Issue 34830: functools.partial is weak referncable (original) (raw)

Issue34830

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This issue has been migrated to GitHub: https://github.com/python/cpython/issues/79011

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Created on 2018-09-28 09:20 by mdk, last changed 2022-04-11 14:59 by admin. This issue is now closed.

Messages (5)
msg326617 - (view)	Author: Julien Palard (mdk) *	Date: 2018-09-28 09:20
According to the doc: :class:`partial` objects are like :class:`function` objects in that they are callable, weak referencable, and can have attributes. I don't understand why "weak" here, and it's the only occurence of "weak referencable" in the documentation. I don't see an object in Python being referencable but NOT weak referencable, do I miss something obvious here?
msg326619 - (view)	Author: Andrew Svetlov (asvetlov) *	Date: 2018-09-28 09:36
``` In [1]: import weakref In [2]: class A: ...: __slots__ = () In [3]: weakref.ref(A()) --------------------------------------------------------------------------- TypeError Traceback (most recent call last) in ----> 1 weakref.ref(A()) TypeError: cannot create weak reference to 'A' object ```
msg326621 - (view)	Author: Julien Palard (mdk) *	Date: 2018-09-28 09:42
TIL. So it really make sense in this context to tell a functools.partial is weak referencable?
msg326622 - (view)	Author: Andrew Svetlov (asvetlov) *	Date: 2018-09-28 09:43
I think yes.
msg326623 - (view)	Author: Serhiy Storchaka (serhiy.storchaka) *	Date: 2018-09-28 09:50
Instances of many builtin types are not weak referencable. >>> weakref.ref(0) Traceback (most recent call last): File "", line 1, in TypeError: cannot create weak reference to 'int' object >>> weakref.ref([]) Traceback (most recent call last): File "", line 1, in TypeError: cannot create weak reference to 'list' object