Hi,

To help with people who want to make an informed decision, is there
any public discussion of the original NEP 29 proposal?

The only thing I could find was this post from Sebastian Berg, where he says at

https://mail.python.org/pipermail/numpy-discussion/2019-October/080128.html

"We propose formally accepting the NumPy enhancement proposal 29... If
there are no objections within a week it may be accepted.".
There's no public voting or anything, and there's exactly one quick
random response of "yes" in the thread.

In the actual NEP 29 proposal
https://numpy.org/neps/nep-0029-deprecation_policy.html there is a
section labeled "Discussion" and it is empty.
I would love to read about the discussions for/against NEP 29 from
when they decided on it in the first place!

There are follow up discussions, just like this one, by other
projects, e.g., for sympy here:
https://github.com/sympy/sympy/issues/21884, which
is still not decided, and has been under regular discussion for nearly
2 years.  There are many other similar conversations.  But they are
all about whether to align with numpy or not, and the core question of
why it is best to ignore what the official upstream python supports
isn't as relevant.

The original NEP 29 says "The Python release cadence increased in PEP
0602, [...] Thus, we do not expect our users to upgrade Python faster,
and our 42 month support window will cover the same portion of the
upstream support of any given Python release."    I don't really know
what that means, but I have the impression that NEP 29 tried to very
rigidly define end of life by a specific timeline with no flexibility
for the potential that the official Python release timelines are not
rigid and fixed in stone forever, while simultaneously acknowledging
this conflict.  I would love to see the arguments for doing that,
which could be compelling.   I fully realize that this is something
that came from maintainers of open source software, and they were
probably feeling annoyed and burned out, and this NEP 29 may have
helped them keep their sanity.  But if that's the case, it's decided
in secret as far as I can tell.

 -- William

On Fri, May 26, 2023 at 6:34 AM Matthias Koeppe
<matthiaskoe...@gmail.com> wrote:
>
> Thanks, Tobias, for opening this vote thread. Here on sage-devel, this is a 
> much better setting than what you attempted in 
> https://github.com/sagemath/sage/pull/35404#issuecomment-1504474945
>
> I am voting NO.
>
> There's a simple rationale:
>
> I. This proposed policy change does not solve any problem. There are no 
> problems whatsoever with how we have managed the support of Python versions 
> since 2020 (when it became possible to use system Python instead of only the 
> Python from our SPKG.)
>
> II. The proposed policy change creates new problems. Following this policy 
> would force us to drop support for a particular Python version at times when 
> it would be harmful for our project. Specifically, right now it would *force* 
> us to drop support for Python 3.8 and hence for using the default Python on 
> Ubuntu Linux 20.04 (an LTS release, with "End of Standard Support" April 2025 
> and "End Of Life" April 2030. It is the very point of LTS releases to provide 
> a stable software environment; so, yes, Python 3.8 is fully supported, and if 
> Python 3.8.x had bugs relevant for Sage, we would know about it because we 
> are testing.
>
> III. Our existing practice is to carefully consider and weigh various factors 
> that are relevant for the Sage project, rather than following a fixed 
> schedule that is set by an external, largely separate community. I briefly 
> explained what we do in 
> https://groups.google.com/g/sage-devel/c/j1cwbTU8aOU/m/x3qOdPB5BQAJ; but I'll 
> expand here on some important factors:
>
> a) Sage has a dual role as a library ("project") and as a distribution. NEP 
> 29 was designed for projects, and not for software distributions.
>
> b) In Sage, we only have one line of releases. Hence users who want any bug 
> fixes need to use our latest version. In contrast, just like Python itself, 
> many other projects have at least two separate branches: A branch on which 
> the cutting edge development takes place (new features etc.), and a branch 
> from which maintenance updates are made. For example, NumPy removed support 
> of Python 3.8 in their development branch earlier this year; but this in 
> preparation for the 1.25 release expected this summer. NumPy continued to 
> make maintenance releases on the 1.24 branch 
> (https://github.com/numpy/numpy/releases), and by policy, these maintenance 
> upgrades never drop the support of a previously supported version.
>
> c) NEP29 was designed for and is in use by a part of the scientific Python 
> community, to address the need to be able to use features of new Python 
> versions and features of NumPy/SciPy faster. This is important for many 
> projects that have NumPy/SciPy as their dependencies.
>
> d) In contrast, our uses of NumPy/SciPy in the Sage library are very basic 
> and dating back by about a decade; with the exception of the optional use of 
> a recent SciPy feature (the high-performance optimization solver HiGHS, see 
> https://github.com/sagemath/sage/wiki/Sage-10.0-Release-Tour#linear-programming-and-extensions),
>  which motivated our quick upgrade to the current SciPy version in Sage. And 
> as another example, also our use of matplotlib in the library dates back by a 
> decade or more; we regularly have to update when new matplotlib versions come 
> out that make API changes, but we haven't picked up any new features in a 
> very long time.
>
> e) Yes, synchronization between projects matters for maintainability. But 
> Sage is downstream of lots of Python packages; before we can offer support 
> for a new version of Python, we often have to wait until all or most of our 
> dependencies provide support for that new version. For example, some projects 
> are actively working on support for the Python 3.12 release expected this 
> early Fall; but for us, this is not actionable because we have to wait for 
> critical dependencies; see https://github.com/sagemath/sage/issues/34788 . 
> Likewise, it is not useful for us to drop support for an old version before 
> there is a clear benefit for us, brought for example by important upgrades 
> that have dropped support already.
>
>
> (As suggested by Tobias, any discussion of my explanations above is best sent 
> to the https://groups.google.com/g/sage-devel/c/j1cwbTU8aOU/m/2sTiwdKPBQAJ 
> thread.)
>
>
> On Friday, May 26, 2023 at 3:12:16 AM UTC-7 Tobias Diez wrote:
>>
>> Dear Sage developers,
>>
>> the NumPy enhancement proposal 29: "Recommend Python and Numpy version 
>> support as a community policy standard" (available at 
>> https://numpy.org/neps/nep-0029-deprecation_policy.html) specifies when it's 
>> okay to drop support for old Python version.
>>
>> Namely, a release should support "all minor versions of Python released 42 
>> months prior to the project, and at minimum the two latest minor versions. 
>> ". In particular, this means:
>> - Currently, Sage should support > 3.8.
>> - On Apr 05, 2024 we should drop support for Python 3.9 (initially released 
>> on Oct 05, 2020)
>>
>> Based on previous discussions on this topic 
>> (https://groups.google.com/g/sage-devel/c/j1cwbTU8aOU/m/2sTiwdKPBQAJ, 
>> https://github.com/sagemath/sage/issues/30384, 
>> https://github.com/sagemath/sage/pull/35403), I'm calling for a vote on 
>> adapting the Python version support of NEP 29 in Sage. Voting ends at the 
>> 7th June,  AoE. Please use this thread only for sending votes, to make it 
>> easier to count them afterward; and use the thread 
>> https://groups.google.com/g/sage-devel/c/j1cwbTU8aOU/m/2sTiwdKPBQAJ for 
>> discussion.
>>
>> Summary of the points brought forward in the discussions linked above
>> 1. The current practice in Sage is to evaluate whether to increase the 
>> minimum version of Python supported at the beginning of each release cycle. 
>> With regard to such a practice, the NEP 29 documents remarks "As there is no 
>> objective threshold to when the minimum version should be dropped, it is 
>> easy for these version support discussions to devolve into bike shedding and 
>> acrimony." Sadly, an example of this can be found in the current discussion 
>> of dropping Python 3.8 support in 
>> https://github.com/sagemath/sage/pull/35404 with emotions running so high 
>> that sage-abuse had to step in. Adopting a version policy would prevent such 
>> discussions. On the other hand, by following a given policy, we would loose 
>> some flexibility.
>> 2. The main idea of NEP 29 is to have a community-wide standard. It is 
>> followed by many scientific packages such as Scipy, Matplotlib, IPython, 
>> Jupyter, Pandas, scikit, astropy, cuda, cirq, jax, pytorch among others. The 
>> adoption of NEP 29 will harmonize Sage's deprecation policy with these other 
>> major libraries.
>> 3. The NEP 29 drop schedule is much faster than the EOL schedule of Python 
>> itself. Python 3.8 is supported until 2024-10, but NEP 29 already drops it 
>> 2023-04. However, adhering to the EOL schedule would prevent us to updating 
>> these packages that follow NEP 29.
>> 4. The NEP 29 schedule is about one release cycle faster than the previous 
>> drops (e.g. Python 3.7 support was dropped in Sage 9.7 while according to 
>> NEP 29 it would have been Sage 9.6).
>> 5. The faster drop schedule will free developer resources (less systems to 
>> test) and potentially increase developer productivity as it allows us to use 
>> newer language features.
>> 6. The faster drop schedule might be inconvenient for users who rely on 
>> older Python versions. To some extend this is remedied by our python install 
>> package, and relatively straightforward upgrade paths on most system. One 
>> should also note that users relying on other scientific python packages are 
>> likely forced to upgrade anyway, since these other packages likely follow 
>> NEP 29.
>> 7. The faster drop schedule would force users to upgrade to newer Python 
>> versions and thereby profit from fewer bugs and security issues. It is 
>> however questionable if Sage should play this educator role.
>> 8. One of the main goals of NEP 29 is to improve downstream project planning 
>> by having a community-wide standard. This is currently not very relevant for 
>> us as Sage is currently upstream of nothing except for some user packages. 
>> With the modularization effort, this may change in the future.
>> 9. There are not many other documented policies. As said above, most 
>> scientific python projects follow NEP 29. Most projects in web development 
>> (e.g flask) seem to drop a version once it reaches EOL. Machine learning 
>> projects follow a similar EOL policy (e.g. tensorflow) or roughly follow NEP 
>> 29 (scikit-learn). Some end-user applications have even stricter version 
>> constraints then NEP 29 (e.g. home-assistant only supports the two latest 
>> minor releases).
>>
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-- 
William (http://wstein.org)

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