Highlight matched string in loops

Question

I'm writing a loop to perform some interactive replacements on matched strings:

(while (search-forward-regexp "REGEXP" nil t)
  (read-char "Options:...")
  ; Replacements...
  )

and I need the matched string to be "temporarily" highlighted until the replacement has done (or skipped).

What is the best way to get this behaviour?

(I figure out something like this:

(while (search-forward-regexp "REGEXP" nil t)

  (push-mark (match-beginning 0))
  (let ((x (make-overlay (mark) (point))))
    (overlay-put x 'face '(:background "grey20")))

  (read-char "Options:... ")
  (remove-overlays (mark) (point))
)

but I'm pretty sure it is not the best choice)

Answer 1

Don't set the mark. Just use (match-beginning 0). You can always let-bind a variable to that, if you're worried about the match-data changing.

(while (search-forward-regexp REGEXP nil t)
  (let* ((beg  (match-beginning 0))
         (xx   (make-overlay beg (point))))
    (overlay-put xx 'face 'YOUR-FACE)
    (read-char "Options:... ")
    (remove-overlays beg (point))))

---

C-h f push-mark tells you this, at the end:

Novice Emacs Lisp programmers often try to use the mark for the wrong purposes. See the documentation of set-mark for more information.

And C-h f set-mark tells you this, at the end:

Novice Emacs Lisp programmers often try to use the mark for the wrong purposes. The mark saves a location for the user's convenience. Most editing commands should not alter the mark. To remember a location for internal use in the Lisp program, store it in a Lisp variable. Example:

(let ((beg (point))) (forward-line 1) (delete-region beg (point))).