slice object unpickable

Sebastien de Menten sdementen at hotmail.com
Tue Nov 2 11:29:15 CET 2004


Hi,

I wonder why the slice object is not pickable via pickle or cPickle.
E.g.:

import pickle
pickle.dumps(slice(0,4))

leads to

Traceback (most recent call last):
  File "<stdin>", line 1, in ?
  File "/usr/lib/python2.3/pickle.py", line 1386, in dumps
    Pickler(file, protocol, bin).dump(obj)
  File "/usr/lib/python2.3/pickle.py", line 231, in dump
    self.save(obj)
  File "/usr/lib/python2.3/pickle.py", line 313, in save
    rv = reduce(self.proto)
  File "/usr/lib/python2.3/copy_reg.py", line 69, in _reduce_ex
    raise TypeError, "can't pickle %s objects" % base.__name__
TypeError: can't pickle slice objects

Is it an omission ? Am I missing something non trivial that would
impede slices to be pickable ?

My main goal is to pickle an object with some slices as attributes. As
my object is quite simple, I would like to enjoy the automatic pickle
system (i.e. not rewrite a __getstate__, __setstate__, etc).
Is there an easy workaround to the "unpickableness" of slices ? I
tried subclassing slices but it is not allowed.

Thanks for your help.

Seb



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