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              <LATEX-L@URZ.UNI-HEIDELBERG.DE>
Organization: Broadband Network Design
Date:         Wed, 21 Oct 1998 21:08:28 +0000
From: Hubert Gaesslein <Gaesslein@BNED.COM>
Sender: Mailing list for the LaTeX3 project
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To: Multiple recipients of list LATEX-L
              <LATEX-L@URZ.UNI-HEIDELBERG.DE>
Subject:      Re: Users dropping into TeX
Status: R

William F. Hammond <hammond@CSC.ALBANY.EDU>
on Wed, 21 Oct 1998 09:01:47 -0400 wrote:

> But my original question was motivated by several lines from
> "ltx3info.tex" and my wondering whether these lines were durable
> for the LaTeX-3 future.
>
> Here are clips of a "newenvironment" and a "newcommand":
>
> %%%%% clip
> \newenvironment{citations}{%
>    \list{}{%
>       \renewcommand{\makelabel}[1]{\normalfont\itshape ##1}%
>    }%
> }{%
>    \endlist
> }
> %%%%% clip
> \newcommand{\AmSLaTeX}{$\mathcal A$\lower.4ex\hbox{$\!\mathcal
>                                               M\!$}$\mathcal S$-\LaTeX}
> %%%%% endclips
>
> (I do not see why "citations" could not have been done entirely in
> Lamport LaTeX.  (I am unclear what "list" and "endlist" are.))

A LaTeX environment "foo" is basically implemented as a pair of
commands "\foo" and "\endfoo".
The construct

        \begin{foo}
        ...
        \end{foo}

will be translated to something like

        \begingroup
            \foo
                ...
            \endfoo
        \endgroup

plus some extra code to check whether such an environment is defined
at all and whether the names given as arguments to \begin and \end
match each other.

Many of LaTeX's environments (e.g., enumerate, quotation, description,
verse) are based on the "list" environment (or its cousin "trivlist");
i.e., in the above definition

        \begin{list} ... \end{list}

could've been used as well---the only differences would have been
an extra (redundant) level of grouping and some performance overhead.

> In the "AmSLaTeX" macro I believe that "lower" and "hbox" are
> ordinary TeX.

Yupp. These are TeX primitives (built-in, not macros) --- unless
somebody comes along and redefines them, of course.

> Will this usage survive?

Probably not. According to the demos/preview of LaTeX3 published
last spring (1), *lots* of things are going to change. (The TeXbook
may well become useless for us humble package writers ...)

(1) CTAN:macros/latex/packages/expl3/


Hubert Gaesslein
<Gaesslein@BNeD.com>