Re: Integrating package.el

[Stefan Monnier]

Tom> I think the default should be to activate the most recent package, and
Tom> to activate a package at install time.  So, if the user picks a specific
Tom> older version to activate (or equivalently deactivates the most recent
Tom> version), record that, and take it into account during activation.

> So it's a version override alist, where a missing entry implies the user
> wants the latest?  Do you mean something like this:

> ((package1 (repository1 path-to-specific-version1)) 
>  (package2 (repository2 path-to-specific-version2)))

> or am I misunderstanding something?

Don't know about you, but I seem to be missing something: why is the
word "repository" used here?  AFAIK the "repository" for package.el are
(typically remote) locations from where to download packages, and they
should have no interaction whatsoever with the part that worries about
installation and activation of packages (just like Debian's dpkg has no
idea about repositories).

BTW, my take on package activation and selection of versions (which IIRC
I already discussed with Tom a while back and we agreed to disagree) is
that activation of a package is controlled by lines in .emacs that take
a form similar to:

   (load "/some/where/package/init/file.el" 'package)

so there is no search or selection of package version at startup-time.
This means that when a new version of a package is installed, Emacs has
various ways to react to it:
- don't do anything, and at the next startup warn the user that the
  package he requested doesn't exist any more because it was replaced by
  a new version.
- update the "load" line right when the package gets upgraded (tho only
  for the .emacs of the user that performs the upgrade).
- use symlinks like "/some/where/elisp/sml-mode" pointing to
  "sml-mode-4.1" and use (load "/some/where/elisp/sml-mode/startup.el")
  so the symlink can be adjusted during the upgrade.
- use a different load, like

   (package-activate-latest "/some/where/elisp/sml-mode")

  which will look for the latest sml-mode package installed in
  /some/where/elisp/, or

   (package-activate-latest "sml-mode")

  which will look for the latest sml-mode package installed in
  any of the installation targets.


-- Stefan