[Python-3000] Simplifying pickle for Py3k

[Guido van Rossum]

I think it's essential to be able to *read* pickles generated by older
Python versions. But for writing I'm okay with only writing protocol 2
(which Python 2.x also understands) and only supporting the modern
APIs for customizing pickle writing.

I don't think classic class instances are necessarily unpicklable in
3.0 -- they will just show up as instances of the corresponding
new-style classes.

--Guido

On 10/3/07, Neil Schemenauer <nas at arctrix.com> wrote:
> 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.
>
>   Neil
>
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-- 
--Guido van Rossum (home page: http://www.python.org/~guido/)