Re: Updating *Completions* as you type

[Juri Linkov]

>>>> This is what I believe they should do: we add a category,
>>>> and they support it as well.
>>>
>>> OK, I'm fine with that, but when we do that, I think the per-table
>>> option should override the per-category option.
>>
>> I agree that the per-table option should override the per-category option,
>> but see no way to distinguish customized values from hard-coded ones
>> without trying to turn all hard-coded values into options.
>
> Right.  I guess my position is that there's not that many hard-coded
> display-sort-functions (only 5 in core Emacs), so turning them all to
> options is fine.

And my position is that simpler to add a category or some identifier.
So we need more opinions.

>> display-buffer has a similar problem, but the difference is that
>> it's possible to identify a buffer by its name and use a regexp
>> to match buffer names.  Whereas for completing-read it's not easy
>> to identify a completion table.  A category matches a set of
>> completion tables, so maybe we need another identification
>> for individual tables?
>
> True, that would help.  Maybe the function symbol for the completion
> table?  Tables are usually lambdas today, but maybe we could make it
> easy to use a defun'd function instead, which would be very good for
> comprehensibility in general IMO.

Turning lambdas into symbols looks good, this is like the existing
'help--symbol-completion-table'.