What to do in 2020 - Python 2 EOL

[felixdivo]

Being the last of the 2.x series, 2.7 will have an extended period of maintenance. Specifically, 2.7 will receive bugfix support until January 1, 2020. After the last release, 2.7 will receive no support.

It's no secret that Python 2 is reaching its end of life.

What do we do from then on? Should we just document which version was the last to support Python 2 + 3 and then do a (possibly incremental) cleanup of the code and only support Python 3 from then on? We could do that in a major version bump (like maybe 4.0).

I would vote for exactly that. Do we all agree on that?

[felixdivo]

cc @hardbyte @christiansandberg

[hardbyte]

Yeah I'm in favor of making a python-can v3.2 release be the final release supporting python2 (with possible bug fixes accepted to a 3.x up until python 2 EOL), that frees us up to do a major version bump to v4 where we could drop python2 support and possibly introduce type annotations throughout the core.

[felixdivo]

Adding typing sounds great indeed! This works especially well because Python 3.4 will reach EOL 2019-03-16. So we would support Python 3.5+ only, which enables us to freely use the typing module.

But we cannot use the "new" typing syntax yet, since it is only supported by Python 3.6+, which will be supported until 2020-09-13.

[danielhrisca]

Why not jump straight to Python >= 3.6?

[felixdivo]

Why not jump straight to Python >= 3.6?

Because Python 3.5 is supported until 2020-09-13.

[hardbyte]

That doesn't mean we have to support Python3.5 in python-can v4. Any Python3.5 users can always use python-can<=3.2.

I work on another codebase using comment based typing and it is a bit of a pain so I'd prefer to make the jump to the new typing syntax.

[danielhrisca]

I think Python 3.6 brings some compelling features: f-strings, ordered dicts with better performance, annotations, improved asyncio

[felixdivo]

Okay, you two convinced me. The users on "archaic" systems may still stay on 2.3.x 👌

[felixdivo]

This can be closed once #594, #595, #596 and #597 are merged.

We should probably open new issues for

some compelling features: f-strings, ordered dicts with better performance, annotations, improved asyncio

[christiansandberg]

Sorry for reopening this but I felt like the drop of support for Python 3.5 could be discussed a little further before going all in on 3.6+. We should consider that the current Debian stable as well as Raspbian only have 3.5. Corporate environments are also usually slow to adapt new versions unless they need to. That is probably going to leave a major user base out that need bug fixes and new features. It might end up with forks or maintenance branches. Are the nice-to-have features like f-strings and new variable typing (what else?) really so important that it makes it worth it?