Emacs lisp “shell-command-on-region”

Question

In GNU Emacs, I want to run a program, figlet, on the currently selected text. I then want to comment the region which is produced.

I have figured out how to do it using

Answer 1

It is not a very good idea to use an interactive command like shell-command-on-region in a lisp program. You should use call-process-region instead:

(defun figlet-region (&optional b e) 
  (interactive "r")
  (call-process-region b e "figlet" t t)
  (comment-region (mark) (point)))

It should be more resilient against various user options.