Emacs 30: Completion Preview Feedback

Emacs 30: Completion Preview Feedback

[Christopher Howard]

Hi, this is just a little unsolicited user feedback on the Completion Preview feature — not meant to be demanding or anything like that.

I think CP is a cool feature, but in the default settings, CP will give a preview even if I have already typed out something that matches, and I find that unnecessarily and frequently distracting. For example, if I type "(mapc", it will give a preview for "(mapcan".

Ideally what I'd like is if the current word already matches something, then there is no preview given.

I set "Completion Preview Exact Match Only" to "on" and that gives me pretty much what I want, since that eliminates the distracting extra previews. A trade off is I don't get any previews for "possible" matches, which could potentionally be useful.

I could I suppose also use an Idle Delay, but personally I hate introducing extra pauses like that into my workflow.

-- 
📛 Christopher Howard
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Re: Emacs 30: Completion Preview Feedback

[Eli Zaretskii]

> From: Christopher Howard <christopher@librehacker.com>
> Date: Fri, 13 Sep 2024 13:37:11 -0800
> 
> Hi, this is just a little unsolicited user feedback on the Completion Preview feature — not meant to be demanding or anything like that.
> 
> I think CP is a cool feature, but in the default settings, CP will give a preview even if I have already typed out something that matches, and I find that unnecessarily and frequently distracting. For example, if I type "(mapc", it will give a preview for "(mapcan".
> 
> Ideally what I'd like is if the current word already matches something, then there is no preview given.

So if you want to type mapcan, you want to see a preview when you type
map, have the preview disappear when you type c, then re-appear again
when you type a?  Won't that flickering be annoying?

> I could I suppose also use an Idle Delay, but personally I hate introducing extra pauses like that into my workflow.

If the delay is short enough, it shouldn't cause any perceptible
pause, I think.

Re: Emacs 30: Completion Preview Feedback

[Eshel Yaron]

Hi Christopher,

Christopher Howard <christopher@librehacker.com> writes:

> Hi, this is just a little unsolicited user feedback on the Completion
> Preview feature — not meant to be demanding or anything like that.

Thanks for that, and let me take the opportunity to explicitly solicit
all such feedback: we'd love to hear your thoughts about the new
Completion Preview mode, and other new features too.

> I think CP is a cool feature, but in the default settings, CP will
> give a preview even if I have already typed out something that
> matches, and I find that unnecessarily and frequently distracting. For
> example, if I type "(mapc", it will give a preview for "(mapcan".
>
> Ideally what I'd like is if the current word already matches something, then there is no preview given.

That makes sense, and we can add an option for enabling such a behavior,
but there are some subtleties to consider: imagine that there are two
completion candidates, "mapc" and "mapcan", and that the completion
table sorts "mapcan" before "mapc".  In this case typing "map" triggers
the completion preview, showing the longer suffix, "can".  You may not
be aware of the existence of a shorter candidate at this point.  Now if
you type "c", then the prefix matches the shorter candidate "mapc", yet
it might be unexpected (and undesirable) if the preview would disappear.

What do you think would be the most useful behavior in such cases?


Cheers,

Eshel

Re: Emacs 30: Completion Preview Feedback

[Christopher Howard]

> That makes sense, and we can add an option for enabling such a behavior,
> but there are some subtleties to consider: imagine that there are two
> completion candidates, "mapc" and "mapcan", and that the completion
> table sorts "mapcan" before "mapc".  In this case typing "map" triggers
> the completion preview, showing the longer suffix, "can".  You may not
> be aware of the existence of a shorter candidate at this point.  Now if
> you type "c", then the prefix matches the shorter candidate "mapc", yet
> it might be unexpected (and undesirable) if the preview would disappear.
>
> What do you think would be the most useful behavior in such cases?
>

Hi, as I ponder this, my preferences lean more and more toward not having *any* non-exact matches. It seems like no matter how it was done, matches that are only "possible" matches are going to generate a lot of noise around point, which is annoying to me. If I really want possible matches, I can always just hit <TAB> to get them to come up in Helm.

So, I guess that makes it a moot issue for me, since I plan to just leave (completion-preview-exact-match-only t) in any case.

Regarding the specific question you asked — I suppose it might depend a bit on the source and handling of completions. More specifically, if the preview was based on history and heuristics, it might be handy to have the preview showing me the option which I have most frequently used in the past. If the preview is something meaningless like alphabetic order, I would just as soon have the preview disappear once I have an exact match on something. It might be nice (or even more distracting? not sure...) if there was some kind of indicator that let me instantly know if what I had typed was in fact an exact match by itself.

-- 
Christopher Howard