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

[Chris Barker]

On Fri, Nov 17, 2017 at 4:35 AM, Peter Cock <p.j.a.cock at googlemail.com>
wrote:

> Since Konrad Hinsen no longer follows the NumPy discussion list
> for lack of time, he has not posted here - but he has commented
> about this on Twitter and written up a good blog post:
>
> http://blog.khinsen.net/posts/2017/11/16/a-plea-for-
> stability-in-the-scipy-ecosystem/
>
> In a field where scientific code is expected to last and be developed
> on a timescale of decades, the change of pace with Python 2 and 3
> is harder to handle.
>

sure -- but I do not get what the problem is here!

from his post:

"""
The disappearance of Python 2 will leave much scientific software orphaned,
and many published results irreproducible.
"""

This is an issue we should all be concerned about, and, in fact, the scipy
community has been particularly active in the reproducibility realm.

BUT: that statement makes NO SENSE. dropping Python2 support in numpy (or
any other package) means that newer versions of numpy will not run on py2
-- but if you want to reproduce results, you need to run the code WITH THE
VERSION THAT WAS USED IN THE  FIRST PLACE.

So if someone publishes something based on code written in python2.7 and
numpy 1.13, then it is not helpful for reproducibility at all for numpy
1.18 (or 2.*, or whatever we call it) to run on python2. So there is no
issue here.

Potential issues will arise post 2020, when maybe python2.7 (and numpy
1.13) will no longer run on an up to date OS. But the OS vendors do a
pretty good job of backward compatibility -- so we've got quite a few years
to go on that.

And it will also be important that older versions of packages are available
-- but as long as we don't delete the archives, that should be the case for
a good long while.

So not sure what the problem is here.

note relevant for reproducibility,but I have always been puzzled that folks
often desperately want to run the very latest numpy on an old Python (2.6,
1.5, ....) if you can update your numy, update your darn Python too!

-CHB

-- 

Christopher Barker, Ph.D.
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