[issue24123] Python 2.7 Tutorial Conflicting behavior with WeakValueDictionary.
R. David Murray added the comment: Well, technically it is probably not a bug. IPython is doubtless holding on to a reference to 'a' because it was defined at the prompt. Perhaps it could use a weakvaluedict for that, though :) On the other hand they might consider it a feature that objects don't go out of scope. -- stage: - resolved ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue24123 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue24123] Python 2.7 Tutorial Conflicting behavior with WeakValueDictionary.
New submission from Jesse Bacon: https://docs.python.org/2/tutorial/stdlib2.html Section 11.6. Weak References The example code below from the python tutorial suggests that the value of a is no persistent when cast into a WeakValueDictionary as entry 'primary' The value persisted in the dictionary aver 'a' was deleted and garbage collection had been called. I did not see a bug report for this already forgive me if there was one already put in. import weakref, gc class A: def __init__(self, value): self.value = value def __repr__(self): return str(self.value) a = A(10) # create a reference d = weakref.WeakValueDictionary() d['primary'] = a# does not create a reference d['primary']# fetch the object if it is still alive del a # remove the one reference gc.collect()# run garbage collection right away d['primary']# entry was automatically removed -- components: Demos and Tools messages: 242534 nosy: jessembacon priority: normal severity: normal status: open title: Python 2.7 Tutorial Conflicting behavior with WeakValueDictionary. type: behavior versions: Python 2.7 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue24123 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue24123] Python 2.7 Tutorial Conflicting behavior with WeakValueDictionary.
Jesse Bacon added the comment: https://docs.python.org/2/tutorial/stdlib2.html Section 11.6. Weak References The example code below from the python tutorial suggests that the value of 'a' is not persistent when cast into a WeakValueDictionary as entry 'primary' The value persisted in the dictionary aver 'a' was deleted and garbage collection had been called. I did not see a bug report for this already forgive me if there was one already put in. import weakref, gc class A: def __init__(self, value): self.value = value def __repr__(self): return str(self.value) a = A(10) # create a reference d = weakref.WeakValueDictionary() d['primary'] = a# does not create a reference d['primary']# fetch the object if it is still alive del a # remove the one reference gc.collect()# run garbage collection right away d['primary']# entry was automatically removed -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue24123 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue24123] Python 2.7 Tutorial Conflicting behavior with WeakValueDictionary.
Jesse Bacon added the comment: https://docs.python.org/2/tutorial/stdlib2.html Section 11.6. Weak References The example code below from the python tutorial suggests that the value of 'a' is not persistent when cast into a WeakValueDictionary as entry 'primary' The value persisted in the dictionary after 'a' was deleted and garbage collection had been called. I did not see a bug report for this already forgive me if there was one already put in. import weakref, gc class A: def __init__(self, value): self.value = value def __repr__(self): return str(self.value) a = A(10) # create a reference d = weakref.WeakValueDictionary() d['primary'] = a# does not create a reference d['primary']# fetch the object if it is still alive del a # remove the one reference gc.collect()# run garbage collection right away d['primary']# entry was automatically removed -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue24123 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue24123] Python 2.7 Tutorial Conflicting behavior with WeakValueDictionary.
R. David Murray added the comment: If I run the example code you pasted using 2.7, I get a KeyError. So the example looks correct to me. -- nosy: +r.david.murray ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue24123 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue24123] Python 2.7 Tutorial Conflicting behavior with WeakValueDictionary.
Jesse Bacon added the comment: Thank you for the second eyes. I just verified that it works using the standard python shell. It looks like the bug is in IPython. I’ll post it there. In [7]: class A: ...: def __init__(self, value): ...: self.value = value ...: def __repr__(self): ...: return str(self.value) ...: In [8]: a = A(10) In [9]: d = weakref.WeakValueDictionary() In [10]: d['primary'] = a In [11]: d['primary'] Out[11]: 10 In [12]: del a In [13]: gc.collect() Out[13]: 148 In [14]: d['primary'] Out[14]: 10 In [15]: sincerely, Jesse Bacon On May 3, 2015, at 8:54 PM, R. David Murray rep...@bugs.python.org wrote: R. David Murray added the comment: If I run the example code you pasted using 2.7, I get a KeyError. So the example looks correct to me. -- nosy: +r.david.murray ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue24123 ___ -- title: Python 2.7 Tutorial Conflicting behavior with WeakValueDictionary. - Python 2.7 Tutorial Conflicting behavior with WeakValueDictionary. ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue24123 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue24123] Python 2.7 Tutorial Conflicting behavior with WeakValueDictionary.
Jesse Bacon added the comment: After further testing it appears that the bug is in IPython not Python 2.7. The bug has been moved to the Python list at https://github.com/ipython/ipython/issues/8403#issuecomment-98565759 -- resolution: - third party status: open - closed ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue24123 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
