RFC: Setting a minimum Python version of 3.4 [Was: Future of Python 2 compat code in python-debian]

[Stuart Prescott]

Hi again

My previous request for comment (reproduced below to save you searching) 
didn't elucidate any responses, so I'll have another attempt at provoking a 
response here...

I propose that:

* we raise the minimum Python version needed for python-debian to Python 3.5 
(which was available in stretch/oldstable)

* we drop compat code for Python 2.7 and older Python 3.2/3.3/3.4 as we go 
(that includes typing, enum, and various workarounds for decompressors; 
there's about 20 places in the code where the version of the interpreter is 
tested, all of which could go). This doesn't need to be done in a rush.

* we continue to run tests on both stable and unstable with all supported 
Python 3 interpreters (`py3versions -s`)

comments, thoughts, reactions?

regards
Stuart


On Sunday, 12 April 2020 13:14:18 AEDT Stuart Prescott wrote:
> Hi folks
> 
> As you might have just noticed, we have now dropped the Python 2 module
> package (python-debian) from the archive. I've not yet disabled running the
> test suite under Python 2 on salsa.
> 
> The question is then what to do with Python 2 support and indeed also code
> that exists to work around limitations in Python 3.3 and 3.4.
> 
> We can do one of the following:
> 
> 1) Continue to support python >= 2.7 and python3 >= 3.3. Leave the Python 2
> and 3.old code in there for the time being and leave the test suite running
> under Python 2 for as long as possible. However, the tests are run against
> Debian unstable and python-apt will soon be unavailable there.
> 
> 2) Continue to support python >= 2.7 and python3 >= 3.3. Leave the Python 2
> and 3.old code there with disabled tests and when it breaks, shrug our
> shoulders
> 
> 3) Declare support for python3 >= 3.5. Disable tests but only remove the
> legacy support whenever someone is spending time on a particular piece of
> code
> 
> 4) Declare support for python3 >= 3.5. Actively remove old code now.
> 
> Thinking about releases we support, python3 in stretch and all supported
> Ubuntu releases is >= 3.5. Any backported packages that needed a newer
> python- debian for some reason would also be using python3 >= 3.5 at this
> stage.
> 
> I am personally leaning towards 3 or 4.
> 
> Comments and suggestions most welcome.
> 
> Stuart


-- 
Stuart Prescott    http://www.nanonanonano.net/   stuart at nanonanonano.net
Debian Developer   http://www.debian.org/         stuart at debian.org
GPG fingerprint    90E2 D2C1 AD14 6A1B 7EBB 891D BBC1 7EBB 1396 F2F7