bug#36454: 26.2.90; feature request - Insert char by hex tab completion or C-x 8 RET ffe <TAB>

[Eli Zaretskii <eliz@gnu.org>]

> Date: Thu, 18 Jul 2019 16:15:23 +0000 (UTC)
> From: Drew Adams <drew.adams@oracle.com>
> Cc: mrsebastianurban@gmail.com, larsi@gnus.org, van@scratch.space,
>         36454@debbugs.gnu.org
> 
> > > No, you won't get lots of results.  There's little overlap
> > > in general, even if you type only a few chars.  Certainly
> > > less than you get with function and variable names,
> > > especially those that have common prefixes.
> > >
> > > You'll typically type little to get to a single candidate.
> > 
> > Try "ff" or "fe" for some perspective.
> [...]
> If you really want to be extreme, try just "f"

You are missing the point.  My point is that your example is somewhat
skewed: Unicode codepoints in hex go from 0 to 1fffff, so the number
of possible matches for the initial "ffe" is quite small, to put it
mildly.  Real-life examples might yield one or even two orders of
magnitude more candidates; e.g. "fe" as substring (not just the
leading substring) will gives you more than 500.  Even replacing "ffe"
with "123" will already give 170 just of those that begin with "123".
I hope we agree that wading through 170 completion candidates, let
alone 500, is not very convenient, yes?

Bottom line: IME completing on digits is rarely useful, unless you
assume that the user will type almost all of the digits, leaving just
one or two for completion.  And how probable is it that the user will
know the codepoint up to 1 or 2 last digits, but will not know the
entire codepoint?