[docs] [issue15412] Note in documentation for weakrefs

Antoine Pitrou report at bugs.python.org
Sat Jul 21 12:59:29 CEST 2012

Antoine Pitrou <pitrou at free.fr> added the comment:

> I had assumed that since dead weakrefs were unhashable you couldn't
> safely use them as keys in a dict.  (Presumably removal of a no longer
> hashable key from a dict is O(n)?)

They are unhashable if you didn't hash them alive. Otherwise they retain
their old hash value (which is quite useful :-)).


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