On Thu, Jul 22, 2021 at 8:31 PM Shlomo Solomon <shlomo.solo...@gmail.com> wrote: > > OK - to sum up: > 1 - thanks to Omer and Dan > 2 - it seems that I did understand the concept of virtual environments > - as I wrote in my original post: > > I know I can use venv to set up virtual environments for different > > versions, but although I haven't tried it, I don't see how that would > > solve the problem. > 3 - based on the answers you both wrote, there's no solution to the > "problem" of having to re-install modules. > 4 - and it's probably not a good idea to try :-)
That's the main point, not that there is no solution. If you want to try to enforce use of modules from the other version, you can use PYTHONPATH and/or sys.path, or even play with importlib. But it remains a bad idea, unless you have very specific needs - not a mere "trying to save time". Best regards, > 5 - based on all of the above, I'll probably pass on the idea of using > 2 versions and wait for Kubuntu to move to 3.9, which will probably not > be too far in the future. > > Again - thanks > > > > On Thu, 22 Jul 2021 20:07:20 +0300 > Omer Zak <w...@zak.co.il> wrote: > > > FALSE ECONOMICS ALERT! > > FALSE ECONOMICS ALERT! > > FALSE ECONOMICS ALERT! > > > > You say that "most modules DO work when moving to a newer version of > > Python". > > However when they do not work, it is a lot of work diagnosing the > > problem and finding which module needs to have both versions installed > > in parallel. > > > > It is better to spend the (relatively short and predictable) time > > maintaining a full virtualenv for each project. And if you are short > > on disk space, then today's disks are big and inexpensive - much less > > expensive than the time you spend trying to save few megabytes by not > > installing parallel versions. > > > > > > > > > > On Thu, 2021-07-22 at 20:02 +0300, Shlomo Solomon wrote: > > > On Thu, 22 Jul 2021 19:50:46 +0300 > > > Omer Zak <w...@zak.co.il> wrote: > > > > > > > Why do you want to avoid having to re-install modules for each > > > > version/environment? > > > > > > > The short answer: too much work > > > > > > The slightly longer answer: Although there are certainly changes > > > between versions of Python and/or modules, most modules DO work when > > > moving to a newer version of Python. I don't remember re-installing > > > everything when upgrading to a newer version of Python. > > > > > > But here, my problem is not upgrading, but keeping both versions. > > > > > > > > > > > > > > > > In the general case, a module version is compatible only with a > > > > subset > > > > of Python versions, due to API changes from Python version to > > > > Python > > > > version. > > > > > > > > You also want to let each project decide with which module version > > > > it > > > > wants to work, due to potential incompatibilities between module > > > > versions (it is no accident that pip freeze preserves installed > > > > module > > > > versions). > > > > > > > > > > > > On Thu, 2021-07-22 at 19:37 +0300, Shlomo Solomon wrote: > > > > > Omer Zak <w...@zak.co.il> wrote: > > > > > > The answer to your prayers is pyenv. > > > > > > It allows you to install multiple Python versions in parallel, > > > > > > and > > > > > > for > > > > > > each version you can maintain several virtualenvs. > > > > > > > > > > Dan Yasny <dya...@gmail.com> wrote: > > > > > > How about using virtualenv for alternative versions? > > > > > > > > > > Yes, I know about pyenv and virtualenv, but wouldn't I have to > > > > > re-install modules for each version/environment? That's what I'm > > > > > trying > > > > > to avoid. > > > > > > > > > > -- > Shlomo Solomon > http://the-solomons.net > Claws Mail 3.17.5 - KDE Plasma 5.18.5 - Kubuntu 20.04 > > _______________________________________________ > Linux-il mailing list > Linux-il@cs.huji.ac.il > http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il _______________________________________________ Linux-il mailing list Linux-il@cs.huji.ac.il http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il
