[pypy-dev] python 3

[Alex Gaynor]

On Tue, Aug 16, 2011 at 5:39 PM, Benjamin Peterson <benjamin at python.org>wrote:

> 2011/8/16 Yury Selivanov <yselivanov.ml at gmail.com>:
> > Is it possible for pypy core developers to create a high-level roadmap
> with what needs to be done and where?  Should python3 be another translation
> target?  Will it be required to touch rpython spec?  What data structures
> need to be introduced?  etc.  I don't think this planning will take weeks of
> work, but it will help everyone to understand how much time and money should
> be invested in the matter.
>
> First of all, there are some rather large decisions to be made:
>
> 1. Port everything (Python interpreter, RPython) over to Python 3 and
> only support Python 3. This would probably be the cleanest and easiest
> in the longterm solution, but I doubt many are willing to accept it
> quite yet.
>
> 2. Somehow maintain Python 2 and 3 in the same codebase. It sounds
> like a hideous mess to me. (I'm happy to be proven wrong.)
>
> 3. Maintain a Python 3 interpreter in a separate repo or branch. This
> is probably the best compromise, but it requires the constant
> maintenance of someone merging the current head work.
>
> Then someone has to buckle down and do the actual porting. Depending
> on the option selected above, the amount of work will vary from huge
> to colossal. If you pick option 2, you have to figure out how to test
> both versions. I imagine there will be quite a tangled mess with
> unicode.
>
> At any rate, some of the initial steps which are compatible with
> Python 2 such as removing tuple unpacking and normalizing raise
> statements can now be taken. They might even make the codebase a bit
> cleaner.
>
>
>
> --
> Regards,
> Benjamin
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>

Personally I think #3 is the only sane path.  We *need* a Python 2 VM for
the forseeable future.  We're pretty lucky in that the JIT, GC, and all the
honest to god complex code is totally seperate from the VM, so just
supporting 2 Python VMs is kind of easy (compared to maintaing 2 JITs or
something).

Alex

-- 
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"The people's good is the highest law." -- Cicero
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