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Message-ID:  <Pine.LNX.4.62.0511142004030.30057@pcl321.mppmu.mpg.de>
Date:         Mon, 14 Nov 2005 20:11:34 +0100
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From: Peter Breitenlohner <peb@MPPMU.MPG.DE>
Subject: Re: LaTeX3 access, pdfTeX extensions, &c.
To: LATEX-L@LISTSERV.UNI-HEIDELBERG.DE
In-Reply-To:  <17272.53237.920872.634154@pussy.r.npc.de>
Precedence: list
Status: R

On Mon, 14 Nov 2005, Joachim Schrod wrote:

>>>>>> "WR" == Will Robertson <will@GUERILLA.NET.AU> writes:
>
> WR> The token stream won't change retrospectively, so in theory it
> WR> should be able to be examined.
>
> But it does change. That's the whole point of macros, to change the
> token stream.
>
> With a definition of
>
>    \newcommand\a[1]{f1\b{#1}}
>    \newcommand\b[2]{\par #2 #1}
those two probably ought to be \renewcommand instead of \newcommand
>
> and an input of
>
>    ab\a12
>
> this results in the following token stream [*]

Although irrelevant for the conclusion, you (JS) should have gotten this
right:

>
>    (char "a") (char "b") (cseq "a") (other "1") (other "2")
>
> which is in turn transformed into the token stream
>
>    (char "a") (char "b") (cseq "b") (bgroup "{") (other "1")
>    (egroup "}") (other "2")
should read
    (char "a") (char "b") (char "f") (other "1") (cseq "b")
    (bgroup "{") (other "1") (egroup "}") (other "2")
>
> and then into the token stream
>
>    (char "a") (char "b") (cseq "par") (other "2") (other "1")
should read
    (char "a") (char "b") (char "f") (other "1") (cseq "par")
    (other "2") (space " ") (other "1")
>
> Which of those do you want to keep? There are good arguments for all
> of them.
> ........

Peter Breitenlohner <peb@mppmu.mpg.de>