Hiding and replacing modeline strings with clean-mode-line

If you are like me, you are probably using one or more minor modes, and most of them add their own lighter to the modeline to tell you that they are running. Common examples include “Abbrev” for Abbrev mode; “yas” for Yasnippet mode and so on. Unfortunately, modeline real estate is expensive, and if you are stuck on a small screen – or if you split your Emacs windows a lot – you will find that it is often truncated, possibly hiding useful information that you actually care about, such as Which Function Mode.

There is no feature in Emacs to selectively hide or compress modeline flotsam, so I have hacked together some code to do the job for you.

NOTE: If you use use-package you can use :diminish along with the diminish.el package to accomplish this

For instance, in my Emacs I can collapse the following modeline string:

(Python Hi AC yas Eldoc Abbrev)

Into:

(Py α υ)

I’ve chosen to completely obscure hi-lock-mode, abbrev-mode, and eldoc-mode but “compress” auto-complete-mode, yas/minor-mode, and python-mode.

I used Greek characters (How? C-u C-\ greek RET then C-\ to write Greek characters; see Diacritics in Emacs) but you can use Emoji or any other code point you want.

Here’s the code. Stick it in your emacs file, evaluate it, and you’re done. You can also force a refresh by running M-x clean-mode-line. Flymake will have to be turned off and back on for the changes to take effect in a buffer!

(defvar mode-line-cleaner-alist
  `((auto-complete-mode . " α")
    (yas/minor-mode . " υ")
    (paredit-mode . " π"))
  "Alist for `clean-mode-line'.

When you add a new element to the alist, keep in mind that you
must pass the correct minor/major mode symbol and a string you
want to use in the modeline *in lieu of* the original.")


(defun clean-mode-line ()
  (interactive)
  (loop for cleaner in mode-line-cleaner-alist
        do (let* ((mode (car cleaner))
                 (mode-str (cdr cleaner))
                 (old-mode-str (cdr (assq mode minor-mode-alist))))
             (when old-mode-str
                 (setcar old-mode-str mode-str))
               ;; major mode
             (when (eq mode major-mode)
               (setq mode-name mode-str)))))


(add-hook 'after-change-major-mode-hook 'clean-mode-line)