[Python-bugs-list] [ python-Bugs-813299 ] Weak references and bound functions interact in a bad way

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Bugs item #813299, was opened at 2003-09-26 23:20
Message generated for change (Comment added) made by loewis
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Category: Python Interpreter Core
Group: Python 2.3
>Status: Closed
>Resolution: Invalid
Priority: 5
Submitted By: Matthias Klose (doko)
Assigned to: Nobody/Anonymous (nobody)
Summary: Weak references and bound functions interact in a bad way

Initial Comment:
[forwarded from http://bugs.debian.org/211129]



>>> import weakref

>>> class Foo:

...     def bar(self):

...             print 'Hello'

... 

>>> x=Foo()

>>> y=weakref.ref(x.bar)

>>> y

<weakref at 0x4021cb94; dead>



  This behavior is self-evidently wrong, and seems to

be due to an

implementation detail of Python.  There is a workaround

available here:

http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/81253

(I haven't

examined it closely, but it looks like it should work)

 Nevertheless, this

should be fixed eventually IMO.





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>Comment By: Martin v. Löwis (loewis)
Date: 2003-09-27 09:50

Message:
Logged In: YES 
user_id=21627

I fail to see a bug here. x.bar creates a new object (a

bound method),

for which then a weak reference is created. Since there is

no strong

reference to the same bound method, the bound method is

deleted, and

the weak reference dies.



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