Change post-self-insert-hook only in one mode

Question

I have written a functionality that inserts the word end at end of blocks in a lua major mode. How i do it is to check if a space character has been typed, if yes is the word before the space for example function, if yes print the end. Now adding my funcionality to post-self-insert-hook will change its hooks-list in all modes and buffers. How can i specify it to happen only in lua-mode?

Here is my code in my init.el:

(add-hook 'lua-mode-hook 'mein-lua-mode-hook)
(defun put-end ()
  "print end of blocks"
  (interactive)
  (backward-char)
  (when (member (thing-at-point 'word) '("function"))
    (progn
      (save-excursion (insert "  " "end"))
      (forward-char))))
(defun spacep ()
  (if (and (derived-mode-p 'lua-mode)(member (char-before) '(13 32)))
      (put-end)))
(defun mein-lua-mode-hook ()
  "Tastaturanbindungen fuer das Lua-Mode"
  ;;; some other things come here
  (add-hook 'post-self-insert-hook 'spacep))

Answer 1

That's what the local argument to add-hook is for. I.e. use

(add-hook 'post-self-insert-hook #'spacep nil 'local)

Answer 2

To have it affect only one mode, have the function test the current mode and do nothing if it is not (derived-mode-p THE-MODE). In your case, e.g.:

(defun spacep ()
  (when (and (derived-mode-p 'lua-mode)
             (member (char-before) '(13 32)))
    (put-end)))