How to get the function by the keymap?

How to get the function by the keymap?

[Adam Jiang]

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Hi,

I am working on a minor mode in which I want to remap [backspace] key to
different functions in different situation. The lisp code looks like

(defun smart-operator-backspace ()
  (interactive)
  (cond ((looking-back "hello"))
     (save-excursion
        (replace-regexp-in-string ".*hello" "" (match-string 1))))
     (t
        (delete-char 1))))


However, (delete-char) never works for me. The reason is another minor mode
remapped the backspace key to function 'autopair-backspace'. Then, I
realized that I need a method to fetch the function by given keymap and get
it called rather thant have hardcoded deletion executed.

How can I do that with elisp code?

/Adam

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Re: How to get the function by the keymap?

[Eli Zaretskii]

> Date: Sun, 11 Nov 2012 01:09:02 +0900
> From: Adam Jiang <jiang.adam@gmail.com>
> 
> (defun smart-operator-backspace ()
>   (interactive)
>   (cond ((looking-back "hello"))
>      (save-excursion
>         (replace-regexp-in-string ".*hello" "" (match-string 1))))
>      (t
>         (delete-char 1))))
> 
> 
> However, (delete-char) never works for me. The reason is another minor mode
> remapped the backspace key to function 'autopair-backspace'. Then, I
> realized that I need a method to fetch the function by given keymap and get
> it called rather thant have hardcoded deletion executed.
> 
> How can I do that with elisp code?

I think you want lookup-key or local-key-binding.

Re: How to get the function by the keymap?

[Adam Jiang]

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2012/11/11 Le Wang <l26wang@gmail.com>

> On Sun, Nov 11, 2012 at 12:09 AM, Adam Jiang <jiang.adam@gmail.com> wrote:
> > However, (delete-char) never works for me. The reason is another minor
> mode
> > remapped the backspace key to function 'autopair-backspace'. Then, I
> > realized that I need a method to fetch the function by given keymap and
> get
> > it called rather thant have hardcoded deletion executed.
> >
> > How can I do that with elisp code?
>
> You don't want to dig through the keymaps yourself.  Just take your
> minor-mode out of the lookup chain and use `key-binding'.
>
> This is what I do here:
>
> https://github.com/lewang/rebox2/blob/master/rebox2.el#L2363
>

The code works like a charm. Thank you, Le.


>
> The deeper problem is that I have a chain of 3 functions from
> different minor-modes all bound to backspace.  They share the key
> happily, but Emacs lacks the mechanism to document this calling chain
> when I ask about <BACKSPACE> with C-h k.  I described the need to
> solve this as a feature request
> http://lists.gnu.org/archive/html/help-gnu-emacs/2012-10/msg00465.html
> , but there wasn't much interest.  :(
>

It seems this is a good idea. I'd like to help but I am pretty new to
elisp. I'll try to get some experience about the keybinding-chain thing
first.

Best regards,
/Adam

--
> Le
>

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