Rebind key to a different character in a specific mode?

Question

I already tried some different ways of doing this, but never got it quite right, so I put it here.

When working in buffers using some specific modes (lisp-mode, emacs-lisp-mode) I want to make it so a specific key inserts a different character.

In my case,

If Elisp / Lisp mode activated:

• pressing key ö inserts character (
• pressing key ä inserts character )

How can I do this?

Answer 1

This should work:

(define-key
  emacs-lisp-mode-map
  "ö"
  (lambda () (interactive) (insert "(")))
(define-key
  emacs-lisp-mode-map
  "ä"
  (lambda () (interactive) (insert ")")))

Most major modes have an associated *-map variable, which holds the keyboard bindings for that mode. You can use define-key to add bindings to those maps.