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Re: Why can't local-set-key (kbd "n") in diff-mode ?
From: |
Alex Kost |
Subject: |
Re: Why can't local-set-key (kbd "n") in diff-mode ? |
Date: |
Sat, 19 Nov 2016 12:20:18 +0300 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/25.0.95 (gnu/linux) |
boyang (2016-11-18 17:31 +0800) wrote:
> Hi
Hello!
> Greetings,
> I'm a Emacs newbie, when I do the following:
> ----------------------------------------------------------------------------------------
> (add-hook 'diff-mode-hook
> (lambda ()
> (local-set-key (kbd "n") 'next-error-no-select)
> (local-set-key (kbd "p") 'previous-error-no-select)))
> ----------------------------------------------------------------------------------------
I would do it like this:
(with-eval-after-load 'diff-mode
(define-key diff-mode-shared-map (kbd "n") 'next-error-no-select)
(define-key diff-mode-shared-map (kbd "p") 'previous-error-no-select))
Such overriding of keys in the original maps always "works". The only
thing you need is to find a map where the keys are bound.
> It doesn't work, when I press "n" in "*Diff*", it stills run "diff-hunk-next"
> when I "C-h k n", it still shows "diff-hunk-next". Same also for "p".
>
> But
> 1. If I do the same thing in other mode, say "occur-mode-hook", it works in
> that mode.
> 2. If I set other key other than "n" in "diff-mode-hook", say "x", it works.
>
> So is there somebody can tell me the reason behind this ?
Good question! I've spent several minutes trying to understand this :-)
So if you look at the code ("M-x find-function diff-mode"), there is
this part:
;; Neat trick from Dave Love to add more bindings in read-only mode:
(let ((ro-bind (cons 'buffer-read-only diff-mode-shared-map)))
(add-to-list 'minor-mode-overriding-map-alist ro-bind)
...)
This means that the keys from 'diff-mode-shared-map' will override the
keys that you bind with 'local-set-key' (it modifies 'diff-mode-map').
Thus "n" and "p" are taken from 'diff-mode-shared-map'. But if you bind
"x" key, it is taken from 'diff-mode-map' because 'diff-mode-shared-map'
does not have "x" key (look at "M-x find-variable
diff-mode-shared-map").
--
Alex