echo-area-keystroke-hook

echo-area-keystroke-hook

[Christian Dietrich]

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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


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From f3e1bd52c57e536cd8b61568e1d0cc8de9c1d6ba Mon Sep 17 00:00:00 2001
From: Christian Dietrich <christian.dietrich@informatik.uni-erlangen.de>
Date: Mon, 14 Dec 2015 23:18:08 +0100
Subject: [PATCH] New 'echo-area-keystroke-hook'

The echo-area-keystroke-hook is called when a keystroke is inserted partially
and the keystroke is printed to the echo area.

* src/keyboard.c: New hook is called when dash is printed to the echo area.
---
 src/keyboard.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/src/keyboard.c b/src/keyboard.c
index 02bc7d2..1a2b621 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -530,6 +530,11 @@ echo_dash (void)
   kset_echo_string (current_kboard,
 		    concat2 (KVAR (current_kboard, echo_string), dash));
   echo_now ();
+
+  /* Call the hook indicating that a keystroke was printed to the echo
+     area */
+  safe_run_hooks (Qecho_area_keystroke_hook);
+
 }
 
 static void
@@ -11008,6 +11013,7 @@ syms_of_keyboard (void)
   DEFSYM (Qhelp_form_show, "help-form-show");
 
   DEFSYM (Qecho_keystrokes, "echo-keystrokes");
+  DEFSYM (Qecho_area_keystroke_hook, "echo-area-keystroke-hook");
 
   Fset (Qinput_method_exit_on_first_char, Qnil);
   Fset (Qinput_method_use_echo_area, Qnil);
@@ -11396,6 +11402,14 @@ See also `pre-command-hook'.  */);
   DEFSYM (Qecho_area_clear_hook, "echo-area-clear-hook");
   Fset (Qecho_area_clear_hook, Qnil);
 
+  DEFVAR_LISP ("echo-area-keystroke-hook", Vecho_area_keystroke_hook,
+               doc: /* Normal hook run after a partial key input is
+printed to the echo area. If an unhandled error happens in this hook,
+the function in which the error occured is unconditionally removed,
+since otherwise the error might happen repeatedly and make Emacs
+nonfunctional. */);
+  Vecho_area_keystroke_hook = Qnil;
+
   DEFVAR_LISP ("lucid-menu-bar-dirty-flag", Vlucid_menu_bar_dirty_flag,
 	       doc: /* Non-nil means menu bar, specified Lucid style, needs to be recomputed.  */);
   Vlucid_menu_bar_dirty_flag = Qnil;
-- 
2.6.2

Re: echo-area-keystroke-hook

[John Wiegley]

>>>>> Christian Dietrich <stettberger@dokucode.de> writes:

> 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

Also see:

    https://github.com/justbur/emacs-which-key
    https://github.com/kai2nenobu/guide-key
      (http://pragmaticemacs.com/emacs/get-pop-up-help-for-keybindings-with-which-key/)

-- 
John Wiegley                  GPG fingerprint = 4710 CF98 AF9B 327B B80F
http://newartisans.com                          60E1 46C4 BD1A 7AC1 4BA2

Re: echo-area-keystroke-hook

[Christian Dietrich]

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On Mon, 2015-12-14 at 14:38 -0800, John Wiegley wrote:
> > > > > > Christian Dietrich <stettberger@dokucode.de> writes:
> 
> > 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
> 
> Also see:
> 
>     https://github.com/justbur/emacs-which-key
>     https://github.com/kai2nenobu/guide-key
>       (http://pragmaticemacs.com/emacs/get-pop-up-help-for-keybinding
> s-with-which-key/)

Oh, that's great, I wasn't aware of these. Thank you very much :-)

chris
-- 
No documentation is better than bad documentation

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Re: echo-area-keystroke-hook

[Artur Malabarba]

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> > > > > > > Christian Dietrich <stettberger@dokucode.de> writes:
> >
> > > 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

Hydra has an option to delay the popup. That way you only see the hydra if
you pause after the first key.
that should do what you want and would be simpler than setting up a hook.

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RE: echo-area-keystroke-hook

[Drew Adams]

> Also see:
> 
>     https://github.com/justbur/emacs-which-key
>     https://github.com/kai2nenobu/guide-key
>       (http://pragmaticemacs.com/emacs/get-pop-up-help-for-keybindings-with-
> which-key/)

And Icicles key completion.  It is on-demand (`S-TAB'),
but you could make it automatic, on a delay if you want.

http://www.emacswiki.org/emacs/Icicles_-_Key_Completion