add list of how to install multiple Python versions

[niccokunzmann]

This links to tutorials about how to install different Python versions alongside eachother.

Contributes to https://github.com/tox-dev/tox/issues/2453#issuecomment-1192927363

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[niccokunzmann]

@gaborbernat thanks for taking your time and also for maintaining tox! I will not say that you have to maintain it - you can reject it - but I would like to clarify my reasoning:

1. I develop Python for 17 years now and just now came across the need to install all required Python versions for testing with tox. That means: I am able to create this pull request and there is a need.
2. In that situation: hundreds of projects use tox, should there be 100 such documentations or one?
3. When I follow the install guide, I would usually (lazy/beginner) not install all Python versions for testing and just go with what I have. To successfully use tox, I should however install all Python versions required not just skip them. This change points into the right direction by putting the work on the community to guide and not the single developer.
4. tox is incomplete to use without the versions of Python necessary.

I know, a tutorial list does not sound appealing. I think, it should be somewhere though. But where?

[gaborbernat]

Just to clarify, I'm not saying we shouldn't do this, I'm just not 100% on this so I'd like the opinions of other maintainers to swing the pendulum one way or another :+1:

[asottile]

I don't think this has a place in tox's docs -- and it's trivial for someone to search the Internet to find how to install python

-1 for me

[gaborbernat]

As Anthony also shares my concerns I decided to not add this part of tox 3. That being said tox 4 documentation will be constructed more along the lines of the https://diataxis.fr/ where I can see this happen within a tutorial.

[gaborbernat]

Thanks for your contribution and sorry this did not get merged but we'll reuse it for tox 4 :-)

[niccokunzmann]

Thanks and great! Ping me when it is happening!

[brunolnetto]

I like how we found a consensus on the issue. I bring one argument to the table: docker install script (available on https://get.docker.com/) manages multiple installations by ad-hoc infer procedure. Take a look at their functions. An alternative pathway is to do some tinkering and extract these OS-sniffer out of the script.

Luckily I managed to do it myself for fun. You may not trust my efforts, of course.

https://github.com/whosbash/shovel/blob/main/scripts/shell/os-utils.sh