bpo-27141: Fix collections.UserList and UserDict shallow copy. (GH-4094)

This commit is contained in:
Bar Harel 2019-05-19 16:57:13 +03:00 committed by Serhiy Storchaka
parent c661b30f89
commit f4e1babf44
3 changed files with 41 additions and 0 deletions

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@ -1038,6 +1038,13 @@ class UserDict(_collections_abc.MutableMapping):
# Now, add the methods in dicts but not in MutableMapping
def __repr__(self): return repr(self.data)
def __copy__(self):
inst = self.__class__.__new__(self.__class__)
inst.__dict__.update(self.__dict__)
# Create a copy and avoid triggering descriptors
inst.__dict__["data"] = self.__dict__["data"].copy()
return inst
def copy(self):
if self.__class__ is UserDict:
return UserDict(self.data.copy())
@ -1050,6 +1057,7 @@ class UserDict(_collections_abc.MutableMapping):
self.data = data
c.update(self)
return c
@classmethod
def fromkeys(cls, iterable, value=None):
d = cls()
@ -1118,6 +1126,12 @@ class UserList(_collections_abc.MutableSequence):
def __imul__(self, n):
self.data *= n
return self
def __copy__(self):
inst = self.__class__.__new__(self.__class__)
inst.__dict__.update(self.__dict__)
# Create a copy and avoid triggering descriptors
inst.__dict__["data"] = self.__dict__["data"][:]
return inst
def append(self, item): self.data.append(item)
def insert(self, i, item): self.data.insert(i, item)
def pop(self, i=-1): return self.data.pop(i)

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@ -37,6 +37,20 @@ class TestUserObjects(unittest.TestCase):
b=b.__name__,
),
)
def _copy_test(self, obj):
# Test internal copy
obj_copy = obj.copy()
self.assertIsNot(obj.data, obj_copy.data)
self.assertEqual(obj.data, obj_copy.data)
# Test copy.copy
obj.test = [1234] # Make sure instance vars are also copied.
obj_copy = copy.copy(obj)
self.assertIsNot(obj.data, obj_copy.data)
self.assertEqual(obj.data, obj_copy.data)
self.assertIs(obj.test, obj_copy.test)
def test_str_protocol(self):
self._superset_test(UserString, str)
@ -46,6 +60,16 @@ class TestUserObjects(unittest.TestCase):
def test_dict_protocol(self):
self._superset_test(UserDict, dict)
def test_list_copy(self):
obj = UserList()
obj.append(123)
self._copy_test(obj)
def test_dict_copy(self):
obj = UserDict()
obj[123] = "abc"
self._copy_test(obj)
################################################################################
### ChainMap (helper class for configparser and the string module)

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@ -0,0 +1,3 @@
Added a ``__copy__()`` to ``collections.UserList`` and
``collections.UserDict`` in order to correctly implement shallow copying of
the objects. Patch by Bar Harel.