From ce9eb3564e7376e4452732aef5229a8461f52a09 Mon Sep 17 00:00:00 2001
From: Karl Berry <karl@freefriends.org>
Date: Mon, 13 Jan 2020 21:30:36 +0000
Subject: l3 (13jan20)

git-svn-id: svn://tug.org/texlive/trunk@53394 c570f23f-e606-0410-a88d-b1316a301751
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+% Copyright 2016 The LaTeX3 Project
+\documentclass{ltnews}
+
+\PassOptionsToPackage{colorlinks}{hyperref}
+
+\usepackage{csquotes}
+\usepackage{hologo}
+\usepackage{ragged2e}
+\usepackage{underscore}
+
+\AtBeginDocument{%
+  \renewcommand*{\LaTeXNews}{\LaTeX3~News}%
+  \RaggedRight
+  \setlength\parindent{1em}%
+}
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+\publicationmonth{November}
+\publicationyear{2016}
+\publicationissue{10}
+
+% Avoid hyphenation of csnames
+\makeatletter
+\protected\edef\cs#1{%
+  \noexpand\path{\@backslashchar#1}%
+}
+\makeatother
+
+\begin{document}
+
+\maketitle
+
+There has been something of a gap since the last \LaTeX3 News, but this does
+not mean that work has not been going on. The Team have been working on a
+number of areas, many of which reflect wider take-up of \pkg{expl3}. There have
+also been a number of significant new developments in the \LaTeX3
+\enquote{sphere} in the last two years.
+
+\section{\pkg{l3build}: Testing \LaTeX{} packages}
+
+Testing has been an important part of the work of the team since they assumed
+maintenance of \LaTeX{} over twenty years ago. Various scripts have been used
+over that time by the team for testing, but these have until recently not been
+set up for wider use.
+
+With the general availability of \hologo{LuaTeX} it is now possible to be sure
+that every \TeX{} user has a powerful general scripting language available:
+Lua. The team have used this to create a new general testing system for \TeX{}
+code, \pkg{l3build}. This \emph{is} designed to be used beyond the team, so is
+now available in \TeX{} Live and \hologo{MiKTeX} and is fully documented.
+Testing using \pkg{l3build} makes use of a normalised version of the
+\texttt{.log} file, so can test any aspect of \TeX{} output (e.g., by using
+\cs{showbox}) or its algorithms (by displaying results in the \texttt{.log}).
+
+Part of the remit for creating \pkg{l3build} was to enable the team to work
+truly cross-platform and to allow testing using multiple \TeX{} engines
+(earlier systems were limited to a single engine, normally \eTeX{}). The new
+testing system means we are in a much stronger position to support a variety of
+engines (see below). It has also enabled us to give useful feedback on
+development of the \hologo{LuaTeX} engine.
+
+As well as the core capability in testing, \pkg{l3build} also provides a
+\enquote{one stop} script for creating release bundles. The script is
+sufficiently flexible that for many common \LaTeX{} package structures, setting
+up for creating releases will require only a few lines of configuration.
+
+In addition to the documentation distributed with \pkg{l3build}, the project
+website~\cite[publications in 2014]{project-publications} contains some
+articles, videos and conference presentations that explain how to use
+\pkg{l3build} to manage and test any type of (\LaTeX{}) package.
+
+\section{Automating \pkg{expl3} testing}
+
+As well as developing \pkg{l3build} for local use, the team have also set up
+integration testing for \pkg{expl3} using the Travis-CI system. This means that
+\emph{every} commit to the \LaTeX3 code base now results in a full set of tests
+being run. This has allowed us to significantly reduce the number of occasions
+where \pkg{expl3} needs attention before being released to CTAN.
+
+Automated testing has also enabled us to check that \pkg{expl3} updates do not
+break a number of key third-party packages which use the programming
+environment.
+
+\section{Refining \pkg{expl3}}
+
+Work continues to improve \pkg{expl3} both in scope and robustness. Increased
+use of the programming environment means that code which has to-date been
+under-explored is being used, and this sometimes requires changes to the code.
+
+The team have extended formal support in \pkg{expl3} to cover the engines
+p\TeX{} and up\TeX{}, principally used by Japanese \TeX{} users. This has been
+possible in part due to the \pkg{l3build} system discussed above.
+Engine-dependent variations between \hologo{pdfTeX}, \hologo{XeTeX},
+\hologo{LuaTeX} and (u)p\TeX{} are now well-understood and documented. As part
+of this process, the \enquote{low-level} part of \pkg{expl3}, which saves all
+primitives, now covers essentially all primitives found in all of these
+engines.
+
+The code in \pkg{expl3} is now entirely self-contained, loading no other
+third-party packages, and can also be loaded as a generic package with plain
+\TeX{}, \emph{etc.} These changes make it much easier to diagnose problems and
+make \pkg{expl3} more useful. In particular it can be used as a programming
+language for generic packages, that then can run without modifications under
+different formats!
+
+The team have made a range of small refinements to both internals and
+\pkg{expl3} interfaces. Internal self-consistency has also been improved, for
+example removing almost all use of \texttt{nopar} functions. Performance
+enhancements to the \pkg{l3keys} part of \pkg{expl3} are ongoing and should
+result in significantly faster key setting. As keyval methods are increasingly
+widely used in defining behaviours, this will have an impact on compile times
+for end users.
+
+\section{Replacing \cs{lowercase} and \cs{uppercase}}
+
+As discussed in the last \LaTeX3 News, the team have for some time been keen to
+provide new interfaces which do not directly expose (or in some cases even use)
+the \TeX{} primitives \cs{lowercase} and \cs{uppercase}. We have now created a
+series of different interfaces that provide support for the different
+conceptual uses which may flow from the primitives:
+\begin{itemize}
+  \item For case changing text, \cs{tl_upper_case:n}, \cs{tl_lower_case:n},
+    \cs{tl_mixed_case:n} and related language-aware functions. These are
+    Unicode-capable and designed for working with text. They also allow for
+    accents, expansion of stored text and leaving math mode unchanged.  At
+    present some of the interface decisions are not finalised so they are
+    marked as experimental, but the team expect the core concept to be stable.
+  \item For case changing programming strings, \cs{str_upper_case:n},
+    \cs{str_lower_case:n} and \cs{str_fold_case:n}. Again these are
+    Unicode-aware, but in contrast to the functions for text are not
+    context-dependent. They are intended for caseless comparisons, constructing
+    command names on-the-fly and so forth.
+  \item For creating arbitrary character tokens, \cs{char_generate:nn}. This
+    is based on the \cs{Ucharcat} primitive introduced by \hologo{XeTeX}, but
+    with the ideas extended to other engines. This function can be used to
+    create almost any reasonable token.
+  \item For defining active characters, \cs{char_set_active_eq:NN} and
+    related functions. The concept here is that active characters should be
+    equivalent to some named function, so one does not directly define the
+    active character.
+\end{itemize}
+
+\section{Extending \pkg{xparse}}
+
+After discussions at TUG2015 and some experimentation, the team have added a
+new argument type, \texttt{e} (\enquote{embellishment}), to \pkg{xparse}.
+This allows arguments similar to
+\TeX{} primitive sub- and superscripts to be accepted. Thus
+\begin{verbatim}
+\DeclareDocumentCommand\foo{e{^_}}
+  {\showtokens{"#1"}}
+\foo^{Hello} world
+\end{verbatim}
+will show
+\begin{verbatim}
+"{Hello}{-NoValue-}".
+\end{verbatim}
+
+At present, this argument type is experimental: there are a number of models
+which may make sense for this interface.
+
+\section{A new \cs{parshape} model}
+
+As part of development of \pkg{l3galley}, Joseph Wright has proposed a new
+model for splitting up the functions of the \cs{parshape} primitive into three
+logical elements:
+\begin{itemize}
+  \item Margins between the edges of the galley and the paragraph (for example
+    an indented block);
+  \item Cut-out sections running over a fixed number of lines, to support
+    \enquote{in place} figures and so forth;
+  \item Running or single-paragraph shape.
+\end{itemize}
+
+There are additional elements to consider here, for example whether lines are
+the best way to model the length of shaping, how to handle headings, cut-outs
+at page breaks, \emph{etc.}
+
+
+\section{Globally optimized pagination of documents}
+
+Throughout 2016 Frank Mittelbach has worked on methods and algorithms for
+globally optimizing the pagination of documents including those that contain
+floats. Early research results have been presented at Bacho\TeX{} 2016, TUG
+2016 in Toronto and later in the year at \mbox{DocEng'16}, the ACM Symposium on
+Document Engineering in Vienna. A link to the ACM paper (that allows a download
+free of charge) can be found on the project
+website~\cite{project-publications}. The site also holds the speaker notes from
+Toronto and will host a link to a video of the presentation once it becomes
+available.
+
+The framework developed by Frank is based on the extended functionality
+provided by \hologo{LuaTeX}, in particular its callback functions that allow
+interacting with the typesetting process at various points. The algorithm that
+determines the optimal pagination of a given document is implemented in {Lua}
+and its results are then used to direct the formatting done by the \TeX{}
+engine.
+
+At the current point in time this a working prototype but not yet anywhere near
+a production-ready system. However, the work so far shows great potential and
+Frank is fairly confident that it will eventually become a generally usable
+solution.
+
+\section{Looking forward}
+
+The \hologo{LuaTeX} engine has recently reached version~1.0. This may presage a
+stable \hologo{LuaTeX} and is likely to result in wider use of this engine in
+production documents.If that happens we expect to implement some of the more
+complex functionality (such as complex pagination requirements and models) only
+for \hologo{LuaTeX}.
+
+\begin{thebibliography}{10}
+  \raggedright
+  \bibitem{project-publications}
+    Links to various publications by members of the \LaTeX{} Project Team.
+    \newblock \url{https://www.latex-project.org/publications}.
+\end{thebibliography}
+
+\end{document}
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