Re: Usability suggestion : completion for M-:

[Juri Linkov]

>> I think the only problem preventing this change is one completion message
>> that overwrites the minibuffer when TAB doesn't find a completion.
>> I propose the patch below similar to the patch I proposed for the
>> shell command minibuffer completion.
>>
>> When this is fixed, it makes sense to allow TAB to complete a lisp
>> symbol part of the eval-expression minibuffer in the same way as TAB
>> will allow completion of command name and file name parts of the
>> shell-command minibuffer.
>
> The discussion seems to have been badly sidetracked.
>
> The patch looks good.  Please install it.

The first part of the patch is installed now.  But I still see
no unanimous consensus on what command to bind to TAB in
read-expression-map.  Currently it inserts just a tab character,
and this is useless in the minibuffer.

I think we could add a new command `lisp-indent-or-complete'
that will complete a Lisp symbol if the character preceding point
is symbol-constituent, or indent line or region otherwise.
And bind TAB in read-expression-map to this command.

Note that I don't propose to bind TAB in emacs-lisp-mode to this
command by default.  So no changes in emacs-lisp-mode (though it will
be available to easily rebind TAB in .emacs to everyone who likes this
behavior).

-- 
Juri Linkov
http://www.jurta.org/emacs/