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bug#11410: 24.1.50; package.el `emacs' package information is broken
From: |
Toby Cubitt |
Subject: |
bug#11410: 24.1.50; package.el `emacs' package information is broken |
Date: |
Sat, 5 May 2012 14:52:45 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Sat, May 05, 2012 at 08:37:14AM -0400, Stefan Monnier wrote:
> > The Elisp manual "Conventional Headers for Emacs Libraries" node says:
> > The package code automatically defines a package named `emacs'
> > with the version number of the currently running Emacs. This can
> > be used to require a minimal version of Emacs for a package.
>
> BTW I highly doubt the usefulness of such a dependency. Package.el can
> use dependencies to automatically download&update needed packages, but
> it currently can't do that for `emacs', and in general it's can't do
> that at all (the same set of installed packages might even be used by
> different versions of Emacs).
>
> So such a dependency makes more sense as a load-time test (written in
> Elisp directly in the package's code) rather than as
> a package.el dependency.
Surely the idea is for packages to refuse to even *install* under Emacs
versions where they won't work (package.el displays an "emacs x.x not
available" in this case.)
As I understand it, with a load-time test package.el will still downland
and install the package successfully, even though the package won't
work. With the `emacs' version dependency, install will instead fail with
an informative message.
That seems like a useful feature to me.
(Even more useful when the package in question is actually being
installed as part of a chain of dependencies.)
Toby
--
Dr T. S. Cubitt
Mathematics and Quantum Information group
Department of Mathematics
Complutense University
Madrid, Spain
email: tsc25@cantab.net
web: www.dr-qubit.org