[issue24123] Python 2.7 Tutorial Conflicting behavior with WeakValueDictionary.
Jesse Bacon
report at bugs.python.org
Mon May 4 01:17:56 CEST 2015
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
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