PyPy support breaking CPython compatibility?

[Chris Angelico]

On Wed, Jan 31, 2018 at 6:35 AM, Etienne Robillard <tkadm30 at yandex.com> wrote:
> Hi,
>
> I managed to patch Schevo and Durus to run under PyPy 5.9. However, I'm
> afraid the changes is breaking Python 2.7 compatibility.
>
> I'm not sure how I should distribute my changes to the respective projects.
>
> Since I decided to use more PyPy in my Django projects, should I drop Python
> 2.7 support and release the experimental code on PyPi ?
>
>
> What do you think?

First off, what's your status on Python 3? When you say "PyPy 5.9",
are you referring to the one that's compatible with Python 3.5 or the
one that's compatible with Python 2.7?

If you're supporting Python 3, I don't think there's any problem with
saying "Python 2.7 support ceases as of Schevo v4.0, so if you need Py
2.7 use Schevo 3.x". (It's not as if the old versions will suddenly
cease working or anything.)

On the other hand, if you're looking at two different Python 2.7
interpreters, you'll be narrowing your potential userbase
significantly by dropping CPython support. Maybe that's not an issue
for you (hey, I've "released" code that depends on features in
unreleased versions of Python - the intended userbase is basically
just me, even though the code's open source and published), but it's
definitely a consideration.

ChrisA