Re: Delegating user-reserved key binding space definition to users

[Stefan Monnier <monnier@iro.umontreal.ca>]

>    - Multiple modifiers such as M-S-* or long sequences such as C-* C-* *.
>    M-? is also an example of what I consider to require multiple-modifiers on
>    a US key layout where '?' requires shift.
>    - High-value space such as M-* and C-*
[...]
> It was suggested that advice might work for implementation, up to a point,
> since define-key doesn't have a dedicated code of some type I'm unaware of.

Doing it inside `define-key` is problematic because you can bind a key
to `C-a C-b C-c` via three calls to `define-key`, so you won't be able
to detect the problem reliably in all cases:

    (let* ((map1 (make-sparse-keymap))
           (map2 (make-sparse-keymap))
           (map3 (make-sparse-keymap)))
      (define-key map1 [?\C-a] map2)
      (define-key map2 [?\C-b] map3)
      (define-key map3 [?\C-c] 'foo))


-- Stefan