Re: Optional Arguments

[Arthur Miller]

pietru@caramail.com writes:

> I'm having a go at returning the two values from a function
>
> (defun word-markers ()
>   (let ((ma mb))
>     (skip-chars-backward "[:alpha:]")
>     (setq ma (point))
>     (skip-chars-forward "[:alpha:]")
>     (setq mb (point))
>     (cons ma mb) ))
>
> (defun test ()
>    (interactive)
>
>    (let ((deactivate-mark nil) bounds $ma $mb)
>       (if (use-region-p)
>          (setq $ma (region-beginning) $mb (region-end))
>          (save-excursion
>             (setq bounds (word-markers))
>             (setq $mu (car bounds))
>             (setq $mv (car bounds)) ))
>
>       (message "Bounds: %s" $bounds)
>       (message "Region: [%s, %s]" $ma $mb)  ))
>
> But something's not right.

You have probably made a typo when you are setq-ing 'mu' and 'mv'

> (setq $mu (car bounds)) <-- introducing new variable in global scope: $mu
> (setq $mv (car bounds)) <-- same here: $mv

> (message "Region: [%s, %s]" $ma $mb) <-- potentially nil vars $ma and $mb

You probably want somthing like this:

(defun test ()
   (interactive)
   (let ((deactivate-mark nil)
         bounds ma mb)
     (if (use-region-p)
         (setq ma (region-beginning) mb (region-end))
       (save-excursion
         (setq bounds (word-markers))
         (setq ma (car bounds))
         (setq mb (cdr bounds))))
   (message "Bounds: %s" (pp bounds))
   (message "Region: [%s %s]" ma mb)
   (message "Region string: [%s]" (buffer-substring ma mb))))