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Re: How modify numbers in a region by a multiplier?


From: Juanma Barranquero
Subject: Re: How modify numbers in a region by a multiplier?
Date: Mon, 5 Jul 2010 13:46:24 +0200

On Mon, Jul 5, 2010 at 11:49, Seweryn Kokot <address@hidden> wrote:

> Can we say that the second
> version is more elispy (more elegant and safer) than the first one?

That is hard to say; different tastes, etc.

I personally would write it like this:

(defun my-multiply-numbers-in-region-or-buffer (&optional multiplier
float-points)
  (interactive
   (list
    (read-number "Specify a multiplier: " 0.001)
    (read-number "Specify the number of significant figures: " 3)))
  (let ((region (use-region-p)))
    (save-restriction
      (widen)
      (narrow-to-region (if region (region-beginning) (point-min))
                        (if region (region-end) (point-max)))
      (goto-char (point-min))
      (while (re-search-forward "\\([0-9.]+\\)" nil t)
        (replace-match (format (concat "%." (number-to-string
float-points) "f" )
                               (* (string-to-number (match-string 1))
multiplier))))
      (message "Numbers in %s modified by multiplier %s."
               (if region "region" "buffer")
               multiplier))))

but that does *not* mean that it is more elegant or lispy; just more
to my tastes :-)

>        (save-restriction

you should use here
          (widen)

>          (narrow-to-region beg end)

    Juanma



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