Is it possible to have a complicated Emacs command as modeline?

Question

I have used the Emacs modeline for a while in my sources, to use tabs instead of spaces.

For example,

/* -*- indent-tabs-mode: t -*- */

For many uses (C++) this is not enough as Emacs insists in using tabulation for alignment. (See here: Modeline for indentation with tabs in Emacs)

Finally, I found a solution here: Emacs: Insert tab instead of spaces

(defun infer-indentation-style ()
  ;; if our source file uses tabs, we use tabs, if spaces spaces, and if        
  ;; neither, we use the current indent-tabs-mode                               
  (let ((space-count (how-many "^  " (point-min) (point-max)))
        (tab-count (how-many "^\t" (point-min) (point-max))))
    (if (> space-count tab-count) (setq indent-tabs-mode nil))
    (if (> tab-count space-count) (setq indent-tabs-mode t))))


(setq indent-tabs-mode nil)
(infer-indentation-style)

However, it is not a replacement for a modeling since it is a bunch of complicated code that I can't put in a single line between /* */.

Is it possible to convert this complicated into a single line modeling directive?

Answer 1

I would suggest to put the function definition into your emacs configuration file so it loads up when ever you start emacs.

(defun infer-indentation-style ()   ;; if our source file uses tabs, we use tabs, if spaces spaces, and if           ;; neither, we use the current indent-tabs-mode                                  (let ((space-count (how-many "^  " (point-min) (point-max)))
        (tab-count (how-many "^\t" (point-min) (point-max))))
    (if (> space-count tab-count) (setq indent-tabs-mode nil))
    (if (> tab-count space-count) (setq indent-tabs-mode t))))


(setq indent-tabs-mode nil)

Then you can use that function to evaluate buffer local variable with eval

/* -*- eval: (infer-indentation-style) -*- */