Source

.emacs.d / vendor / yasnippet / snippets / emacs-lisp-mode / x-word-or-region.yasnippet

Full commit
# contributor: Xah Lee (XahLee.org)
# name: Command that works on region or word
# key: x-word-or-region
# --
;; example of a command that works on current word or text selection
(defun down-case-word-or-region ()
  "Lower case the current word or text selection."
(interactive)
(let (pos1 pos2 meat)
  (if (and transient-mark-mode mark-active)
      (setq pos1 (region-beginning)
            pos2 (region-end))
    (setq pos1 (car (bounds-of-thing-at-point 'symbol))
          pos2 (cdr (bounds-of-thing-at-point 'symbol))))

  ; now, pos1 and pos2 are the starting and ending positions
  ; of the current word, or current text selection if exists

  ;; put your code here.
  $0
  ;; Some example of things you might want to do
  (downcase-region pos1 pos2) ; example of a func that takes region as args
  (setq meat (buffer-substring-no-properties pos1 pos2)) ; grab the text.
  (delete-region pos1 pos2) ; get rid of it
  (insert "newText") ; insert your new text

  )
)