From mboxrd@z Thu Jan  1 00:00:00 1970
From: ludo@gnu.org (Ludovic =?utf-8?Q?Court=C3=A8s?=)
Subject: Re: Multiple versions
Date: Tue, 29 Dec 2015 16:21:48 +0100
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References: <n5n6as$slp$1@ger.gmane.org> <20151227052600.GA32379@thebird.nl>
	<20151227092027.GA1958@sagulo>
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In-Reply-To: <20151227092027.GA1958@sagulo> (Dmitry Bogatov's message of "Sun,
	27 Dec 2015 12:20:27 +0300")
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To: Dmitry Bogatov <KAction@gnu.org>
Cc: guix-devel@gnu.org

Dmitry Bogatov <KAction@gnu.org> skribis:

> Currently, I am at master branch. I want install parallel-20151122.
> But it is gone since 0877e. I propose to keep *all* versions,
> but just 'parallel' refer to latest.

First, I think it=E2=80=99s important to distinguish the source (the package
recipes in gnu/packages/*.scm) and the installed packages (stuff in
/gnu/store.)

Users can keep the versions they want in their store and in their
profiles.

For recipes, as Andreas noted, it would be terrible for Guix as a
project to provide and maintain zillions of different versions of each
package (keeping them all would be easy, but we want to provide packages
that actually build :-)).

However, users can write their own modules containing different versions
or variants of the packages.  For instance, you could write:

  (define-module (my-packages)
    #:use-module (gnu packages parallel))

  (define my-parallel
    ;; Inherit from the Parallel recipe that Guix provides, but override
    ;; the version being used.
    (package
      (inherit parallel)
      (version "x.y.z")
      (source (origin
                (method url-fetch)
                (uri (string-append "mirror://gnu/parallel/parallel-"
                                    version ".tar.bz2"))
                (sha256
                 (base32
                  "0phn9dlkqlq3cq468ypxbbn78bsjcin743pyvf8ip4qg6jz662jm")))=
)))

Then drop that in =E2=80=98GUIX_PACKAGE_PATH=E2=80=99, and run:

  guix package -i parallel-x.y.z

HTH,
Ludo=E2=80=99.