Emacs auto-save on switch buffer

Question

Call me lame, but I'm tired of my subconscious C-x C-s nervous twitch. I am switching buffers often enough and I think I would like to save a certain buffer as soon as I switch to another. I have not had the time yet to learn Emacs-Lisp basics.

Any hints on how to do this, or better solutions?

(On a related note, I found an autosave workaround that can save the current buffer as soon as you are idle for a given amount of time.)

Answer 1

To expand on Seth's answer, I'd do this:

(defadvice switch-to-buffer (before save-buffer-now activate)
  (when buffer-file-name (save-buffer)))
(defadvice other-window (before other-window-now activate)
  (when buffer-file-name (save-buffer)))
(defadvice other-frame (before other-frame-now activate)
  (when buffer-file-name (save-buffer)))

The check for buffer-file-name avoids saving buffers w/out files. You need to figure out all the entry points you use for switching buffers that you care about (I'd also advise other-window).

Answer 2

I'm kind of new to emacs lisp myself but this works in my testing:

(defadvice switch-to-buffer (before save-buffer-now)
  (save-buffer))

(ad-activate 'switch-to-buffer)

It's kind of annoying though because it's called after EVERY buffer (like scratch). So, consider this answer a hint.

When you want to disable it, you'll need to call:

(ad-disable-advice 'switch-to-buffer 'before 'save-buffer-now)
(ad-activate 'switch-to-buffer)