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Have written this function to change the style for global-whitespace-mode. I describe the problem as follows. Suppose one calls (space-glow "tab-trail") followed by (space-glow "allvis"). But trying to do (space-glow "tab-trail") again, the style does not take effect.

(defun space-glow (form)
  "Global visualisation of tabs and trailing spaces."
  (interactive
   (list
    (let* ( (cseq '("allvis" "tab-trail" "disable")) )
      (completing-read " Space_glow: " cseq nil t "tab-trail"))))

(require 'whitespace)


(pcase form
    ("tab-trail"
     (setq whitespace-style '(face tab-mark tabs trailing))
     (global-whitespace-mode 1))
    ("allvis"
     (setq whitespace-style '(face tabs spaces trailing lines
            space-before-tab newline indentation empty
            space-after-tab space-mark tab-mark newline-mark))
     (global-whitespace-mode 1))
    ("disable"
     (global-whitespace-mode 0))) )
Dilna
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1 Answers1

0

Toggle the mode to have a new style take effect.

Here I just unconditionally turned off the mode to start with. You can simplify the code for the "disable" case accordingly, if you like.

(defun space-glow (form)
  "Global visualisation of tabs and trailing spaces."
  (interactive
   (list
    (let* ( (cseq '("allvis" "tab-trail" "disable")) )
      (completing-read " Space_glow: " cseq nil t "tab-trail"))))
  (require 'whitespace)
  (global-whitespace-mode 0) ; <========= Turn it off first.
  (pcase form
    ("tab-trail"
     (setq whitespace-style '(face tab-mark tabs trailing))
     (global-whitespace-mode 1))
    ("allvis"
     (setq whitespace-style
       '(face tabs spaces trailing lines
          space-before-tab newline indentation empty
          space-after-tab space-mark tab-mark newline-mark))
     (global-whitespace-mode 1))
    ("disable"
     (global-whitespace-mode 0))) )
Drew
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  • Is it safe to call (global-whitespace-mode 0) when a mode might not be available? whitespace-mode is a mode that is automatically available in emacs, correct? – Dilna Jul 20 '22 at 01:36
  • I don't understand your comment question. I put that after your require. – Drew Jul 20 '22 at 02:32
  • I understand the fix now. Because require imports (loads) the appropriate functionalities, then the value for whitespace-style can be set and used by the feature that uses it. Is it customary to require disabling a mode to reset a customisation variable? Are there packages that react dynamically to changes, and would it be the preferred behaviour? – Dilna Jul 20 '22 at 02:57
  • If depends on what setting the option does and what enabling the mode does. In this case, just changing the variable value without toggling the mode didn't do what you wanted. – Drew Jul 20 '22 at 19:27