Question

I want to show a normal buffer to the user but I want to save what s/he has written in XML format. can I do this in anyway in Emacs? Using some function or etc?

NOTE:

normal buffer: Text without markup … vs. …
XML format: a file that has XML tags and ll the content of the file/buffer are stored as records ..

Answer 1

It saves transform buffer in the file with extra suffix .xml

(defun transform-file-on-save ()
  (let ((bufer-as-string (buffer-string))
    (new-file-name (concat  (buffer-file-name) ".xml")))
    (with-temp-buffer
      (insert bufer-as-string)
      ;; some operations in the buffer
      (goto-char (point-min))
      (replace-string "(" "<b>")
      (goto-char (point-min))
      (replace-string ")" "</b>")
      ;; save file
      (message "Writing file: %s" new-file-name)
      (write-region (point-min) (point-max) new-file-name nil 'quietly))))

(add-hook 'after-save-hook 'transform-file-on-save)

;; better have it around to get rid of the hook
;;(remove-hook 'after-save-hook 'transform-file-on-save)