Question on remapping keys

Question on remapping keys

[Drew Adams]

I have a minor mode that redefines some of the minibuffer keymaps (e.g.
minibuffer-local-completion-map). I want turning on the mode to implement
the new minibuffer bindings, and turning it off to restore the minibuffer
bindings of vanilla Emacs.

In some cases, I reuse key sequences that are bound in the global map,
binding them to other commands in minibuffer maps. Those are the bindings
that I have a question about.

In Emacs 20, I simply do this:

(substitute-key-definition from to
   minibuffer-local-completion-map global-map)

For example, to bind `C-h' in the minibuffer to command `my-help':

(substitute-key-definition 'help-command 'my-help
   minibuffer-local-completion-map global-map)

I do the same for `self-insert-command', replacing it with `my-self-insert'
for minibuffer maps.

This is very fast in Emacs 20, but in Emacs 22 it is unbearably slow. It
takes about 5 seconds for 10 such key-definition substitutions! I think that
the slowness might be due, in particular, to dealing with the case of
`self-insert-command'.

Someone suggested that I could use `define-key' with [remap...] instead of
`substitute-key-definition'. I'm not sure how to do that, since I use the
OLDMAP arg to `substitute-key-definition'. I tried using the following when
my minor mode is turned on:

(defun my-remap (from to map)
 "Remap command FROM to command TO in keymap MAP."
 (if (boundp 'this-original-command)
     (define-key map [remap `,from] to)                 ; Emacs 22
   (substitute-key-definition from to map global-map))) ; Emacs 20

And similarly when it is turned off, using nil for TO, to remove the binding
from MAP (a minibuffer map).

However, as you can guess, that doesn't work. I haven't expressed that I
want to pick up the `global-map' binding (equivalent of OLDMAP arg to
`substitute-key-definition').

Anyone have a suggestion on how to proceed? What I'm looking for is a fast
way to do more or less what (substitute-key-definition from to map
global-map) does. The performance penalty for using
`substitute-key-definition' is just too big - I need to find something
faster. Any advice would be appreciated.

Re: Question on remapping keys

[Johan Bockgård]

"Drew Adams" <drew.adams@oracle.com> writes:

>      (define-key map [remap `,from] to)                 ; Emacs 22

                       `[remap ,from]

RE: Question on remapping keys

[Drew Adams]

    >      (define-key map [remap `,from] to)
                           `[remap ,from]

Right. Thanks, Johan, but that doesn't completely solve the problem. The
result of remapping is this for minibuffer-local-completion-map:

(keymap
 ...
 (remap keymap
        (scroll-left . my-scroll-left)
        (scroll-right . my-scroll-right)
        (scroll-down . my-scroll-down)
        (scroll-up . my-scroll-up)
        (next-line . my-next-line)
        (previous-line . my-previous-line)
        (help-command . my-help)
        (self-insert-command . my-self-insert))
 ...)

This looks promising, but it seems to work only partially. For instance,

(where-is-internal 'my-scroll-up
                   (list minibuffer-local-completion-map))

returns ([remap scroll-up]), which looks good. `M-x' followed by `C-v' does
invoke `my-scroll-up', but `M-x' followed by [next] (also bound to
`scroll-up' in `global-map') does not invoke `my-scroll-up' - it invokes
`next-history-element', just as in vanilla Emacs.

IOW, apparently not all bindings of `scroll-up' got remapped. I'm looking
for behavior similar to that of `substitute-key-definition':
remap/substitute _all_ bindings. This is especially important since I
apparently have no control over which single binding gets remapped - that
is, only one binding of the command seems to be remapped, and I don't know
how to pick which one.

Similarly,

(where-is-internal 'my-help
                   (list minibuffer-local-completion-map))

returns ([remap help-command]). That suggests that `help-command' was
remapped, but using `C-h' in the minibuffer does not invoke `my-help'.
(Why?)

If I use `substitute-key-definition', providing `global-map' as the OLDMAP
arg, it works perfectly, but the performance is unacceptable. There must be
some way to do something equivalent using command remapping (?).