RE: migrating from ido to icicles

[Drew Adams]

> >> "M-SPC runs the command icicle-prefix-word-complete, which is an
> >> interactive compiled Lisp function in `icicles-mcmd.el'."
>
> I was able to successfully bind M-SPC to 
> icicle-prefix-word-complete by
> customizing icicle-word-completion-keys.

It is already bound to M-SPC, as you indicated above.
Perhaps you meant M-TAB.

> However the docs for icicle-word-completion-keys suggest that 
> I can also bind SPC if I wanted.  That actually sounds better
> because I can't remember the last time I tried to complete a
> filename with a space in it.

I don't recommend that, but you are welcome to do it.  Icicles completion works
for all kinds of things, many of which contain space chars.

The point of binding SPC to self-insertion is to, well, make it easy to insert a
space, rather than having to use `C-q SPC'.  Likewise, for `?' and `C-j'
(newline).

> But no matter what I put in that field, SPC wouldn't trigger
> icicle-prefix-word-complete, it was still bound to icicle-self-insert.

You need to do three things:

1. What you did: add the SPC binding for `icicle-word-completion-keys'/

2. Remove the SPC binding to `icicle-self-insert' from option
`icicle-completion-key-bindings'.

3. Toggle Icicle mode twice (exit and re-enter): M-x icy-mode M-x icy-mode.  (Or
restart Emacs.)

Vanilla Emacs binds SPC to prefix word completion.  Icicles binds it, in the
default value of `icicle-completion-key-bindings', to self-insertion insertion.
Likewise, `?' and `C-j'.

As I said, Icicles is used for completing lots of things besides just commands
and file names, and it generally makes sense to have ` ', `?', and `C-j' be
self-inserting.  But you can easily customize this away.

> There's one other odd behavior I've been noticing.  Even though I have
> icicle-expand-input-to-common-match-flag

That option name should be without the `-flag'.  Long ago the option was a
Boolean and its name had the suffix `-flag'.  Since you mention a value of `1'
you clearly do not have an older version of Icicles where the option had that
former name.

> set to 1 (only expand when
> using tab or s-tab), I am finding that I do get input inserted for me
> as I'm trying to type, and it ends up mixing my input with its own,
> resulting in bad input in the minibuffer.
> 
> For example, if the directory I'm completing in has 3 files, fop fob bar
> if I quickly type 'fo' what appears in the minibuffer is 
> 'foo'.
>
> I think that's because it's trying to expand the common match, since all the
> files that have 'f' also have 'fo'.

That is not what Icicles calls expansion to the common match.  It is what
Icicles calls incremental completion.

This explains common-match expansion:
http://www.emacswiki.org/emacs/Icicles_-_Expanded-Common-Match_Completion.

This explains incremental completion:
http://www.emacswiki.org/emacs/Icicles_-_Icompletion

You can cycle/toggle either of these during completion, to see the differences.
See the doc strings of `icicle-expand-input-to-common-match' and
`icicle-incremental-completion'.

HTH.