Re: elisp exercise: toggle-letter-case

[Xah <xahlee@gmail.com>]

On Oct 17, 6:06 pm, Nikolaj Schumacher <m...@nschum.de> wrote:
> Andreas Politz <poli...@fh-trier.de> wrote:
> > Giving the command a state makes it so much easier, because you
> > don't have to look at the text at all.
>
> I think looking at the text is actually less work.  It's only three
> lines of code.
>
> (defun toggle-region-case (&optional beg end)
>   (interactive (and transient-mark-mode mark-active
>                     (list (region-beginning)
>                           (region-end))))
>   (let ((pt (point))
>         case-fold-search
>         deactivate-mark)
>     (if beg
>         (goto-char beg)
>       (forward-word)
>       (setq end (point))
>       (backward-word))
>     (cond
>      ((looking-at "[[:upper:]][[:upper:]]") (downcase-region (point) end))
>      ((looking-at "[[:upper:]]") (upcase-region (point) end))
>      (t (upcase-initials-region (point) end)))
>     (goto-char pt)))
>
> regards,
> Nikolaj Schumacher

Nik, your solution failed the spec! lol.
It didn't work on single letter case, or words starting with number.

Andreas's solution works. But he did use a state. Minor fixable
problem is that it didn't consider the word/region's current state, so
that sometimes pressing the key doesn't do anything until one invokes
it again.

The use of “[[:upper]]” is great, and the use of properties to keep
state (very nice touch), and the use of “interactive” with optional
args.

Thanks guys.

  Xah
∑ http://xahlee.org/

☄