completion-auto-help

[Drew Adams]

1. Question:

The doc string for `completion-auto-help' says this:

 Non-nil means automatically provide help for invalid completion input.

The Elisp manual says this about it:

 If this variable is non-`nil', the completion commands
 automatically display a list of possible completions whenever
 nothing can be completed because the next character is not
 uniquely determined.

In neither case are different non-nil values distinguished. So, I don't
understand this code in complete.el:

(if (or (eq completion-auto-help t)
        (and completion-auto-help
             (eq last-command this-command))
        (eq mode 'help))

The second arg to `or' can only be evaluated if `completion-auto-help' is
not `t', and that second arg tests whether it is non-nil.

Am I missing something - is there some special treatment somewhere for
non-nil, non-t value? (That's what the second arg seems to be doing.) I see
no other occurrences of `completion-auto-help' anywhere in the Lisp code
that distinguish different non-nil values.


2. New feature proposal - How about allowing for an
"always-display-*Completions*' behavior:

 - t means what it means now
 - nil means what it means now
 - other means this:

Display *Completions* right from the beginning (empty minibuffer input).
Display it as long as the minibuffer contents match more than one
completion.

IOW, with this value, the user would not need to hit `TAB' to display
*Completions*. (S)he would see the list of completions whenever there are
more than one. There is currently no way to make `completing-read',
`read-file-name' etc. display *Completions* from the outset.