8000 bpo-36743: __get__ is sometimes called without the owner argument (GH… · python/cpython@c71ae1a · GitHub
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bpo-36743: __get__ is sometimes called without the owner argument (GH-12992) (GH-15589)
(cherry picked from commit 0dac68f) Co-authored-by: Raymond Hettinger <rhettinger@users.noreply.github.com>
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‎Doc/reference/datamodel.rst

Lines changed: 18 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -1618,21 +1618,32 @@ refers to the attribute whose name is the key of the property in the owner
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class' :attr:`~object.__dict__`.
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.. method:: object.__get__(self, instance, owner)
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.. method:: object.__get__(self, instance, owner=None)
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Called to get the attribute of the owner class (class attribute access) or of an
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instance of that class (instance attribute access). *owner* is always the owner
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class, while *instance* is the instance that the attribute was accessed through,
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or ``None`` when the attribute is accessed through the *owner*. This method
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should return the (computed) attribute value or raise an :exc:`AttributeError`
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exception.
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Called to get the attribute of the owner class (class attribute access) or
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of an instance of that class (instance attribute access). The optional
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*owner* argument is the owner class, while *instance* is the instance that
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the attribute was accessed through, or ``None`` when the attribute is
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accessed through the *owner*.
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This method should return the computed attribute value or raise an
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:exc:`AttributeError` exception.
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:PEP:`252` specifies that :meth:`__get__` is callable with one or two
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arguments. Python's own built-in descriptors support this specification;
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however, it is likely that some third-party tools have descriptors
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that require both arguments. Python's own :meth:`__getattribute__`
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implementation always passes in both arguments whether they are required
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or not.
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.. method:: object.__set__(self, instance, value)
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Called to set the attribute on an instance *instance* of the owner class to a
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new value, *value*.
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Note, adding :meth:`__set__` or :meth:`__delete__` changes the kind of
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descriptor to a "data descriptor". See :ref:`descriptor-invocation` for
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more details.
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.. method:: object.__delete__(self, instance)
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‎Lib/_pyio.py

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -281,7 +281,7 @@ def _open_code_with_warning(path):
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class DocDescriptor:
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"""Helper for builtins.open.__doc__
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"""
284-
def __get__(self, obj, typ):
284+
def __get__(self, obj, typ=None):
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return (
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"open(file, mode='r', buffering=-1, encoding=None, "
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"errors=None, newline=None, closefd=True)\n\n" +

‎Lib/functools.py

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -400,7 +400,7 @@ def _method(cls_or_self, /, *args, **keywords):
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_method._partialmethod = self
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return _method
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403-
def __get__(self, obj, cls):
403+
def __get__(self, obj, cls=None):
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get = getattr(self.func, "__get__", None)
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result = None
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if get is not None:
@@ -905,7 +905,7 @@ def register(self, cls, method=None):
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"""
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return self.dispatcher.register(cls, func=method)
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908-
def __get__(self, obj, cls):
908+
def __get__(self, obj, cls=None):
909909
def _method(*args, **kwargs):
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method = self.dispatcher.dispatch(args[0].__class__)
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return method.__get__(obj, cls)(*args, **kwargs)
@@ -943,7 +943,7 @@ def __set_name__(self, owner, name):
943943
f"({self.attrname!r} and {name!r})."
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)
945945

946-
def __get__(self, instance, owner):
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def __get__(self, instance, owner=None):
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if instance is None:
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return self
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if self.attrname is None:

‎Lib/unittest/mock.py

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -2806,7 +2806,7 @@ class PropertyMock(Mock):
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def _get_child_mock(self, /, **kwargs):
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return MagicMock(**kwargs)
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2809-
def __get__(self, obj, obj_type):
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def __get__(self, obj, obj_type=None):
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return self()
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def __set__(self, obj, val):
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self(val)

‎Tools/demo/eiffel.py

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -78,7 +78,7 @@ def __init__(self, func, pre, post):
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self.__name__ = func.__name__
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self.__doc__ = func.__doc__
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81-
def __get__(self, obj, cls):
81+
def __get__(self, obj, cls=None):
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return EiffelMethodWrapper(obj, self)
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8484
def callmethod(self, inst, args, kwargs):

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