Re: Emacs Package Management

[Bob Rogers <rogers-emacs@rgrjr.dyndns.org>]

   From: Rupert Swarbrick <rswarbrick@gmail.com>
   Date: Thu, 17 Sep 2009 12:50:04 +0100

   . . .

   One thing to bear in mind is that shared libraries on unix are probably
   a simpler problem than emacs libraries: I can install multiple versions
   of libfoo and the dynamic linker will select the correct one for an
   application. Trying to install multiple versions of an emacs package
   would result in a godawful mess, because it's not just a list of
   functions that can be called.

   I don't know how one could solve that, so I suspect that the only
   solution is to only allow one version of a package at once . . .

   Rupert

This does not seem so hard.  If the "installed" location depended on the
Emacs version, e.g. by having the version number as part of the
directory name, then you could easily have one version of a package per
Emacs version.  The downside is that if you want to have all X versions
of Emacs on a given system find the "same" package, you would have to
install that package X times.  But this seems like a small price to pay
to be certain that each installed package version is known to work with
that version of Emacs -- and that it has been byte-compiled by the right
version of the byte compiler.

   FWIW, I don't usually have more than one version of Emacs per system.
So, for packages installed by the sysadmin, I think version-dependence
would rarely be an issue.  But if I'm not the sysadmin, and have to
install packages in my shared home directory, version-dependence could
be quite important if I need to use a variety of Emacsen on different
systems.

					-- Bob Rogers
					   http://www.rgrjr.com/