%%%%%%%%%1%%%%%%%%%2%%%%%%%%%3%%%%%%%%%4%%%%%%%%%5 % Bundled source file for the IFMTARG package %--------1---------2---------3---------4---------5 % Please see the accompanying README for author, % license, documentation and installation information %%%%%%%%%1%%%%%%%%%2%%%%%%%%%3%%%%%%%%%4%%%%%%%%%5 \RequirePackage{filecontents} \begin{filecontents*}{ifmtarg.sty} \NeedsTeXFormat{LaTeX2e} \ProvidesPackage{ifmtarg}[2018/04/16 v1.2b check for an empty argument] \begingroup \catcode`\Q=3 \long\gdef\@ifmtarg#1{\@xifmtarg#1QQ\@secondoftwo\@firstoftwo\@nil} \long\gdef\@xifmtarg#1#2Q#3#4#5\@nil{#4} \long\gdef\@ifnotmtarg#1{\@xifmtarg#1QQ\@firstofone\@gobble\@nil} \endgroup \endinput \end{filecontents*} %%%%%%%%%1%%%%%%%%%2%%%%%%%%%3%%%%%%%%%4%%%%%%%%%5 % Conditionally compile the documentation & generate the .ins file: \providecommand\documentationCompile{Y} \makeatletter \if\documentationCompile N \expandafter\@@end \fi \begin{filecontents*}{ifmtarg.ins} %&latex \def\documentationCompile{N} \input ifmtarg.tex \csname@@end\endcsname \end{filecontents*} \makeatletter \documentclass[twocolumn]{ltxdoc} \usepackage{shortvrb} \MakeShortVerb\| \usepackage[it,medium]{titlesec} \usepackage{array,ifmtarg,bigfoot,fancyvrb} \usepackage[svgnames]{xcolor} \usepackage[colorlinks,linktocpage]{hyperref} \usepackage{geometry} \geometry{margin=2cm} \usepackage{tocloft,varwidth} \setcounter{tocdepth}{1} \def\tocwidthA{0.55} \def\tocwidthB{0.44} \def\cftpartfont{\scshape} \def\cftsecfont{\small} \cftbeforesecskip=0pt \def\cftpartleader{} \def\cftpartafterpnum{\cftparfillskip} \def\cftsecleader{} \def\cftsecafterpnum{\cftparfillskip} \DeclareRobustCommand\pkg{\textsf} \def\pkgopt#1{\texttt{[#1]}} \newcommand\chng[1]{\marginpar{\footnotesize\raggedright\textsf{#1}}} \def\PDF{\textsc{pdf}} \def\PS{\textsc{ps}} \def\DVI{\textsc{dvi}} \def\EPS{\textsc{eps}} \usepackage{amsmath,listings} \lstset{basicstyle=\ttfamily,columns=fullflexible} \usepackage{changepage} \usepackage[T1]{fontenc} \usepackage{microtype} \usepackage{lmodern} \usepackage[sc,osf]{mathpazo} \linespread{1.1} \frenchspacing \GetFileInfo{ifmtarg.sty} \begin{document} {\addtocontents{toc}{\protect\begin{varwidth}[t]{\tocwidthA\linewidth}}} \title{The \pkg{ifmtarg} package} \author{% Author: Donald Arseneau, and Peter Wilson, Herries Press\\ Maintainer: Will Robertson\\ \texttt{will dot robertson at latex-project dot org}% } \date{\fileversion \qquad \filedate} \maketitle \section{Documentation} The \pkg{ifmtarg} package provides an if--then--else programmer's command \verb|\@ifmtarg| for testing for an empty macro argument. `Empty' here refers to an argument of zero or more spaces only.\footnote{If you need a command to test for emptiness that doesn't include spaces, use the \verb|\tl_if_empty:nTF| conditional from the \pkg{expl3} package. \verb|\@ifmtarg| is equivalent to \pkg{expl3}'s \verb|\tl_if_blank:nTF|.} The command is fully expandable; its syntax is: \begin{quote} \cmd{\@ifmtarg}\marg{arg}\marg{Code for arg empty} \\\null\hfill \marg{Code for arg not empty} \end{quote} A variation is provided, \cmd{\@ifnotmtarg}, to be used when only the `false' branch is required. It is slightly more efficient when code is only required for a non-empty argument. \begin{quote} \cmd{\@ifnotmtarg}\marg{arg}\marg{Code for not empty} \end{quote} \section{Examples} \begin{verbatim} \newcommand\isempty[1]{\@ifmtarg{#1}{YES}{NO}} \end{verbatim} \nobreak \begin{tabular}{@{\hspace{1.8em}}>{\color{SeaGreen}}l@{$\quad\to\quad$}>{\ttfamily}l@{}} \verb+\isempty{}+ & YES \\ \verb+\isempty{ }+ & YES \\ \verb+\isempty{E}+ & NO \\ \verb+\isempty{ E }+ & NO \end{tabular} \begin{verbatim} \newcommand\isnotempty[1]{\@ifnotmtarg{#1}{YES}} \end{verbatim} \nobreak \begin{tabular}{@{\hspace{1.8em}}>{\color{SeaGreen}}l@{$\quad\to\quad$}>{\ttfamily}l@{}} \verb+\isnotempty{}+ & \\ \verb+\isnotempty{ }+ & \\ \verb+\isnotempty{E}+ & YES \\ \verb+\isnotempty{ E }+ & YES \end{tabular} \newpage \section{History} (\emph{Peter's comments follow.}) In an Email to me on 13 March 2000, Donald Arseneau pointed out some failings with my original definition of the \cmd{\@ifmtarg} command: % \begin{verbatim} \newcommand{\@ifmtarg}[3]{% \edef\@mtarg{\zap@space#1 \@empty}% \ifx\@empty\@mtarg\relax #2\else #3\fi} \end{verbatim} % It works most of the time correctly but Donald showed that it can give unexpected results under conditions that I had not thought of. He suggested the coding that now appears in the package above for the \cmd{\@ifmtarg} and \cmd{\@ifnotmtarg} commands. For a discussion on detecting empty arguments see \href{http://www.ctan.org/pub/tex-archive/info/aro-bend/answer.002}{\texttt{CTAN/info/aro-bend/answer.002}} \section*{Change History} \begin{itemize} \item[v1.2a] New maintainer (Will Robertson) \item[v1.2b] Typo in documentation example code \end{itemize} \section*{Licence and copyright} This work may be modified and/or distributed under the terms and conditions of the \LaTeX\ Project Public License\footnote{\url{http://www.latex-project.org/lppl.txt}}, version~1.3c or later (your choice). The current maintainer of this work is Will Robertson. \bigskip \noindent Copyright Peter Wilson, 1996 \\ Copyright Peter Wilson and Donald Arseneau, 2000 {\addtocontents{toc}{\protect\end{varwidth}\protect\hfill}} {\addtocontents{toc}{\protect\begin{varwidth}[t]{\protect\tocwidthB\protect\linewidth}}} \clearpage \parindent=0pt \section{Implementation} \VerbatimInput{ifmtarg.sty} {\addtocontents{toc}{\protect\end{varwidth}}} \end{document}