WeakValueDictionary

Bryan belred1 at yahoo.com
Sun Oct 3 06:11:37 CEST 2004


Bryan wrote:
> there must be something i don't understand about WeakKeyDictionary and 
> WeakValueDictionary.  i had expected the last line to be empty because i 
> thought i deleted the last strong reference to variable "a". what am i 
> misunderstanding?
> 
>  >>> d = weakref.WeakValueDictionary()
>  >>> a = A()
>  >>> d[1] = a
>  >>> d.items()
> [(1, <__main__.A instance at 0x0116BC60>)]
>  >>> del a
>  >>> d.items()
> [(1, <__main__.A instance at 0x0116BC60>)]
>  >>>
> 
> thanks,
> 
> bryan


i have another question about weak references.   how do you know that b is dead?


 >>> a = A()
 >>> b = weakref.ref(a)
 >>> b
<weakref at 011739F0; to 'instance' at 01135CB0>
 >>> del a
 >>> b
<weakref at 011739F0; dead>



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