Getting Emacs to untabify when saving certain file types (and only those file types)

Question

I have the following in my .emacs file:

 (defun c++-mode-untabify ()
   (save-excursion
     (goto-char (point-min))
     (while (re-search-forward \"[ \\t]+         


        

Answer 1

The documentation in my Emacs says that make-local-hook is now obsolete as of 21.1, since add-hook now takes an optional argument for making a hook buffer-local. So you could try:

(add-hook 'c++-mode-hook
           '(lambda ()
              (add-hook 'write-contents-hooks 'c++-mode-untabify nil t)))

Another option is to have the c++-mode-untabify function check the current mode. I'd probably just write that as something like:

(defun c++-mode-untabify ()
  (if (string= (substring mode-name 0 3) "C++")
      (save-excursion
       (delete-trailing-whitespace)
       (untabify (point-min) (point-max)))))