weird pickle behavior in Python 3.1.2 + Eclipse 3.5.2

[kirby.urner at gmail.com]

On Jun 4, 9:47 am, Peter Otten <__pete... at web.de> wrote:

> I can provoke the error in "naked" Python 3 by changing the
> Example.__module__ attribute:
>
> Python 3.1.1+ (r311:74480, Nov  2 2009, 15:45:00)
> [GCC 4.4.1] on linux2
> Type "help", "copyright", "credits" or "license" for more information.

> >>> import pickle
> >>> class Example:
>
> ...     pass
> ...
> >>> pickle.dumps(Example())
>
> b'\x80\x03c__main__\nExample\nq\x00)\x81q\x01}q\x02b.'

> >>> Example.__module__ = "builtins"
> >>> pickle.dumps(Example())
>
> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
>   File "/usr/lib/python3.1/pickle.py", line 1358, in dumps
>     Pickler(f, protocol, fix_imports=fix_imports).dump(obj)
> _pickle.PicklingError: Can't pickle <class 'Example'>: attribute lookup
> builtins.Example failed
>
> What's the value of __module__ when you run your code in Eclipse?
>
> Peter

Thank you for replying.

Here's from Eclipse console:

>>> Example.__module__
'builtins'

>>> __name__
'builtins'

Duplicating your result in naked Python:

Python 3.1.2 (r312:79149, Mar 21 2010, 00:41:52) [MSC v.1500 32 bit
(Intel)] on win32
Type "copyright", "credits" or "license()" for more information.
>>> class Example:
	pass

>>> import pickle
>>> Example.__module__
'__main__'
>>> f = open('testpickle.pkl','wb')
>>> obj = Example()
>>> obj
<__main__.Example object at 0x02A26690>
>>> pickle.dump(obj, f)

>>> Example.__module__ = 'builtins'
>>> obj2 = Example()

>>> pickle.dump(obj2, f)
Traceback (most recent call last):
  File "<pyshell#12>", line 1, in <module>
    pickle.dump(obj2, f)
  File "C:\Python31\lib\pickle.py", line 1354, in dump
    Pickler(file, protocol, fix_imports=fix_imports).dump(obj)
_pickle.PicklingError: Can't pickle <class 'Example'>: attribute
lookup builtins.Example failed

So what if I'm in an Eclipse pydev console and
change the Example.__module__ to '__main__'....

>>> import sys; print('%s %s' % (sys.executable or sys.platform, sys.version))
C:\Python31\python.exe 3.1.2 (r312:79149, Mar 21 2010, 00:41:52) [MSC
v.1500 32 bit (Intel)]
>>> import pickle
>>> class Example:
...     pass
...
>>> Example.__module__
'builtins'
>>> Example.__module__ = '__main__'
>>> obj = Example()
>>> obj
<__main__.Example object at 0x029E8FD0>
>>> f = open('testpickle.pkl','wb')
>>> pickle.dump(obj, f)
Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "C:\Python31\lib\pickle.py", line 1354, in dump
    Pickler(file, protocol, fix_imports=fix_imports).dump(obj)
_pickle.PicklingError: Can't pickle <class '__main__.Example'>:
attribute lookup __main__.Example failed
>>>

Dang.

Any insights?

Kirby