[Numpy-discussion] Proposal of timeline for dropping Python 2.7 support

[Petr Viktorin]

On 11/09/2017 12:15 AM, Nathaniel Smith wrote:
> On Nov 8, 2017 16:51, "Matthew Brett" <matthew.brett at gmail.com 
> <mailto:matthew.brett at gmail.com>> wrote:
> 
>     Hi,
> 
>     On Wed, Nov 8, 2017 at 7:08 PM, Julian Taylor
>     <jtaylor.debian at googlemail.com
>     <mailto:jtaylor.debian at googlemail.com>> wrote:
>      > On 06.11.2017 11:10, Ralf Gommers wrote:
>      >>
>      >>
>      >> On Mon, Nov 6, 2017 at 7:25 AM, Charles R Harris
>      >> <charlesr.harris at gmail.com <mailto:charlesr.harris at gmail.com>
>     <mailto:charlesr.harris at gmail.com
>     <mailto:charlesr.harris at gmail.com>>> wrote:
>      >>
>      >>     Hi All,
>      >>
>      >>     Thought I'd toss this out there. I'm tending towards better
>     sooner
>      >>     than later in dropping Python 2.7 support as we are starting
>     to run
>      >>     up against places where we would like to use Python 3
>     features. That
>      >>     is particularly true on Windows where the 2.7 compiler is
>     really old
>      >>     and lacks C99 compatibility.
>      >>
>      >>
>      >> This is probably the most pressing reason to drop 2.7 support.
>     We seem
>      >> to be expending a lot of effort lately on this stuff. I was
>     previously
>      >> advocating being more conservative than the timeline you now
>     propose,
>      >> but this is the pain point that I think gets me over the line.
>      >
>      >
>      > Would dropping python2 support for windows earlier than the other
>      > platforms a reasonable approach?
>      > I am not a big fan of to dropping python2 support before 2020, but I
>      > have no issue with dropping python2 support on windows earlier as
>     it is
>      > our largest pain point.
> 
>     I wonder about this too.  I can imagine there are a reasonable number
>     of people using older Linux distributions on which they cannot upgrade
>     to a recent Python 3,
> 
> 
> My impression is that this is increasingly rare, actually. I believe 
> RHEL is still shipping 2.6 by default,

RHEL 6 does have Python 2.6, but RHEL 6 is in its "security and critical 
fixes only" phase. I would not expect people with Python 2.6 on RHEL 6 
to go and upgrade Numpy to the newest version. (But I admit I might be 
wrong, especially regarding CentOS.)

> which we've already dropped 
> support for, and if you want RH python then they provide supported 2.7 
> and 3.latest through exactly the same channels. 

It might not always be the very latest, but yes, 3.6 is available 
through Software Collections.

Let me know if I can help! I work on Python packaging at Red Hat (though 
on this list I'm subscribed with my personal e-mail).
And feel free to direct people who have trouble running Python 3 on 
RHEL/CentOS to me.

Also, if you haven't read Nick Coghlan's thoughts on these matters, I 
recommend doing that -- they're from 2015 but still relevant. (It's 
targetting projects run entirely by volunteers, which might not entirely 
apply to NumPy, but it still has some good ideas): 
http://www.curiousefficiency.org/posts/2015/04/stop-supporting-python26.html