Re: empty-line-p

[Andreas Roehler <andreas.roehler@easy-emacs.de>]

Stefan Monnier schrieb:
>>  (if (looking-at "^[ \t\f\r]*$")
>>      t
>>    nil)))
>>     
>
>   (if <foo> t nil)
>
> is an eta-regexp, which can be advantageously reduced to just <foo>.
>
>
>         Stefan
>
>
> PS: The classical eta-regexp is (lambda (x) (<foo> x)), which is equivalent to
> just <foo>.  Another variant is (cons (car <foo>) (cdr <foo>)), which
> eta-reduces to just <foo>.
>   

Thanks a lot both.

Rewrote it in order to let the user decide, which chars
should be considered as "empty".

Also provided an interactive spec.

__
Andreas Roehler


(defcustom empty-line-p-chars "^[ \t\f\r]*$"
  "Permitted chars on a line,
which should be considered as \"empty\" nonetheless"
 :type 'regexp
 :group 'convenience)

(defun empty-line-p (&optional ispec)
  "Returns t if cursor is at an empty line, nil otherwise.
Displays result in minibuffer when called interactive."
  (interactive "p")
  (save-excursion
    (beginning-of-line)
    (when ispec
      (message "%s" (looking-at empty-line-p-chars)))
    (looking-at empty-line-p-chars)))