IronPort-PHdr: =?us-ascii?q?9a23=3AZd9RuRywCj2ryRDXCy+N+z0kezQntrPoPwUc9p?=
               =?us-ascii?q?sgjfd0f7+++4j5ZRyEt+9giFbYG5jd6rdEhuvavqTqVHYPp5qM4zgZaJIZcR?=
               =?us-ascii?q?gDhI0NmhA4RtafABj1NvfsbGo/HdheWVtv9nq7GUxcBMvuIkXIpX+/5iJUHQ?=
               =?us-ascii?q?/wZkJuPuqgIofJlIys0vyqvZjaYgFGnj24NL1oJRO16wDQqtUbhYFrIaYZzh?=
               =?us-ascii?q?LVr2sNY/5Rx25jORSUhRmvrtyo8stF9CJd8+kk69YGUaj+ePEgSqdECT09L2?=
               =?us-ascii?q?0vzMbssBTPXE2D730AXyMan0MSUTLI5xz7QJr99xDCmLEhhnu8Osv7BfAuVD?=
               =?us-ascii?q?Cr/uF2Th6tiCoGOzM9+mzNhYp8gfATphXpvBF5z4POBePdfPNjYqPQe88bTm?=
               =?us-ascii?q?tdT45QUSJGGIa1c4oICaIII+9Zq4D3o1ZGowG5AEGgA+bmyzkAgXGTv+Vy3f?=
               =?us-ascii?q?4oFwKA2Q08A98Kun3frP3xPbsfQaWt1q7KwD7fKfRM1na16YTFdAwgveDZRa?=
               =?us-ascii?q?h5Iq+zgQEkEwLIiEnVqJSwZmzLkL5d9TXHqbMwCbHnkWMspgBvryL63Moog5?=
               =?us-ascii?q?iPm4QUj1DJ9Cl0xIw4P9L+REMoBLzsWJZWqSyeMJN7B804RGQ98iggw7sF/5?=
               =?us-ascii?q?u6YDQHzJ4uzB73b/WbfpjN+gjkVuuaPXF/nn0vK9fdz16itFOtzOHxTJz+3k?=
               =?us-ascii?q?xDqCkDl9jQqn0J3RXY6uCDQ+dw7gK5wzGN2gvPrOZeLgpn8MiTY45kybk2mJ?=
               =?us-ascii?q?0JtE3FFSKjg0T6gpidcUA88/Sp4eDqO++0nJKXOo5qhw27CZwAxpTiU9wxKR?=
               =?us-ascii?q?NGH3KW/e2tkqDl/Aj5TbRGg/k8n7PW9pzXd4wXoauwAgkd1YhGiV73AS2v1t?=
               =?us-ascii?q?demHgbMF9BchuMj6DtMk3DMLXgF/C9jl+w1jBxyLjKM6bgDZPEMnXY2O6+I/?=
               =?us-ascii?q?AnuwgBlExqnYw6hdocA6pJOP/pX07tqNHURgQ0NQC52aevCdlw0J8fRXPaB6?=
               =?us-ascii?q?aYNK3Itlrbg4Bna+KIZYITpHP8M618uKCo1y9/xANbJPn1jtMNZXu1H+prOR?=
               =?us-ascii?q?CDbH7lk5EcF2ZPvgc/QOHuglCYXnhfaiXXPep06zclBYahFYqGSJqqhenL0j?=
               =?us-ascii?q?2yGJ4QY2FaFl2IG37jd62AUusBeGeKOMhjnzcYE7+7RMVysHPm/B+/0LdhIu?=
               =?us-ascii?q?fOr2cWr5vl155w5vHPmBU4/Dd0J8CUz2ydCnlumWEFTCNw27pw6x8YqB/Lwe?=
               =?us-ascii?q?1zhPpWEsZW7vVCX1IhNJLS+Od9Dsj7RgPLetraAEbjWNitBis9C84g29JbKV?=
               =?us-ascii?q?goAM2s11qQukjiS69QjbGAA4Y4t77Rz2Skbdgo0G7IjeEknxFjS89LfzT81J?=
               =?us-ascii?q?Ry/AXSGYPF1n6huf3xLPY62yjAvCeZwG6HrQdFVg81UajEUX0bbEbMopL16x?=
               =?us-ascii?q?GKSbjmErkhPgZbrKzKYqJXdt3ki0lHT/b/KZzfZWy2gWK5GRePwPuFcoPrf2?=
               =?us-ascii?q?wX2CiVBlIDlkgf+nOPNA52ASnEwSqWFDt1CVfmeF/h68F1r3a2Ql5ywwiMc0?=
               =?us-ascii?q?An27f0sh8ZiPqASu8Ci7IJvCByzlc8VF253t/QF5+Bv184I/saO4N7vQsBjD?=
               =?us-ascii?q?KF5ERnM5etLr5vnAsEfgB+rgXz0RQyCohBncUupn4ww0x+JPH9shsJejWG0J?=
               =?us-ascii?q?T3IrCSJHP1+UXlZbTf3FKY1deK5qoL4v0zq33ntR2kBg866XJl3tJJlXyG6d?=
               =?us-ascii?q?+ZaWhaGYK0SUsx+xVg8vvCZTIh4orPyXB2GaKztzLOypQlDe05x1Cscp0MVc?=
               =?us-ascii?q?HMXB+3GMocCc+0LeUskFX8dRMIMtdZ86ssNt+nff+Lgf/5DKNbhDujyF9/zs?=
               =?us-ascii?q?V420OI+TB7T7eZjZIM3/yImxOdUDXxh0vntdr4y9kdOWMiW1GnwC2hP7Z/I7?=
               =?us-ascii?q?VodN9aW2OnP8Cng81kgJzgUGIe80SsVQtfhZ2ZPCGKZlm45jV+kEQapXv+xn?=
               =?us-ascii?q?mzyDl5nyBvoqOZwCGIz+mwLBc=3D?=
References: <5630732433921446.WA.kellysmith12.21gmail.com@listserv.uni-heidelberg.de>
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:60.0)
            Gecko/20100101 Thunderbird/60.5.0
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 8bit
Message-ID:  <9636d025-7503-e83c-6982-dc4e38b85a54@latex-project.org>
Date:         Tue, 12 Feb 2019 17:13:43 +0100
Reply-To:     Mailing list for the LaTeX3 project
              <LATEX-L@LISTSERV.UNI-HEIDELBERG.DE>
Sender:       Mailing list for the LaTeX3 project <LATEX-L@LISTSERV.UNI-HEIDELBERG.DE>
From:         Frank Mittelbach <frank.mittelbach@LATEX-PROJECT.ORG>
Subject: Re: Text Commands in XeLaTeX and LuaLaTeX
To:           LATEX-L@LISTSERV.UNI-HEIDELBERG.DE
In-Reply-To:  <5630732433921446.WA.kellysmith12.21gmail.com@listserv.uni-heidelberg.de>
Precedence: list
Envelope-To: <rainer.schoepf@gmx.net>
Status: R

Am 14.01.19 um 07:15 schrieb Kelly Smith:

>> of course this is way before the event of unicode or xetex/luatex ...
> 
> As for XeTeX and LuaTeX, it appears that UTF-8 text doesn’t get converted
> to an internal representation, according to some quick experiments I tried.

in some sense I would love to make that happen (as there are also 
advantages to it) but it would come at a high cost

  - loss of speed (somewhat)
  - impossibility to use utf8 chars in csnames, eg in luatex you can do

    \newcommand\Füße{}

     as long as the chars are of \catcode 11, once they are active they 
can't be used in this way and while I personally wouldn't mind, I can 
understand that depending on your language you rather want that to be 
possible.

The second point really means that it is a no-go

> I guess that it would be impractical to set up automatic conversions
> for such a large character set.

There is that.

> And, as you said, since the UTF-8 will
> survive reading and writing to and from files, an internal representation
> isn’t critical.

The downside is that you simply don't know if the character will typeset 
correctly in a given situation, as that approach assumes that everything 
is unicode and that there is something at the other end when you ask the 
font to render the utf8 char--- as that is not necessarily true you may 
end up with tofu in other words a certain step backwards from the 
situation we had in that respect in 8bit

> When running on XeTeX or LuaTeX, is there an interface for getting the
> Unicode character(s) represented by a text command? (e.g. \"{a} -> ä,
> useful for string comparison). I suppose one could easily achieve that by
> locally redefining all the text commands?

Not necessary, you just need to process the definitions in the right 
state, eg

\typeout{ä \"w}

\makeatletter
\protected@edef\foo{ä \"w}

\show\foo

will give you this as output:

ä \"w
 > \foo=macro:
->ä \"w.
l.14 \show\foo

cheers
frank