Setting major-mode specific keybindings in emacs

Question

In my .emacs file, I want to add a key binding for a specific major mode (setting coffee-compile-file to C-c C-c in coffee-mode).

I've found a lot of instructions on using local-set-key and global-set-key, so I can easily add this binding once I've opened a file in coffee-mode, but it would be nice for this to be handled by .emacs.

Answer 1

Use the mode hook. C-h m shows information about the major mode, usually including what hook(s) it supports; then you do something like

(add-hook 'coffee-mode-hook ;; guessing
    '(lambda ()
       (local-set-key "\C-cc" 'coffee-compile-file)))

Answer 2

You can define the key in the mode specific map, something like:

(add-hook 'coffee-mode-hook
    (lambda ()
        (define-key coffee-mode-map (kbd "C-c c") 'coffee-compile-file)))

Or, more cleanly:

(eval-after-load "coffee-mode"
    '(define-key coffee-mode-map (kbd "C-c c") 'coffee-compile-file))

The second statement causes the key definition to only happen once, whereas the first causes the definition to happen every time coffee-mode is enabled (which is overkill).

Answer 3

Emacs 24.4 superseded eval-after-load with with-eval-after-load:

** New macro `with-eval-after-load'.
This is like the old `eval-after-load', but better behaved.

So the answer should be

(with-eval-after-load 'coffee-mode
  (define-key coffee-mode-map (kbd "C-c C-c") 'coffee-compile-file)
  (define-key erlang-mode-map (kbd "C-c C-m") 'coffee-make-coffee)
  ;; Add other coffee commands
)