On Sun, Mar 11, 2018 at 12:10:09PM +0100, Ricardo Wurmus wrote: > Obviously, I strongly disagree :) You should ;)
> On my CentOS and Fedora machines at work both versions are installed > (with the system package manager) and nobody complains. I can conjure > up a Python 2 environment by calling “python2” and a Python 3 > environment by calling “python3” or “python”. Neither variant will load > up modules for the other variant — unlike the behaviour on Guix. > > Even in Guix we allow these packages to be added to the same environment > with “guix environment --ad-hoc” – and there are no collisions, because > upstream made the effort to ensure that these packages don’t provide > files of the same names. > > It is an unnecessary restriction to *prevent* users from installing > Python 2 and 3 interpreters into the same profile. Any errors we see > with mixing 2 and 3 is due to a bug in Guix which is due to our use of > PYTHONPATH. Alright, if you choose to use them as two different tools/languages. But even in minor versions there are problems. Ruby has those too, I know for a fact, though Python may be worse since it uses compiled sources. > In large environments Python 2 and 3 modules and interpreters can > peacefully coexist as long as the tools use the appropriate names for > the interpreters (“python2” or “python” for Python 2, “python3” for > the interpreter for Python 3). > > In other places in Guix we don’t even prevent users from doing things > that are generally ill-advised (e.g. the use of LD_LIBRARY_PATH); why > would we prevent a perfectly valid use-case when it comes to different > versions of Python? Sure. Note that Python2 is quickly becoming obsolete. It is escalating because packages are now dropping support. After 10 years of joy mixing versions... Pj.
