Johan Kohler wrote:
> Hi,
> In the attached code, I'm trying to pickle and unpickle
> (1) an object containing a list of dictionaries.
> (2) an object containing a list objects each containing a dictionary.
>
[successful usecase]
>
> but (2) fails with the following error:
>
> <__main__.User instance at 0x41a56fac>
> <__main__.User instance at 0x41a56f2c>
> Traceback (most recent call last):
> File "/usr/lib/python2.3/site-packages/sm/scriptutils.py", line 49,
> in run
> exec codeObject in mainDict
> File "<source>", line 87, in ?
> File "<source>", line 79, in loadbroken
> File "<source>", line 33, in readfromfile
> File "/usr/lib/python2.3/pickle.py", line 1390, in load
> return Unpickler(file).load()
> File "/usr/lib/python2.3/pickle.py", line 872, in load
> dispatch[key](self)
> File "/usr/lib/python2.3/pickle.py", line 1083, in load_inst
> klass = self.find_class(module, name)
> File "/usr/lib/python2.3/pickle.py", line 1140, in find_class
> klass = getattr(mod, name)
> AttributeError: 'module' object has no attribute 'User'
> Exception raised while running script <source>
> ---
>
> I hope this is not a limitation of Pickle, because that would mean I
> have to change a large section of my code :-(
Pickle can handle any object but it needs the definition of the class
of the object to be available in order to unpickle.
For example:
.>>> class A: pass
....
.>>> a = A()
.>>> import pickle
.>>> s = pickle.dumps(a)
.>>> s
'(i__main__\nA\np0\n(dp1\nb.'
.>>> pickle.loads(s)
<__main__.A instance at 0x403fdcec>
.>>> del A
.>>> pickle.loads(s)
Traceback (most recent call last):
File "<stdin>", line 1, in ?
File "/usr/lib/python2.3/pickle.py", line 1394, in loads
return Unpickler(file).load()
File "/usr/lib/python2.3/pickle.py", line 872, in load
dispatch[key](self)
File "/usr/lib/python2.3/pickle.py", line 1083, in load_inst
klass = self.find_class(module, name)
File "/usr/lib/python2.3/pickle.py", line 1140, in find_class
klass = getattr(mod, name)
AttributeError: 'module' object has no attribute 'A'
The tracebacks are similar. It seems class User is not available when
unpickling in the second case.
Javier
PS: I have not actually looked at the code so YMMV. :p
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