[Tutor] portability of pickle and shelve across platforms and different python versions?

[Bjorn Egil Ludvigsen]

I do not know all the details, but I think it is NOT portable.

The reason I am saying this is from a comment in Mark Summerfields excellent
book "Rapid GUI programming with Python and Qt" where he has an example that
uses several different load/save methods (chapter 8). He recommends using
Qt's QDataStream method to write/read binary fields over pickle/cpickle
because the Qt method is fully platform independent and it can handle Qt
classes more effortlessly.

He writes that files written with QDataStream are platform-independent; the
class automatically takes care of endianess and word size. Since he does not
say this about pickle I infer from this that files written by pickle does
not take care of endianess or word size automatically.

Sorry for the guesswork as I might be wrong, but I hope this will guide you
in the right direction or that others will come up with more correct
answers.

Regards,
Bjorn

On Wed, May 5, 2010 at 6:12 PM, Garry Willgoose <
garry.willgoose at newcastle.edu.au> wrote:

> I have seen conflicting info on this on the web and in the tutor archive
> and the docs don't seem to address it explicitly. How portable are files
> containing pickle'd and shelve'd data? I'm thinking issues like simply O/S
> portability, through big-end/little-end hardware (for floats/integers which
> I use a lot), and then for unicode/non-unicode string,  64/32 bit and
> V2.6/V3.1 implementations of python. Does the version of the encoder in
> pickle make any difference for this? One post I've seen suggests that as
> long as the file is opened binary (ie. 'b') all should be well for platform
> independence.
>
> My core question if I give a pickled file to somebody else can i guarantee
> they can read/load it OK. The other person will be using exactly the same
> python code to open it as used to create it.
>
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