Re: completion-auto-help

[Stefan Monnier]

>     complete.el extends the meaning of the variable so that a non-nil non-t
>     value means "show the help but only on the second attempt to complete".
>     I.e. if TAB finds nothing to complete, the first TAB will just
>     say "[Next
>     char not unique]" without bringing up the *Completions* buffer, and the
>     second TAB will then bring up the *Completions* buffer.
>     It happens to be my favorite behavior.

> Thanks. I knew about that behavior, but I couldn't make out the related use
> of completion-auto-help.

> I still don't see it in complete.el (it is only tested there, never bound),
> and I don't see it in C code either. Where is `completion-auto-help's
> non-nil, non-t value bound?

completion-auto-help is a user variable.  It's only meant to be changed in
the .emacs file.

> If it is only a user who sets such a value, then shouldn't the non-nil,
> non-t behavior be documented for the user option? I don't see that, as I
> mentioned.

It's not documented, because there's no place to document it:
completion-auto-help is part of the basic completion facilities, whereas the
added behavior is only provided in complete.el which is a separate package.

> I proposed `eager' _without_ the automatic update after each keystroke, in
> order to allow that as an additional (separate) option. I think that would
> be better. Some people (or some functions) might like to display the list of
> candidates right from the beginning, as a kind of menu, but prefer to update
> it only upon demand (via `TAB'), not automatically at each keystroke. Some
> people might find the automatic list updating to be distracting (I find it
> very helpful, personally).

I'd wait to see people complaint about one of the two behaviors before
providing both.

> gets called inside `completing-read', upon insertion, but I see no way to
> get `completing-read' to display *Completions* without any user action.

IIRC you can do it from minibuffer-setup-hook.


        Stefan