[Python-3000] Simplifying pickle for Py3k

[Georg Brandl]

Neil Schemenauer schrieb:
> I guess the library overhaul hasn't really started it but it would
> be nice if the pickle module could get some work.  Today I'm trying
> to efficiently store a class using pickle and the documentation is
> making my head hurt.  I don't think the documentation itself is the
> problem, just the fact that the rules are so complicated.
> 
> I guess there are several different solutions:
> 
>     * Remove backwards compatible stuff from the code and the
>       documentation.  The downside is that old pickles could not be
>       loaded.  Perhaps that's not a huge issue since the removal of
>       old-style classes might already break old pickles.
> 
>     * Remove the backwards compatible stuff from the documentation
>       only.  The would help people using the language but would
>       still be a long term maintenance issue.
> 
>     * Leave the old code in but generate warnings when old pickle
>       mechanisms are used.  Eventually the old stuff could be
>       removed from the code.
> 
>     * Provide an "oldpickle" module the supports pre-3k pickles.
> 
> I think I like the warnings idea best.

I'm in favor of #1, perhaps combined with #4. With the fundamental
change in basic types (unicode -> str, str -> bytes) I wouldn't
expect 2.x pickles to be loadable by 3.0 anyway.

Cruft removal from the pickle protocol is really needed; I don't envy
everyone reading the pickle docs trying to understand which method
exactly he has to implement, which is going to be called with what
arguments, etc.

Georg

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