From 1b316273c7c37f4c051ace6bc04cd8bfe55809e7 Mon Sep 17 00:00:00 2001 From: Karl Berry Date: Thu, 23 Dec 2010 23:34:46 +0000 Subject: sphack is back (23dec10) git-svn-id: svn://tug.org/texlive/trunk@20842 c570f23f-e606-0410-a88d-b1316a301751 --- Master/texmf-dist/doc/latex/sphack/sphack-doc.pdf | Bin 0 -> 241052 bytes Master/texmf-dist/doc/latex/sphack/sphack-doc.tex | 115 ++++++++++++++++++++++ 2 files changed, 115 insertions(+) create mode 100644 Master/texmf-dist/doc/latex/sphack/sphack-doc.pdf create mode 100644 Master/texmf-dist/doc/latex/sphack/sphack-doc.tex (limited to 'Master/texmf-dist/doc') diff --git a/Master/texmf-dist/doc/latex/sphack/sphack-doc.pdf b/Master/texmf-dist/doc/latex/sphack/sphack-doc.pdf new file mode 100644 index 00000000000..bbd9c827041 Binary files /dev/null and b/Master/texmf-dist/doc/latex/sphack/sphack-doc.pdf differ diff --git a/Master/texmf-dist/doc/latex/sphack/sphack-doc.tex b/Master/texmf-dist/doc/latex/sphack/sphack-doc.tex new file mode 100644 index 00000000000..3c685d5c407 --- /dev/null +++ b/Master/texmf-dist/doc/latex/sphack/sphack-doc.tex @@ -0,0 +1,115 @@ +\documentclass[pagesize=auto]{scrartcl} + +\usepackage{fixltx2e} +\usepackage{etex} +\usepackage{lmodern} +\usepackage[T1]{fontenc} +\usepackage{textcomp} +\usepackage{microtype} +\usepackage{hyperref} + +\newcommand*{\mail}[1]{\href{mailto:#1}{\texttt{#1}}} +\newcommand*{\pkg}[1]{\textsf{#1}} +\newcommand*{\cs}[1]{\texttt{\textbackslash#1}} +\makeatletter +\newcommand*{\cmd}[1]{\cs{\expandafter\@gobble\string#1}} +\makeatother + +\addtokomafont{title}{\rmfamily} + +\title{The \pkg{sphack} package\thanks{This manual corresponds to \pkg{sphack.sty}~v1.0, dated~22 May 1998.}} +\author{Oliver Pretzel\thanks{\mail{o.pretzel@ic.ac.uk}}} +\date{22 May 1998} + + +\begin{document} + +\maketitle + +\noindent +Standard \LaTeX\ uses the macros \cmd{\@bsphack}, \cmd{\@esphack}, and \cmd{\@Esphack}, for +inserts into the text that should be invisible. So, for instance a space +before and after a \cmd{\label} command should not result in two spaces in the +output. + +\LaTeX\ deals with this as follows +% +\begin{itemize} +\item in maths mode do nothing, +\item in horizontal mode restore the space factor, +\item if the last thing on the list was a space + add \cmd{\ignorespaces} (and (\cmd{\global})\cmd{\ignore\-true} at the end of an environment), +\item in vertical mode do nothing. +\end{itemize} + +Doing nothing in maths mode is (nearly) harmless because maths mode does its +own spacing (and anyway hidden commands will usually appear only at the start +or end of maths). + +Doing nothing in vertical mode is not harmless. Many invisible commands such +as \cmd{\index} may insert delayed write commands into \TeX's output (so that page +numbers are correctly calculated). These commands can cause vertical space to +accumulate, and may cause a page break; \cmd{\index} is a particular problem in +\LaTeX2.09 since it inserts a delayed write if an index is actually being built +(\cmd{\makeindex} in preamble) but does nothing otherwise. That can change the page +breaks in a document. + +It is not possible to solve this problem completely in \LaTeX\ because \TeX\ does +not remove things from the main vertical list once they have been +contributed. So \LaTeXe\ makes \cmd{\index} insert something into the vertical +list whether the index is being written or not. That has the virtue of +consistancy, but is far from ideal. For instance, an \cmd{\index} immediately after +an \cmd{\item} can cause the page to break between the item label and content. + +\pagebreak[2] + +The code in the \pkg{sphack} package remedies this fault and other common anomalies so that commands +are nearly always invisible in vertical mode as well. It works as follows: +% +\begin{itemize} +\item Rename \LaTeX's dimension \cmd{\@savsk} to \cmd{\@savdim} set a new skip \cmd{\@savsk} + (because we need a true skip and a dimension in vertical mode) + +\item \cmd{\@bsphack} (at start of invisible command) + \begin{itemize} + \item in hmode (non-math) + \begin{enumerate} + \item store spacefactor in \cmd{\@savsf} + \item store lastskip in \cmd{\@savsk} (used to test whether space already present) + \end{enumerate} + + \item in vmode + \begin{enumerate} + \item store lastpenalty in \cmd{\@savsf} + \item store lastskip in \cmd{\@savsk} (used for movement) + \item store previous depth in \cmd{\@savdim} + \item skip back \cmd{\lastskip} + \end{enumerate} + \end{itemize} + +\item \cmd{\@esphack} (at end of invisible command) + \begin{itemize} + \item in hmode (non-math) + \begin{enumerate} + \item set spacefactor = \cmd{\@savsf} + \item if \cmd{\@savsk} > \cmd{\z@} \cmd{\ignorespaces} + \end{enumerate} + + \item in vmode + \begin{enumerate} + \item if in a label, or just after section heading, or if \cmd{\@nobreak}\\ + insert infinite penalty, (to prevent a page break)\\ + else insert penalty \cmd{\@savsf}\\ + endif + \item set previous depth = \cmd{\@savdim} + \item skip \cmd{\@savsk} + \end{enumerate} + \end{itemize} +\end{itemize} +% +Just as in standard \LaTeX, \cmd{\@Esphack} is \cmd{\@esphack} + (\cmd{\global})\cmd{\@ignoretrue}. + +It is not necessary to change any of the label or index macros to fit with +this code. + +\end{document} -- cgit v1.2.3