Re: MBF for deprecating Python2 usage
barry@debian.org writes:
> On Aug 3, 2017, at 23:23, Scott Kitterman <debian@kitterman.com> wrote:
> You’re right that folks will still need Python 2 after 2020, and that
> their best option may be to build it themselves, but I don’t think
> they’ll be building and installing some old Debian package. Instead
> they may build from source, which means they’ll be installing it into
> /usr/local/bin not /usr/bin, and they’ll have to change their shebang
> lines anyway.
It is very usual to use "#!/usr/bin/env python" as shebang, exactly for
the case that python is not installed in /usr/bin.
>> Such a change would be actively user hostile.
>>
>> When python2.7 goes away, /usr/bin/python should go too.
>
> Maybe in the short term (as Matthias suggests), but I’m not so sure
> it’s best to disappear /usr/bin/python forever. /usr/bin/python is
> not just the common shebang (and we should be actively transitioning
> to /usr/bin/python2 for that), but it’s also the command line UI for
> people wanting to learn Python, or just wanting to get an interactive
> interpreter to play with.
That is -- at least in my environmet -- "ipython", or (for Python 3)
"ipython3".
> There will be a day when, if they get a command not found when typing
> `python` at a shell prompt, they will wonder why Debian is broken.
IMO it would be better to communicate that the best way for an
interactive session is "ipython3" (or "python3", if you insist). I would
wonder when todays tutorials (that cover Python 3) recommend to use
plain "python".
> I think the transition should roughly be:
>
> * Update policy and tooling so that any scripts that require Python 2
> use /usr/bin/python2 in their shebang.
>
> * Educate our users that they should be using `python2` for anything
> that has not been ported.
>
> * Port as much as possible to Python 3 (eventually, everything
> maintained in Debian) and /usr/bin/python3 in their shebang.
I disagree here, and I don't see an advantage over letting
/usr/bin/python just die with Python 2.
I would also like to point PEP 394, which has a number of arguments why
/usr/bin/python should remain as Python 2.
https://www.python.org/dev/peps/pep-0394/
Best regards
Ole
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