Set prefix key on load of minor mode

Question

I am trying to change the default prefix key C-c @ to C-c for outline-minor-mode:

      (define-key outline-minor-mode-map (kbd "C-c")
        (lookup-key outline-minor-mode-map (kbd "C-c @")))

This works fine if outline-minor-mode is already loaded. But I cannot find a way to put this into .emacs so that it is run whenever outline-minor-mode is activated.

I have tried:

(add-hook 'outline-minor-mode-hook
      (define-key outline-minor-mode-map (kbd "C-c")
        (lookup-key outline-minor-mode-map (kbd "C-c @"))))

Which gives:

Symbol's value as variable is void: outline-minor-mode-map

Answer 1

You must pass a function to add-hook. As it is you are evaluating the define-key call immediately, which is why you get the error.

with-eval-after-load is exactly what you are looking for.

(with-eval-after-load "outline"
  (define-key outline-minor-mode-map (kbd "C-c")
              (lookup-key outline-minor-mode-map (kbd "C-c @"))))