Re: How to define a prefixed map for a minor mode?

[Joost Kremers]

On Sun, Jun 07 2020, Marcin Borkowski wrote:
> Hi all,
>
> continuing my work on a (simplistic) Emacs CAT, I want to define 
> a minor
> mode.  However, I'm stuck on defining its keymap.  I want all 
> the
> commands prefixed by e.g. `C-c .', and here's what I have:
>
> --8<---------------cut 
> here---------------start------------->8---
> (setq ecat-basic-map (make-sparse-keymap))
>
> (define-key ecat-basic-map (kbd "p") 
> #'ecat-highlight-previous-sentence)
> (define-key ecat-basic-map (kbd "n") 
> #'ecat-highlight-next-sentence)
> (define-key ecat-basic-map (kbd ".") 
> #'ecat-highlight-this-sentence)
>
> (easy-mmode-defmap ecat-mode-map
>   `(((kbd "C-c .") . ecat-basic-map))
>   "Keymap for `ecat-mode'.")
>
> (define-minor-mode ecat-mode
>   "Toggle Emacs CAT mode."
>   :lighter " CAT"
>   :keymap ecat-mode-map
>   (if ecat-mode
>       (ecat-highlight-this-sentence)
>     (delete-overlay ecat-sentence-overlay)))
> --8<---------------cut 
> here---------------end--------------->8---
>
> Alas, this does not seem to work - after pressing `C-c .' (when 
> the mode
> is one!) I get "C-c . is undefined".
>
> What am I doing wrong?  Is there a "canonical" method of 
> defining
> a minor mode whose bindings start with some prefix?
>
> TIA,

In one package of mine, I do this:

```
(eval-and-compile
 (define-prefix-command 'ebib-slave-map)
 (suppress-keymap 'ebib-slave-map 'no-digits)
 (define-key ebib-slave-map "c" #'ebib-slave-create-slave)
 (define-key ebib-slave-map "a" #'ebib-slave-add-entry)
 (define-key ebib-slave-map "d" #'ebib-slave-delete-entry)
 (define-key ebib-slave-map "m" #'ebib-slave-switch-to-master))
```

and in the major mode's map:

```
(defvar ebib-index-mode-map
 (let ((map (make-keymap)))
   (suppress-keymap map 'no-digits)
   ;; [...]
   (define-key map "M" 'ebib-slave-map)
   ;; [...]
   map)
 "Keymap for the ebib index buffer.")
```

I'm not sure if that's what you're looking for, though, because 
`ebib-slave-map` isn't tied to a minor mode. But perhaps you can 
adapt it to your needs.

--
Joost Kremers
Life has its moments