Re: Updating *Completions* as you type

[Spencer Baugh]

Eli Zaretskii <eliz@gnu.org> writes:
>> From: sbaugh@catern.com
>> Date: Thu, 12 Oct 2023 19:53:53 -0400
>> 
>> 
>> It would be nice if there was a built-in customization which caused
>> *Completions* to update as you type, as long as that buffer is visible.
>> I imagine such a request has been made before, so what is the obstacle
>> to adding it?
>
> I think we have alternative completion schemes, like ido.el and
> others, which update the list of the completion candidates as you
> type, albeit not in the *Completions* buffer.  Why would we need yet
> another knob in the default completion scheme?

ido-mode only works for files and buffers, not all minibuffer
completion, and is also unmaintained and sometimes buggy besides that.

icomplete-mode (and its derivatives) doesn't work for in-buffer
completion.  Also, it is buggier than the default completion scheme.

>> (Btw, if we had this behavior, it also seems like it would help with
>> another long-time request: asynchronous completion support.  A
>> programmed completion table could internally do something asynchronous
>> and stateful, and accumulate results over time, and return more and more
>> results each time Emacs calls all-completions/try-completion.  If Emacs
>> automatically called all-completions with such a programmed completion
>> table, the resulting behavior would be an acceptable approximation of
>> asynchronous completion, without having to complicate the programmed
>> completion API.)
>
> IIUC what you mean by "asynchronous completion", it is a terrible
> idea.  How can anyone type text without getting immediate feedback for
> what he/she typed?  When I sometimes see this (due to network delays
> or system load or whatever), it is a terrible UX.

By asynchronous completion, I just mean being able to type, and trigger
completion, and have completions appear incrementally as they are
computed, without interfering with you continuing to type.  I don't
think that stops immediate feedback for typing.