Re: PYTHONPATH issue analysis - part 3

[Pjotr Prins]

On Tue, Mar 13, 2018 at 10:23:08PM +0100, Ludovic Courtès wrote:
> > Preliminary Proposal
> > =======================
> >
> > To be able to install different minor versions of Python in the same
> > profile, any environment variable should contain the minor version, too.
> > E.g. …-3.5.
> 
> If you’re suggesting to have a ‘PYTHONPATH3-5’ environment variable
> instead of ‘PYTHONPATH’, I agree it could be helpful if we are to
> install different versions of Python in one profile.  

Another problem is that it does not cover special cases where, for
example you compile Python with SSL and without. You don't want them
to share user installed libs. That is why I stick in the Hash value.

Ruby example

  https://gitlab.com/pjotrp/guix-notes/blob/master/scripts/ruby-guix-env

admittedly I no longer use that much. But I would if I just quickly
wanted to try a gem/module and make sure it is isolated.

> However, it’s a choice for upstream to make, and upstream did not
> make that choice.

Sometimes upstream can do with good ideas ;). The shared use of
PYTHONPATH between versions of Python2 and 3 is as brain dead as it
can be. I see people trip over it regularly, including myself. Great
time waster, if nothing else.

> There’s one case where we went our way instead of following upstream,
> and that is ‘GUIX_LOCPATH’.  There are strong justifications, though.

Would not work with multiple versions in one profile though. Anyway,
Hartmut covered all that.

Pj.
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