[Asking for ELisp Advice] Binding a local keybind when a minor-mode is
on.
reddit / emacs

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yep808 · 2022-02-16 02:24

I'm using evil-mode, lsp-mode, and lsp-ui-mode. I'd like to bind evil-
mode's "K" key (originally "evil-lookup") to be "lsp-ui-doc-glance"
whenever I am in a lsp-ui-mode enabled buffer. My idea is to run a
condition check whenever I'm entering a new buffer, with the buffer-
list-update-hook. My code snippet below seems to be working (having
tested thoroughly though), but I wonder if there is a more elegant way
to achieve this:

    (add-hook 'buffer-list-update-hook
              #'(lambda () (when (bound-and-true-p lsp-ui-mode)
                             (define-key evil-motion-state-local-map
(kbd "K") #'lsp-ui-doc-glance))))

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00-11 · 2022-02-16 03:47

Doesn't the minor mode have a keymap? If it does, just bind your key
in that map. (I'm probably not understanding what you're asking...)

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yep808 · 2022-02-16 03:58

I see your point. The problem is that I'm using everything under evil-
mode, and I want to bind literally the letter "K" to invoke lsp-ui-
doc-glance when I'm in evil's normal mode. If I simply do (define-key
lsp-ui-mode-map (kbd "K") #'lsp-ui-doc-glance), then I won't be able
to type out "K" in evil's insert mode.

In short, I am trying to bind this key in both lsp-ui-mode AND evil-
mode.

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[deleted] · 2022-02-16 04:58

[deleted]

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7890yuiop · 2022-02-16 05:00

Untested:

    (with-eval-after-load "evil"
      (define-key evil-motion-state-local-map (kbd "K")
        `(menu-item "" nil :filter ,(lambda (_)
                                      (if (bound-and-true-p lsp-ui-
mode)
                                          #'lsp-ui-doc-glance
                                        #'evil-lookup)))))

`evil-motion-state-local-map` sounds buffer-local, so that might not
be right.  I don't know anything much about `evil` or its keymaps
though.

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yep808 · 2022-02-16 06:22

Thanks! This snippet works fine, I should've wrapped my original
snippet with "with-eval-after-load" too. I'd love to read more about
"menu-item", could you point me somewhere? I tried searching but
didn't really find much. Except
[this](https://lists.gnu.org/archive/html/bug-gnu-
emacs/2020-12/msg01291.html) thread.

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7890yuiop · 2022-02-16 08:09

`C-h i g (elisp)Extended Menu Items`

Emacs menus are keymaps, and there's some functionality designed for
menus which happens to be very useful for regular key bindings as
well.  In the case of `:filter` the function returns either the
command to use, or `nil` to say "continue looking in other keymaps".
Here we're unconditionally returning a command, but which one varies
based on `lsp-ui-mode`.

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yyoncho · 2022-02-16 12:34

`(evil-define-key 'normal 'lsp-ui-doc-mode-map "K" 'lsp-ui-doc-
glance)`

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yep808 · 2022-02-16 15:48

Thanks for the reply, but this doesn't seem to work. It'll enable lsp-
ui-doc-glance even in non-lsp enabled buffers. Not sure if it's a
problem with evil. So far the only snippet I got working reliably is:

    (with-eval-after-load 'evil
      (add-hook 'buffer-list-update-hook
                #'(lambda ()
                    (when (bound-and-true-p lsp-ui-mode)
                      (define-key evil-motion-state-local-map (kbd
"K") #'lsp-ui-doc-glance)))))