Weakref proxy missing pass throughs for hash() and reversed() #84703

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1. rhettinger commented on May 5, 2020

   

   rhettinger

   on May 5, 2020

   ContributorAuthor

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   from weakref import proxy
   
   class Alpha:
       def __len__(self):
           return 3
       def __reversed__(self):
           return iter('cba')
       def __hash__(self):
           return hash('abc')
   
   a = Alpha()
   
   # Direct use of the instance works
   print(len(a))
   print(list(reversed(a)))
   print(hash(a))
   
   # Proxies can use the dunder methods directly
   r = proxy(a)
   print(r.__len__())
   print(list(r.__reversed__()))
   print(r.__hash__())

   # Proxy fails for __reversed__ and __hash__
   print(len(r), 'This succeeds')
   try:
   print(list(reversed(r)))
   except TypeError:
   print('reverse(r) failed')
   try:
   print(hash(r))
   except TypeError:
   print('hash(r) failed')
2. rhettinger

   added

   3.8 (EOL)end of lifeend of life

   3.9 (EOL)end of lifeend of life

   stdlibStandard Library Python modules in the Lib/ directoryStandard Library Python modules in the Lib/ directory

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   on May 5, 2020
3. pablogsal commented on May 5, 2020

   

   pablogsal

   on May 5, 2020

   Member

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   New changeset 96074de by Pablo Galindo in branch 'master':
   bpo-40523: Add pass-throughs for hash() and reversed() to weakref.proxy objects (GH-19946)
   96074de
4. pablogsal

   closed this as completedon May 5, 2020
5. pablogsal

   closed this as completedon May 5, 2020
6. ezio-melotti

   transferred this issue fromon Apr 10, 2022