Change the order of Minor Modes on the Modeline

Question

I've recently been using the delight package to override mode line strings and control whether or not they're displayed, and it's great, but I'd like also to control the order in which minor mode strings appear on the modeline. For example making sure the projectile mode line string always appears as the second string.

The order in which the mode line strings appears to correspond to their locations in minor-mode-alist (?). Is there a way to control the ordering which doesn't require sorting the values of this list?

Answer 1

Order of minor mode lighters (before)

Order of minor mode lighters (after)

(add-hook
 'after-load-functions
 (prog1
     (defun re-arrange-minor-mode-alist (&rest _)
       (cl-loop with modes =
                '(
                  ;; order in which you want the minor mode lighters to
                  ;; appear
                  projectile-mode
                  hs-minor-mode
                  outline-minor-mode
                  ;; To get the current order of entries, and what to plug in
                  ;; here do `M-x pp-eval-expression RET (mapcar #'car minor-mode-alist)'
                  )
                for mode in (nreverse modes)
                for mode-line-entry = (assq mode minor-mode-alist)
                when mode-line-entry do
                (assq-delete-all mode minor-mode-alist)
                (add-to-list 'minor-mode-alist mode-line-entry)))
   (re-arrange-minor-mode-alist)))

Answer 2

The order in which the mode line strings appears to correspond to their locations in minor-mode-alist (?).

Yes, and in a very direct sense -- minor-mode-alist is literally the mode line component responsible for rendering those values.

Is there a way to control the ordering which doesn't require sorting the values of this list?

On account of the above, no -- not unless you generate some alternative way of rendering that part of the mode line.

You could use after-load-functions to re-order minor-mode-alist every time any library is loaded (which should do the trick).

Alternatively...

For example making sure the projectile mode line string always appears as the second string.

...use delight.el to hide projectile entirely, but firstly copy that value into a separate mode line construct which you put directly in front of minor-mode-alist (i.e. between the major mode and the minor modes).

That's not entirely trivial, as all of those things are encapsulated in the value of mode-line-modes, but see https://emacs.stackexchange.com/a/3927/454 for an example of manipulating that.

I would recommend the re-ordering approach as the simpler option, though.