En Fri, 06 Mar 2009 19:56:07 -0200, Sebastian Bartos
<seth.kriti...@googlemail.com> escribió:
I have a question. I'm writing a simple object serialization module
using shelve to write arbitrary objects to a file (M.py). Now I have the
problem, that if I create a simple object in the doctest documentation
file M.txt like this:
>>> class tdata(object):
... def __init__(self, name):
... self.name = name
>>> tinst = tdata(u'foo')
and then run it with my module M:
>>> import M
>>> foo = M.serialize('/tmp/foo', tinst.name, tinst)
then I get the following problem:
Failed example:
foo = M.serialize('/tmp/foo', tinst)
Exception raised:
Traceback (most recent call last):
File "/usr/lib/python2.5/doctest.py", line 1228, in __run
compileflags, 1) in test.globs
...
File "/usr/lib/python2.5/shelve.py", line 123, in __setitem__
p.dump(value)
PicklingError: Can't pickle <class 'tdata'>: attribute lookup
__builtin__.tdata failed
If I do the same in the interactive interpreter, then it works fine.
Now, as I want to test an arbitrary data class, the doctest file is the
place to put the simple tdata class, but as far as I traced the problem,
it uses it's own namespace or something, and so does not work.
The environment in which doctests run isn't a module, and pickle requires
that the class definition be a top level object in a module. So your class
should reside in a true Python module.
In your case, if the intent was to show that any class may be serialized
using your library, I think you could use *any* existing class in any
other module - there is no need to create a special one.
This is a (very ugly!) workaround:
>>> def _register_as_true_class_in_its_module(class_):
... import sys
... m = sys.modules[class_.__module__]
... setattr(m, class_.__name__, class_)
...
>>> class tdata(object):
... def __init__(self, name):
... self.name = name
>>> _register_as_true_class_in_its_module(tdata)
>>> tinst = tdata(u'foo')
See http://bugs.python.org/issue5021 for a (somewhat) related issue.
--
Gabriel Genellina
--
http://mail.python.org/mailman/listinfo/python-list
