Re: view-mode keymap

[Daimrod <daimrod@gmail.com>]

Jambunathan K <kjambunathan@gmail.com> writes:

> Daimrod <daimrod@gmail.com> writes:
>
>> Jambunathan K <kjambunathan@gmail.com> writes:
>>
>>> I think, `make-composed-keymap' can help here.
>>>
>>>
>>>> I like `view-mode' but it conflicts with others minor mode map (paredit
>>>> in my case).
>>>>
>>>> I would like to know if there is a better way to make a keymap that
>>>> takes precedence over the others than manipulating
>>>> `minor-mode-map-alist'.
>>>>
>>>> Here is my current implementation:
>>>>
>>>> (add-hook 'view-mode-hook
>>>>           (lambda ()
>>>>             ;; Makes sure `view-mode-map' is the first minor mode map
>>>>             ;; available in `minor-mode-map-alist', because in case of
>>>>             ;; conflicting bindings, the first one is used.
>>>>             (unless (eq 'view-mode (caar minor-mode-map-alist))
>>>>               (setf minor-mode-map-alist
>>>>                     (cons (cons 'view-mode view-mode-map)
>>>>                           (cl-remove 'view-mode minor-mode-map-alist
>>>>                                      :key #'car))))))
>>
>> I've looked at it but I don't see how it can help. I don't want to
>> create a new keymap, I want `view-mode-map' to take priority over other
>> keymaps.
>
> I was hoping that something like this
>
>     (use-local-map
>      (make-composed-keymap view-mode-map
>                            (current-local-map)))    
>         
> will put `view-mode-map' on top of the keymap stack and thus overwrite
> paredit's bindings.
>
> I see that DEL (backspace) key is shared between view-mode and paredit.
> My little experimentation that the above snippet failst to produce the
> effect expected by me.
>
> Do you think I am reading the doc of the APIs (used above) incorrectly?

No, the problem is not the way you're building the keymap, but how
keymaps are searched.

From (info "(elisp) Searching Keymaps")
> (or (cond
>      (overriding-terminal-local-map
>       (FIND-IN overriding-terminal-local-map))
>      (overriding-local-map
>       (FIND-IN overriding-local-map))
>      ((or (FIND-IN (get-char-property (point) 'keymap))
>           (FIND-IN TEMP-MAP)
>           (FIND-IN-ANY emulation-mode-map-alists)
>           (FIND-IN-ANY minor-mode-overriding-map-alist)
>           (FIND-IN-ANY minor-mode-map-alist)
>           (if (get-text-property (point) 'local-map)
>               (FIND-IN (get-char-property (point) 'local-map))
>             (FIND-IN (current-local-map))))))
>     (FIND-IN (current-global-map)))

It searches through `minor-mode-map-alist' _before_ looking at
`current-local-map'.

I could use `overriding-local-map' instead of `current-local-map' if it
was a buffer local variable. But it's not, and I'm afraid that making it
buffer local might break things in a weird way.

>>
>> I've looked at the documentation and it seems that changing the order in
>> `minor-mode-map-alist' is the only way to manage priorities between
>> keymap, because they shouldn't conflict in there first place.

-- 
Daimrod/Greg