[issue30469] Inconsistent Execution of Generic Descriptor Attributes
Ryan Morshead
report at bugs.python.org
Wed May 24 20:13:08 EDT 2017
New submission from Ryan Morshead:
When the `__get__`, `__set__`, or `__delete__` attribute of a descriptor is not a method, and is instead a generic callable, the first argument of that callable is inconsistent:
class Callable(object):
def __call__(self, first, *args, **kwargs):
print(first)
class Descriptor(object):
__set__ = Callable()
__delete__ = Callable()
__get__ = Callable()
class MyClass(object):
d = Descriptor()
mc = MyClass()
mc.d = 1
del mc.d
mc.d
Prints:
<__main__.MyClass object at 0x10854cda0>
<__main__.MyClass object at 0x10854cda0>
<__main__.Descriptor object at 0x10855f240>
As it turns out, this occurs because `slot_tp_descr_set` (shared by `__set__` and `__delete__`) and `slot_tp_descr_get` just aren't consistent in their implementation.
See: https://stackoverflow.com/questions/44169370/strange-descriptor-behavior/44169805#44169805
Is this behavior intentional? If not, how ought this case be handled?
----------
components: ctypes
messages: 294415
nosy: Ryan Morshead
priority: normal
severity: normal
status: open
title: Inconsistent Execution of Generic Descriptor Attributes
type: behavior
versions: Python 2.7
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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue30469>
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