RE: propose adding Icicles to Emacs

[Drew Adams]

> In the vanilla Emacs `customize-apropos-faces', you must provide a regexp
> once and for all, with RET - there is no completion of face names
> available, and no way to rectify your regexp without starting over.
>
> This is a good example of the general advantage of regexp matching on the
> fly, and the advantage of providing input by completion whenever possible.

I might add that once you have the ability to type and change the regexp to
match dynamically, there is less raison d'etre for these
`customize-apropos-*' commands. An Icicles user would simply use
`customize-face' and so on, instead.

Well, not really. A multi-command version of each would first need to be
defined, so that `C-RET' etc. could DTRT. With RMS's proposed
`call-interactively' tweak, this step would presumably be unnecessary.

With Icicles (without RMS's `call-interactively tweak), here is, for
example, a definition of a multi-command `customize-face':

(defun icicle-customize-face (face)
  "Customize face FACE."
  (interactive (list (let ((icicle-candidate-action-fn 'customize-face))
                       (read-face-name "Customize face: "))))
  (customize-face face))

Actually, because `customize-face' moves the frame focus to the Customize
frame, and you want to keep the focus on the minibuffer frame (which might
be a different frame) until you're done completing and acting on candidates,
this is what you really need:

(defun icicle-customize-face (face)
  "Customize face FACE."
  (interactive
   (list (let ((icicle-candidate-action-fn
                (lambda (x)
                 (customize-face x)
                 (select-frame-set-input-focus
                  (window-frame (minibuffer-window))))))
           (read-face-name "Customize face: "))))
  (customize-face face))

Also, there is the inconvenience that acting on all matching face names
would, in this case, open a separate Customize buffer for each. So, this is
not exactly equivalent to `customize-apropos-faces', and not quite as
convenient for customizing several faces.

Still, it does point out that having the ability to:

 1) type a regexp at any time to match candidates and
 2) act on any or all candidates (C-RET or C-!)

means that commands such as `(customize-)apropos-*' that ask for a regexp up
front are not quite so necessary.

Instead of entering a regexp once and for all to the prompt of such
commands, you can type the same regexp to any multi-command that acts on
such a candidate - in this case, a multi-command version of
`customize-face'.

And you can change that regexp on the fly, to correct it or to act on
different candidates. In `icicle-occur', for instance, you just start typing
a regexp and the matching lines become the search targets as you type - edit
the regexp and the search targets change (similar to `isearch-*-regexp').

An added specific advantage for `icicle-customize-face' is that, by using
`read-face-name' and `customize-face', you can see (WYSIWYG) the faces you
might choose to customize, in *Completions*. Even with the tweak to
`read-face-name' that provides this behavior generally,
`customize-apropos-faces' still shows plain face names as candidates,
because it does not use `read-face-name'.

Another advantage is of course on-the-fly help for individual faces: during
completion, `C-M-mouse-2' or `C-M-RET' on a face-name candidate shows the
face's doc string.