elisp save selection to file

save-selection.el

;; Given a target buffer, copy the range from point to
;; mark in the current buffer to that other buffer.
(defun save-selection-to-file (target-buffer)
  (interactive "B")
  (copy-region-as-kill (point) (mark))
  (with-current-buffer target-buffer
    (save-excursion
      (erase-buffer)
      (yank)
      )
    )
  )