If you, like me tend to carry around or "cloud around" a single .emacs file so you end up with similar environments wherever you have an Emacs install, you know it's a little painful to ensure that you have the same set of basic packages installed on each one of your Emacs installations. As I had mentioned before I don't use that many third party packages so my Emacs configurations aren't that complicated, but I always prefer to have the computer remember things so I don't have to.
As I started using ELPA last year, I decided to investigate if I could use ELPA and a little custom code to download and install the packages that I know I want everywhere. One evening I got bored enough to write a function that tests for the presence of a bunch of basic packages that I want to have on every Emacs install. It's not trying to be fancy and automate things to the n-th degree as I didn't want to spend the time each time I start Emacs, so I just have to remember to invoke the function after a new install. Here is the function, in all its simple glory:
(defun install-required-packages () (if (>= emacs-major-version 24) (progn (setq package-archives '(("ELPA" . "http://tromey.com/elpa/") ("gnu" . "http://elpa.gnu.org/packages/") ("marmalade" . "http://marmalade-repo.org/packages/") ("melpa" . "http://melpa.milkbox.net/packages/") )) (package-refresh-contents) (when (not (require 'bm nil t)) (package-install 'bm)) (when (not (require 'icicles nil t)) (package-install 'icicles)) (when (not (require 'smex nil t)) (package-install 'smex)) (when (not (require 'zenburn-theme nil t)) (package-install 'zenburn-theme)) )))