🚀 go-pugleaf

In article <1991May3.194541.12544@leland.Stanford.EDU>, alderson@Alderson.Stanford.EDU (Rich Alderson) writes:
|> >Is there some way to do this in Emacs, short of writing elisp code?
|> >(Or if not, has someone already written appropriate elisp code?)
|> 
|> Hmm.  Well, that would take a little elisp, using re-search-forward or
|> re-search-backward, and working like M-x replace-regexp or M-x
|> query-replace-regexp on the selected line.

I have written a function mapline that you might find useful.  It takes a
region, a function, and arguments, and applies the function to the args for
each line in the region.  (Note that a more robust implementation would use
unwind-protect or condition-case to trap errors in the function...)

(defun mapline (beg end f &rest args)
  "With the point set to the beginning of each line between BEGIN and
END, apply FUNCTION to ARGS and return a list of the result."
  (let* ((p (point-marker))
	(mlist (list 'mlist))
	(mtail (last mlist)))
    (save-restriction
      (narrow-to-region beg end)
      (goto-char (point-min))
      (beginning-of-line)
      (while (< (point) (point-max))
	(save-excursion
	  (setcdr mtail (list (apply f args)))
	  (setq mtail (cdr mtail)))
	(forward-line 1))
      )
    (goto-char p)
    (cdr mlist)))

I use this to call a certain function for each line that matches a regexp,
like this:

	(mapline
	 (point-min) (point-max)
	 (function (lambda ()
		     (if (re-search-forward zwgc-znol-output-regexp nil t)
			 (zwgc-znol-login)
		       (error "zwgc-znol-output-regexp failed!"))))))

Generalized iterators like this are extremely powerful.

-- 
Barr3y Jaspan, bjaspan@mit.edu
Watchmaker Computing