[LyX/ next] Prepare the removal of Python 2 support

[Jean-Marc Lasgouttes]

Le 30/05/2024 à 17:58, José Matos a écrit :
> In order to pay the technical debt that is the Python 2 support I
> intend to start removing its support.
> 
> The first step is to change the build support to ignore Python 2.
> 
> Since that is code that, usually, I run away from I would like to get
> your feedback before committing it. Because if this breaks the package
> does not build and that is a huge problem. :-)
> 
> @Jean-Marc is the code OK for the autotools?

I'd suggest AM_PATH_PYTHON now that we do not have 2 versions anymore.
https://www.gnu.org/software/automake/manual/html_node/Python.html

> There is another change that deserves to be discussed, in the process I
> have bumped the minimum python version to be 3.10.
> 
> Assuming that the next development cycle takes 2.5 years this will be a
> version that will be 5 years old by then and so it should be widely
> available.

I am doubtful about this one. I would think some Ubuntu LTS versions 
without 3.10 will still be supported.

> In this particular case the reason to jump directly to 3.10 is the
> structural pattern matching:
> 
> https://docs.python.org/3/whatsnew/3.10.html#pep-634-structural-pattern-matching
> 
> FWIW notice that this is a lot more powerful than the usual C/C++
> switch.
> I think that some of our code, like lyx2lyx, can take direct advantage
> of this feature.

I get the point.

JMarc