Filter out entries for the same package in other repositories (melpa, marmelade, etc.)

Question

My package-archive variable is set to:

(("melpa-stable" . "http://stable.melpa.org/packages/")
 ("melpa" . "http://melpa.org/packages/")
 ("marmalade" . "http://marmalade-repo.org/packages/")
 ("gnu" . "http://elpa.gnu.org/packages/"))

which means that most packages appear twice or more in my package-list-packages output. Can this be avoided? Can this be avoided in a smart way?

Here's an example output :

  abl-mode           0.9.0         available  marmalade  Python TDD minor mode
  abl-mode           20170604.1309 available  melpa      Python TDD minor mode
  ac-R               0.2           available  marmalade  Autocompletion routines for R
  ac-cider           0.2.0         available  marmalade  Clojure auto-complete sources using CIDER
  ac-cider           0.2.3         available  melpa-s... Clojure auto-complete sources using CIDER
  ac-cider           20161006.19   available  melpa      Clojure auto-complete sources using CIDER
  ac-geiser          0.1           available  melpa-s... Auto-complete backend for geiser
  ac-geiser          0.1           available  marmalade  Auto-complete backend for geiser
  ac-geiser          20130928.2347 available  melpa      Auto-complete backend for geiser

I'd like to see this instead:

  abl-mode           0.9.0         available  marmalade  Python TDD minor mode
  ac-R               0.2           available  marmalade  Autocompletion routines for R
  ac-cider           0.2.3         available  melpa-s... Clojure auto-complete sources using CIDER
  ac-geiser          0.1           available  marmalade  Auto-complete backend for geiser

In this case I favoured marmalade and melpa-stable over melpa. Between marmalade and melpa-stable, I picked whichever had the higher version number.

A workaround would be to add an entry in package-pinned-packages for every package available, but that sounds very unsatisfying.

Answer 1

What you probably want is a combination of package-archive-priorities with package-menu-hide-low-priority set to t. Actually, just the second one will be sufficient for most cases.

EDIT:

To clarify: package-menu-hide-low-priority set to t will make package select only the highest-version variant in case package is available in multiple archives UNLESS package-archive-priorities implies different priorities.