[New-bugs-announce] [issue3635] pickle.dumps cannot save instance of dict-derived class that overrides __getattribute__

[Michael Yang]

New submission from Michael Yang <yangofzeal at gmail.com>:

# pickle.dumps is not able to process an instance of
# a class that inherits from 'dict' and
# overrides the built-in __getattribute__ method
# but can successfully process one that 
# overrides the__getattr__ method

>>> class Examp1(dict):
...   def __getattr__(self,name):
...     return self[name]
... 
>>> class Examp2(dict):
...   def __getattribute__(self,name):
...     return self[name]
... 
>>> ex1 = Examp1()
>>> ex2 = Examp2()
>>> ex1['aKey'] = (3,4)
>>> ex2['aKey2'] = (4,5)
>>> ex1
{'aKey': (3, 4)}
>>> ex1.aKey
(3, 4)
>>> ex2
{'aKey2': (4, 5)}
>>> ex2.aKey2
(4, 5)
>>> import pickle
>>> pickle.dumps(ex1)
b'\x80\x03c__main__\nexamp1\nq\x00)\x81q\x01X\x04\x00\x00\x00aKeyq\x02K\x03K\x04\x86q\x03s}q\x04b.'
>>> pickle.dumps(ex2)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "[hidden]/python3/3.0b2/common/lib/python3.0/pickle.py", line
1319, in dumps
    Pickler(f, protocol).dump(obj)
  File "<stdin>", line 3, in __getattribute__
KeyError: '__reduce_ex__'

----------
components: Extension Modules
messages: 71671
nosy: msyang
severity: normal
status: open
title: pickle.dumps cannot save instance of dict-derived class that overrides __getattribute__
type: behavior
versions: Python 2.5, Python 3.0

_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue3635>
_______________________________________