Re: Elisp beginner's question

[Tassilo Horn]

Uwe Siart <usenet@siart.de> writes:

Hi Uwe,

> ;; --------------------------------------------
> (defun toggle-show-trailing-whitespace ()
>   "Toggle highlighting of trailing whitespace."
>   (interactive)
>   (if show-trailing-whitespace
>     (setq show-trailing-whitespace nil)
>     (setq show-trailing-whitespace t)))
> ;; --------------------------------------------
>
> And - well - it works somehow, I don't see any misbehaviour so far.
> But I'd appreciate some experts' advice whether this approach is ok or
> whether it should be done differently.

Your function is ok, but this one is shorter. ;-)

--8<---------------cut here---------------start------------->8---
(defun toggle-show-trailing-whitespace ()
  "Toggle highlighting of trailing whitespace."
  (interactive)
  (setq show-trailing-whitespace (not show-trailing-whitespace)))
--8<---------------cut here---------------end--------------->8---

But I'd say most of the time you want to set this variable on a per-mode
basis and not on a per-buffer basis, right?  In that case you'd set the
variable in the mode's hook like this:

--8<---------------cut here---------------start------------->8---
(add-hook 'emacs-lisp-mode-hook
          (lambda ()
            (setq show-trailing-whitespace)))
--8<---------------cut here---------------end--------------->8---

Hope that helps,
Tassilo
-- 
Chuck Norris can skeletize a cow in two minutes.