Re: [gentoo-user] python, my nemesis

[Michael Orlitzky <mjo@gentoo.org>]

On Mon, 2021-09-20 at 14:50 +0200, Gerrit Kuehn wrote:
> Hi,
> 
> I'd like to update a system that is about 1 year old. I have python3.7
> and python 3.8 installed, 3.7 is the default. After updating the repo,
> it was suggested to update portage first (probably useful to support
> new EAPI versions).
> I read about updating to python 3.9, so I created
> 
> ---
> ~ # cat /etc/portage/package.use/py 
> */* PYTHON_TARGETS: -* python3_9 python3_8
> */* PYTHON_SINGLE_TARGET: -* python3_9
> ---

You should probably not mess with these variables until after your
system is 100% updated and consistent. And even then, probably not.

With our package manager written in python, you often need old python
stuff to build the new python stuff, and disabling the old python stuff
will throw a wrench into that. Even in situations where technically
some upgrade path exists, the complexity of the python dependencies
often means that the package manager will give up before it finds the
solution unless the solution is obvious. By tweaking those variables,
you make the solution less obvious to it.