How to run whichever function is bound to a certain key

Question

There are a lot of occasions where, by default, the key-binding C-c C-c does something useful - e.g. in org-mode or magit. I would like to take whatever function C-c C-c runs, and bind that function to something like F8, without having to know what specific function is being called under the hood.

Thus: how can I take an existing key-binding, obtain the function which that key-binding would run, and then simply run that function?

(I'm aware it would take me 5 min to just make a list of functions that I'm interested in, and bind them appropriately in the respective modes - but I would nevertheless like to know how to achieve the above)

Answer 1

Trivially, with a keyboard macro:

(global-set-key (kbd "<f8>") (kbd "C-c C-c"))

n.b. That's not binding to a function; it's making <f8> issue the key sequence C-cC-c, which will in turn call whatever command it is bound to.

However as the C-cC-c sequence is reserved for major modes (refer to C-hig (elisp)Key Binding Conventions), you can trust that the local keymap will contain the binding of interest, and so you could use that to bind <f8> to the same command.

Here's an example I use to make RET do whatever M-j is bound to in any programming major mode.

(defun my-coding-config ()
  "Common behaviours for programming."
  (local-set-key (kbd "RET") (key-binding (kbd "M-j"))))

(add-hook 'prog-mode-hook 'my-coding-config)

Answer 2

To find which command C-c C-c runs, you can use key-binding, e.g.,

(key-binding (kbd "C-x C-f"))
;; => find-file

To run an interactive command from Lisp, you can use call-interactively, e.g.,

(call-interactively #'find-file)

(funcall won't work sometimes since it doesn't take care of the interactive spec.)

So maybe the following does what you want

(defun your-ctrl-c-ctrl-c ()
  (interactive)
  (let ((command (key-binding (kbd "C-c C-c"))))
    (when command
      (call-interactively command))))

(global-set-key (kbd "<f8>") #'your-ctrl-c-ctrl-c)