From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ricardo Wurmus <rekado@elephly.net>
Subject: Re: installing python 2 and python 3 in the same profile
Date: Wed, 14 Mar 2018 09:40:27 +0100
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To: Ludovic =?utf-8?Q?Court=C3=A8s?= <ludo@gnu.org>
Cc: Guix-devel <guix-devel@gnu.org>, Ricardo Wurmus <ricardo.wurmus@mdc-berlin.de>


Ludovic Court=C3=A8s <ludo@gnu.org> writes:

>> How about a package property that defines a =E2=80=9Cconflicts?=E2=80=9D=
 predicate that
>> takes two packages of the same name and determines (e.g. by checking the
>> major version) if these two packages are conflicting?  If no such
>> predicate is provided we assume that packages with the same name cause a
>> conflict and prevent installation.
>
> Unfortunately it wouldn=E2=80=99t work in the general case where some pro=
file
> entries may be coming from ~/.guix-profile/manifest, as is the case when
> you do:
>
>   guix package -i python@2
>   guix package -i python@3
>
> I would suggest short-term solutions, which are not exclusive:
>
>   1. Add a =E2=80=98--allow-collisions=E2=80=99 flag to =E2=80=98guix pro=
file=E2=80=99 (we discussed it
>      before but didn=E2=80=99t get around to doing it apparently!).
>
>   2. Use different package names when we know things can be
>      parallel-installed: =E2=80=9Cpython2=E2=80=9D vs. =E2=80=9Cpython=E2=
=80=9D (I=E2=80=99m talking about the
>      package name, not its version string.)  That=E2=80=99s what distros =
usually
>      do, and I think it=E2=80=99s good enough.

Both of these are desirable solutions, I think.  =E2=80=9C--allow-collision=
s=E2=80=9D
would be an escape hatch, and renaming packages is much easier than the
=E2=80=9Cserialisable predicate=E2=80=9D idea.

--=20
Ricardo

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