Replace word at point preserving the case pattern

Question

Currently, I am doing the replacement of the word under the cursor on a script using:

(setq bounds (bounds-of-thing-at-point 'word))
(setq pos1 (car bounds))
(setq pos2 (cdr bounds))
(delete-region pos1 pos2)
(insert newword)

But this does not preserve the case pattern of the original word. The function replace-match would preserve case, but it would require me to do a search before; something like this:

(left-word)
(search-forward originalword)
(replace-match newword)

Is there a replace command which would allow me to replace the word at point preserving the original word pattern case? If not, am I missing a simple way to write one?

Answer 1

The replace-match function is your best bet. It's a C primitive and that's where the case preservation logic is implemented.

replace-match replaces the text indicated by the match data. You can call set-match-data to set the match data to bounds that don't result from a search.

(save-match-data
  (let ((bounds (bounds-of-thing-at-point 'word)))
    (set-match-data (list (car bounds) (cdr bounds)))
    (replace-match new-word)))