Hi,
I was fiddling around with the hydra package[1]. Hydra, which provides
easily defined popups. And I had the following idea:

Normally, I know my keybindings, so I type them in very fast. But
sometimes I just don't know what the next character of a prefix command
should be. So, when I wait long enough, a pre-defined hydra should be
spawned. And there is already something that does does something when a
partial keystroke sits there long enough: the echo-keystrokes timeout.

So, I searched for a hook to call my hydra there. But I didn't found one
(so please give me a hint, if i missed something). So I took a look into
keyboard.c and inserted a hook there that is called when the dash of an
partial keystroke is echoed. Together with the following lisp code I can
easily define general echo-keystroke timeouts:

(defvar echo-area-keystroke-keymap (make-sparse-keymap))

(define-key echo-area-keystroke-keymap (kbd "C-c p") 'hydra-projectile/body)

(defun echo-area-keystroke-echoed (&optional key)
  (let ((keystroke (or key (this-command-keys))))
    (when-let ((command (lookup-key echo-area-keystroke-keymap keystroke))
               (command-found (not (integer-or-marker-p command))))
      (ignore-errors
        (funcall command)
        (setq quit-flag t)))))

(add-hook 'echo-area-keystroke-hook 'echo-area-keystroke-echoed)

I don't know if this is useful, but I actually was really buffled that
at that point there is no hook. And I don't know if added the hook
correctly, since this is the very first time I touched a line of emacs C
source code. What do you think?

chris


[1] https://github.com/abo-abo/hydra