test_weak_keyed_len_race(self):
self.check_len_race(weakref.WeakKeyDictionary, lambda k: (k, 1))
def test_weak_valued_len_race(self):
self.check_len_race(weakref.WeakValueDictionary, lambda k: (1, k))
def test_weak_values(self):
#
# This exercises d.copy(), d.items(), d[], del d[], len(d).
#
dict, objects = self.make_weak_valued_dict()
for o in objects:
self.assertEqual(weakref.getweakrefcount(o), 1)
self.assertTrue(o is dict[o.arg],
"wrong object returned by weak dict!")
items1 = list(dict.items())
items2 = list(dict.copy().items())
items1.sort()
items2.sort()
self.assertEqual(items1, items2,
"cloning of weak-valued dictionary did not work!")
del items1, items2
self.assertEqual(len(dict), self.COUNT)
del objects[0]
self.assertEqual(len(dict), self.COUNT - 1,
"deleting object did not cause dictionary update")
del objects, o
self.assertEqual(len(dict), 0,
"deleting the values did not clear the dictionary")
# regression on SF bug #447152:
dict = weakref.WeakValueDictionary()
self.assertRaises(KeyError, dict.__getitem__, 1)
dict[2] = C()
self.assertRaises(KeyError, dict.__getitem__, 2)
def test_weak_keys(self):
#
# This exercises d.copy(), d.items(), d[] = v, d[], del d[],
# len(d), k in d.
#
dict, objects = self.make_weak_keyed_dict()
for o in objects:
self.assertTrue(weakref.getweakrefcount(o) == 1,
"wrong number of weak references to %r!" % o)
self.assertTrue(o.arg is dict[o],
"wrong object returned by weak dict!")
items1 = dict.items()
items2 = dict.copy().items()
self.assertEqual(set(items1), set(items2),
"cloning of weak-keyed dictionary did not work!")
del items1, items2
self.assertEqual(len(dict), self.COUNT)
del objects[0]
self.assertTrue(len(dict) == (self.COUNT - 1),
"deleting object did not cause dictionary update")
del objects, o
self.assertTrue(len(dict) == 0,
"deleting the keys did not clear the dictionary")
o = Object(42)
dict[o] = "What is the meaning of the universe?"
self.assertIn(o, dict)
self.assertNotIn(34, dict)
def test_weak_keyed_iters(self):
dict, objects = self.make_weak_keyed_dict()
self.check_iters(dict)
# Test keyrefs()
refs = dict.keyrefs()
self.assertEqual(len(refs), len(objects))
objects2 = list(objects)
for wr in refs:
ob = wr()
self.assertIn(ob, dict)
self.assertIn(ob, dict)
self.assertEqual(ob.arg, dict[ob])
objects2.remove(ob)
self.assertEqual(len(objects2), 0)
# Test iterkeyrefs()
objects2 = list(objects)
self.assertEqual(len(list(dict.keyrefs())), len(objects))
for wr in dict.keyrefs():
ob = wr()
self.assertIn(ob, dict)
self.assertIn(ob, dict)
self.assertEqual(ob.arg, dict[ob])
objects2.remove(ob)
self.assertEqual(len(objects2), 0)
def test_weak_valued_iters(self):
dict, objects = self.make_weak_valued_dict()
self.check_iters(dict)
# Test valuerefs()
refs = dict.valuerefs()
self.assertEqual(len(refs), len(objects))
objects2 = list(objects)
for wr in refs:
ob = wr()
self.assertEqual(ob, dict[ob.arg])
self.assertEqual(ob.arg, dict[ob.arg].arg)
objects2.remove(ob)
self.assertEqual(len(objects2), 0)
# Test itervaluerefs()
objects2 = list(objects)
self.assertEqual(len(list(dict.itervaluerefs())), len(objects))
for wr in dict.itervaluerefs():
ob = wr()
self.assertEqual(ob, dict[ob.arg])
self.assertEqual(ob.arg, dict[ob.arg].arg)
objects2.remove(ob)
self.assertEqual(len(objects2), 0)
def check_iters(self, dict):
# item iterator:
items = list(dict.items())
for item in dict.items():
items.remove(item)
self.assertFalse(items, "items() did not touch all items")
# key iterator, via __iter__():
keys = list(dict.keys())
for k in dict:
keys.remove(k)
self.assertFalse(keys, "__iter__() did not touch all keys")
# key iterator, via iterkeys():
keys = list(dict.keys())
for k in dict.keys():
keys.remove(k)
self.assertFalse(keys, "iterkeys() did not touch all keys")
# value iterator:
values = list(dict.values())
for v in dict.values():
values.remove(v)
self.assertFalse(values,
"itervalues() did not touch all values")
def check_weak_destroy_while_iterating(self, dict, objects, iter_name):
n = len(dict)
it = iter(getattr(dict, iter_name)())
next(it) # Trigger internal iteration
# Destroy an object
del objects[-1]
gc.collect() # just in case
# We have removed either the first consumed object, or another one
self.assertIn(len(list(it)), [len(objects), len(objects) - 1])
del it
# The removal has been committed
self.assertEqual(len(dict), n - 1)
def check_weak_destroy_and_mutate_while_iterating(self, dict, testcontext):
# Check that we can explicitly mutate the weak dict without
# interfering with delayed removal.
# `testcontext` should create an iterator, destroy one of the
# weakref'ed objects and then return a new key/value pair corresponding
# to the destroyed object.
with testcontext() as (k, v):
self.assertNotIn(k, dict)
with testcontext() as (k, v):
self.assertRaises(KeyError, dict.__delitem__, k)
self.assertNotIn(k, dict)
with testcontext() as (k, v):
self.assertRaises(KeyError, dict.pop, k)
self.assertNotIn(k, dict)
with testcontext() as (k, v):
dict[k] = v
self.assertEqual(dict[k], v)
ddict = copy.copy(dict)
with testcontext() as (k, v):
dict.update(ddict)
self.assertEqual(dict, ddict)
with testcontext() as (k, v):
dict.clear()
self.assertEqual(len(dict), 0)
def test_weak_keys_destroy_while_iterating(self):
# Issue #7105: iterators shouldn't crash when a key is implicitly removed
dict, objects = self.make_weak_keyed_dict()
self.check_weak_destroy_while_iterating(dict, objects, 'keys')
self.check_weak_destroy_while_iterating(dict, objects, 'items')
self.check_weak_destroy_while_iterating(dict, objects, 'values')
self.check_weak_destroy_while_iterating(dict, objects, 'keyrefs')
dict, objects = self.make_weak_keyed_dict()
@contextlib.contextmanager
def testcontext():
try:
it = iter(dict.items())
next(it)
# Schedule a key/value for removal and recreate it
v = objects.pop().arg
gc.collect() # just in case
yield Object(v), v
finally:
it = None # should commit all removals
self.check_weak_destroy_and_mutate_while_iterating(dict, testcontext)
def test_weak_values_destroy_while_iterating(self):
# Issue #7105: iterators shouldn't crash when a key is implicitly removed
dict, objects = self.make_weak_valued_dict()
self.check_weak_destroy_while_iterating(dict, objects, 'keys')
self.check_weak_destroy_while_iterating(dict, objects, 'items')
self.check_weak_destroy_while_iterating(dict, objects, 'values')
self.check_weak_destroy_while_iterating(dict, objects, 'itervaluerefs')
self.check_weak_destroy_while_iterating(dict, objects, 'valuerefs')
dict, objects = self.make_weak_valued_dict()
@contextlib.contextmanager
def testcontext():
try:
it = iter(dict.items())
next(it)
# Schedule a key/value for removal and recreate it
k = objects.pop().arg
gc.collect() # just in case
yield k, Object(k)
finally:
it = None # should commit all removals
self.check_weak_destroy_and_mutate_while_iterating(dict, testcontext)
def test_make_weak_keyed_dict_from_dict(self):
o = Object(3)
dict = weakref.WeakKeyDictionary({o:364})
self.assertEqual(dict[o], 364)
def test_make_weak_keyed_dict_from_weak_keyed_dict(self):
o = Object(3)
dict = weakref.WeakKeyDictionary({o:364})
dict2 = weakref.WeakKeyDictionary(dict)
self.assertEqual(dict[o], 364)
def make_weak_keyed_dict(self):
dict = weakref.WeakKeyDictionary()
objects = list(map(Object, range(self.COUNT)))
for o in objects:
dict[o] = o.arg
return dict, objects
def test_make_weak_valued_dict_from_dict(self):
o = Object(3)
dict = weakref.WeakValueDictionary({364:o})
self.assertEqual(dict[364], o)
def test_make_weak_valued_dict_from_weak_valued_dict(self):
o = Object(3)
dict = weakref.WeakValueDictionary({364:o})
dict2 = weakref.WeakValueDictionary(dict)
self.assertEqual(dict[364], o)
def make_weak_valued_dict(self):
dict = weakref.WeakValueDictionary()
objects = list(map(Object, range(self.COUNT)))
for o in objects:
dict[o.arg] = o
return dict, objects
def check_popitem(self, klass, key1, value1, key2, value2):
weakdict = klass()
weakdict[key1] = value1
weakdict[key2] = value2
self.assertEqual(len(weakdict), 2)
k, v = weakdict.popitem()
self.assertEqual(len(weakdict), 1)
if k is key1:
self.assertTrue(v is value1)
else:
self.assertTrue(v is value2)
k, v = weakdict.popitem()
self.assertEqual(len(weakdict), 0)
if k is key1:
self.assertTrue(v is value1)
else:
self.assertTrue(v is value2)
def test_weak_valued_dict_popitem(self):
self.check_popitem(weakref.WeakValueDictionary,
"key1", C(), "key2", C())
def test_weak_keyed_dict_popitem(self):
self.check_popitem(weakref.WeakKeyDictionary,
C(), "value 1", C(), "value 2")
def check_setdefault(self, klass, key, value1, value2):
self.assertTrue(value1 is not value2,
"invalid test"
" -- value parameters must be distinct objects")
weakdict = klass()
o = weakdict.setdefault(key, value1)
self.assertTrue(o is value1)
self.assertIn(key, weakdict)
self.assertTrue(weakdict.get(key) is value1)
self.assertTrue(weakdict[key] is value1)
o = weakdict.setdefault(key, value2)
self.assertTrue(o is value1)
self.assertIn(key, weakdict)
self.assertTrue(weakdict.get(key) is value1)
self.assertTrue(weakdict[key] is value1)
def test_weak_valued_dict_setdefault(self):
self.check_setdefault(weakref.WeakValueDictionary,
"key", C(), C())
def test_weak_keyed_dict_setdefault(self):
self.check_setdefault(weakref.WeakKeyDictionary,
C(), "value 1", "value 2")
def check_update(self, klass, dict):
#
# This exercises d.update(), len(d), d.keys(), k in d,
# d.get(), d[].
#
weakdict = klass()
weakdict.update(dict)
self.assertEqual(len(weakdict), len(dict))
for k in weakdict.keys():
self.assertIn(k, dict, "mysterious new key appeared in weak dict")
v = dict.get(k)
self.assertTrue(v is weakdict[k])
self.assertTrue(v is weakdict.get(k))
for k in dict.keys():
self.assertIn(k, weakdict, "original key disappeared in weak dict")
v = dict[k]
self.assertTrue(v is weakdict[k])
self.assertTrue(v is weakdict.get(k))
def test_weak_valued_dict_update(self):
self.check_update(weakref.WeakValueDictionary,
{1: C(), 'a': C(), C(): C()})
def test_weak_keyed_dict_update(self):
self.check_update(weakref.WeakKeyDictionary,
{C(): 1, C(): 2, C(): 3})
def test_weak_keyed_delitem(self):
d = weakref.WeakKeyDictionary()
o1 = Object('1')
o2 = Object('2')
d[o1] = 'something'
d[o2] = 'something'
self.assertEqual(len(d), 2)
del d[o1]
self.assertEqual(len(d), 1)
self.assertEqual(list(d.keys()), [o2])
def test_weak_valued_delitem(self):
d = weakref.WeakValueDictionary()
o1 = Object('1')
o2 = Object('2')
d['something'] = o1
d['something else'] = o2
self.assertEqual(len(d), 2)
del d['something']
self.assertEqual(len(d), 1)
self.assertTrue(list(d.items()) == [('something else', o2)])
def test_weak_keyed_bad_delitem(self):
d = weakref.WeakKeyDictionary()
o = Object('1')
# An attempt to delete an object that isn't there should raise
# KeyError. It didn't before 2.3.
self.assertRaises(KeyError, d.__delitem__, o)
self.assertRaises(KeyError, d.__getitem__, o)
# If a key isn't of a weakly referencable type, __getitem__ and
# __setitem__ raise TypeError. __delitem__ should too.
self.assertRaises(TypeError, d.__delitem__, 13)
self.assertRaises(TypeError, d.__getitem__, 13)
self.assertRaises(TypeError, d.__setitem__, 13, 13)
def test_weak_keyed_cascading_deletes(self):
# SF bug 742860. For some reason, before 2.3 __delitem__ iterated
# over the keys via self.data.iterkeys(). If things vanished from
# the dict during this (or got added), that caused a RuntimeError.
d = weakref.WeakKeyDictionary()
mutate = False
class C(object):
def __init__(self, i):
self.value = i
def __hash__(self):
return hash(self.value)
def __eq__(self, other):
if mutate:
# Side effect that mutates the dict, by removing the
# last strong reference to a key.
del objs[-1]
return self.value == other.value
objs = [C(i) for i in range(4)]
for o in objs:
d[o] = o.value
del o # now the only strong references to keys are in objs
# Find the order in which iterkeys sees the keys.
objs = list(d.keys())
# Reverse it, so that the iteration implementation of __delitem__
# has to keep looping to find the first object we delete.
objs.reverse()
# Turn on mutation in C.__eq__. The first time thru the loop,
# under the iterkeys() business the first comparison will delete
# the last item iterkeys() would see, and that causes a
# RuntimeError: dictionary changed size during iteration
# when the iterkeys() loop goes around to try comparing the next
# key. After this was fixed, it just deletes the last object *our*
# "for o in obj" loop would have gotten to.
mutate = True
count = 0
for o in objs:
count += 1
del d[o]
self.assertEqual(len(d), 0)
self.assertEqual(count, 2)
from test import mapping_tests
class WeakValueDictionaryTestCase(mapping_tests.BasicTestMappingProtocol):
"""Check that WeakValueDictionary conforms to the mapping protocol"""
__ref = {"key1":Object(1), "key2":Object(2), "key3":Object(3)}
type2test = weakref.WeakValueDictionary
def _reference(self):
return self.__ref.copy()
class WeakKeyDictionaryTestCase(mapping_tests.BasicTestMappingProtocol):
"""Check that WeakKeyDictionary conforms to the mapping protocol"""
__ref = {Object("key1"):1, Object("key2"):2, Object("key3"):3}
type2test = weakref.WeakKeyDictionary
def _reference(self):
return self.__ref.copy()
class FinalizeTestCase(unittest.TestCase):
class A:
pass
def _collect_if_necessary(self):
# we create no ref-cycles so in CPython no gc should be needed
if sys.implementation.name != 'cpython':
support.gc_collect()
def test_finalize(self):
def add(x,y,z):
res.append(x + y + z)
return x + y + z
a = self.A()
res = []
f = weakref.finalize(a, add, 67, 43, z=89)
self.assertEqual(f.alive, True)
self.assertEqual(f.peek(), (a, add, (67,43), {'z':89}))
self.assertEqual(f(), 199)
self.assertEqual(f(), None)
self.assertEqual(f(), None)
self.assertEqual(f.peek(), None)
self.assertEqual(f.detach(), None)
self.assertEqual(f.alive, False)
self.assertEqual(res, [199])
res = []
f = weakref.finalize(a, add, 67, 43, 89)
self.assertEqual(f.peek(), (a, add, (67,43,89), {}))
self.assertEqual(f.detach(), (a, add, (67,43,89), {}))
self.assertEqual(f(), None)
self.assertEqual(f(), None)
self.assertEqual(f.peek(), None)
self.assertEqual(f.detach(), None)
self.assertEqual(f.alive, False)
self.assertEqual(res, [])
res = []
f = weakref.finalize(a, add, x=67, y=43, z=89)
del a
self._collect_if_necessary()
self.assertEqual(f(), None)
self.assertEqual(f(), None)
self.assertEqual(f.peek(), None)
self.assertEqual(f.detach(), None)
self.assertEqual(f.alive, False)
self.assertEqual(res, [199])
def test_order(self):
a = self.A()
res = []
f1 = weakref.finalize(a, res.append, 'f1')
f2 = weakref.finalize(a, res.append, 'f2')
f3 = weakref.finalize(a, res.append, 'f3')
f4 = weakref.finalize(a, res.append, 'f4')
f5 = weakref.finalize(a, res.append, 'f5')
# make sure finalizers can keep themselves alive
del f1, f4
self.assertTrue(f2.alive)
self.assertTrue(f3.alive)
self.assertTrue(f5.alive)
self.assertTrue(f5.detach())
self.assertFalse(f5.alive)
f5() # nothing because previously unregistered
res.append('A')
f3() # => res.append('f3')
self.assertFalse(f3.alive)
res.append('B')
f3() # nothing because previously called
res.append('C')
del a
self._collect_if_necessary()
# => res.append('f4')
# => res.append('f2')
# => res.append('f1')
self.assertFalse(f2.alive)
res.append('D')
f2() # nothing because previously called by gc
expected = ['A', 'f3', 'B', 'C', 'f4', 'f2', 'f1', 'D']
self.assertEqual(res, expected)
def test_all_freed(self):
# we want a weakrefable subclass of weakref.finalize
class MyFinalizer(weakref.finalize):
pass
a = self.A()
res = []
def callback():
res.append(123)
f = MyFinalizer(a, callback)
wr_callback = weakref.ref(callback)
wr_f = weakref.ref(f)
del callback, f
self.assertIsNotNone(wr_callback())
self.assertIsNotNone(wr_f())
del a
self._collect_if_necessary()
self.assertIsNone(wr_callback())
self.assertIsNone(wr_f())
self.assertEqual(res, [123])
@classmethod
def run_in_child(cls):
def error():
# Create an atexit finalizer from inside a finalizer called
# at exit. This should be the next to be run.
g1 = weakref.finalize(cls, print, 'g1')
print('f3 error')
1/0
# cls should stay alive till atexit callbacks run
f1 = weakref.finalize(cls, print, 'f1', _global_var)
f2 = weakref.finalize(cls, print, 'f2', _global_var)
f3 = weakref.finalize(cls, error)
f4 = weakref.finalize(cls, print, 'f4', _global_var)
assert f1.atexit == True
f2.atexit = False
assert f3.atexit == True
assert f4.atexit == True
def test_atexit(self):
prog = ('from test.test_weakref import FinalizeTestCase;'+
'FinalizeTestCase.run_in_child()')
rc, out, err = script_helper.assert_python_ok('-c', prog)
out = out.decode('ascii').splitlines()
self.assertEqual(out, ['f4 foobar', 'f3 error', 'g1', 'f1 foobar'])
self.assertTrue(b'ZeroDivisionError' in err)
libreftest = """ Doctest for examples in the library reference: weakref.rst
>>> import weakref
>>> class Dict(dict):
... pass
...
>>> obj = Dict(red=1, green=2, blue=3) # this object is weak referencable
>>> r = weakref.ref(obj)
>>> print(r() is obj)
True
>>> import weakref
>>> class Object:
... pass
...
>>> o = Object()
>>> r = weakref.ref(o)
>>> o2 = r()
>>> o is o2
True
>>> del o, o2
>>> print(r())
None
>>> import weakref
>>> class ExtendedRef(weakref.ref):
... def __init__(self, ob, callback=None, **annotations):
... super().__init__(ob, callback)
... self.__counter = 0
... for k, v in annotations.items():
... setattr(self, k, v)
... def __call__(self):
... '''Return a pair containing the referent and the number of
... times the reference has been called.
... '''
... ob = super().__call__()
... if ob is not None:
... self.__counter += 1
... ob = (ob, self.__counter)
... return ob
...
>>> class A: # not in docs from here, just testing the ExtendedRef
... pass
...
>>> a = A()
>>> r = ExtendedRef(a, foo=1, bar="baz")
>>> r.foo
1
>>> r.bar
'baz'
>>> r()[1]
1
>>> r()[1]
2
>>> r()[0] is a
True
>>> import weakref
>>> _id2obj_dict = weakref.WeakValueDictionary()
>>> def remember(obj):
... oid = id(obj)
... _id2obj_dict[oid] = obj
... return oid
...
>>> def id2obj(oid):
... return _id2obj_dict[oid]
...
>>> a = A() # from here, just testing
>>> a_id = remember(a)
>>> id2obj(a_id) is a
True
>>> del a
>>> try:
... id2obj(a_id)
... except KeyError:
... print('OK')
... else:
... print('WeakValueDictionary error')
OK
"""
__test__ = {'libreftest' : libreftest}
def test_main():
support.run_unittest(
ReferencesTestCase,
WeakMethodTestCase,
MappingTestCase,
WeakValueDictionaryTestCase,
WeakKeyDictionaryTestCase,
SubclassableWeakrefTestCase,
FinalizeTestCase,
)
support.run_doctest(sys.modules[__name__])
if __name__ == "__main__":
test_main()
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