[Tex/LaTex] LaTeX macro expander

expansionmacros

Is it possible to have LaTeX (or another program) to expand a the macros in a .tex file, and output the expanded LaTeX source?

If no such program exists: are LaTeX macros processed simply as string substitutions, before the document is interpreted? If so, it might be easy enough to write my own such converter.

Edit: The reason I ask is journals which don't accept LaTeX submissions with macros. It would be useful to be able to develop with my usual macros, and convert automatically to the 'macro-expanded' format for submission.

Best Answer

If you just want to see how LaTeX works, and what it does when macros are expanded, you can put \tracingmacros or \tracingall in your .tex file, and LaTeX will write the expansion process in the log file.

Related Solutions

[Tex/LaTex] Forcing macro expansion

\documentclass{article}
\makeatletter
\def\@FormatDateAuxA#1/#2/#3 #4.{%
    % Day
            \number#3\relax\space
    % Month
            \ifcase#2{}?#2?\or
            January\or February\or March\or April\or
            May\or June\or July\or August\or
            September\or October\or November\or December\else
            ?#2?\fi\space
    % Year
            \ifnum#1>99{}#1\else\ifnum#1>9{}19#1\else190#1\fi\fi}
\def\@FormatDateAuxB#1$#2.{{
    \typeout{\noexpand#1}
    \@FormatDateAuxA#1 X.}}
\def\FormatDate#1{\expandafter\@FormatDateAuxB#1$X.}
                  %%%%%%%%%%%%%
\makeatother
\begin{document}
\FormatDate{2015/4/15}
\def\Date{2015/4/15}
\FormatDate{\Date}
\end{document}

[Tex/LaTex] \expandafter to expand macro before macro call

The \expandafter command tries to expand one level the token immediately following the next one.

With your code, the tried token is {, which is not expandable.

Reaching the last token in the argument is impossible with \expandafter, because you don't know how many of them there are.

Some tricks are possible, though. The easiest one is to force complete expansion of the argument:

\documentclass{article}
\usepackage{graphicx}

\newcommand{\ext}{.jpg}

\newcommand\incPIC[1]{%
  \begingroup\edef\x{\endgroup
    \noexpand\includegraphics{#1}%
  }\x
}

\begin{document}

\incPIC{example-image\ext}

\end{document}

On the other hand, the \ext can better go in the definition:

\documentclass{article}
\usepackage{graphicx}

\newcommand{\ext}{.jpg}

\newcommand\incPIC[1]{%
  \begingroup\edef\x{\endgroup
    \noexpand\includegraphics{#1\ext}%
  }\x
}

\begin{document}

\incPIC{example-image}

\end{document}

A different trick with xparse and expl3, so it's easy to also accommodate the optional argument to \includegraphics.

\documentclass{article}
\usepackage{graphicx}
\usepackage{xparse}

\newcommand{\ext}{.jpg}

\ExplSyntaxOn
\cs_new_protected:Nn \gabriel_includegraphics:nnn
 {
  \includegraphics[#2]{#3#1}
 }
\cs_generate_variant:Nn \gabriel_includegraphics:nnn { V }

\NewDocumentCommand\incPIC {O{}m}
 {
  \gabriel_includegraphics:Vnn \ext { #1 } { #2 }
 }
\ExplSyntaxOff

\begin{document}

\incPIC{example-image}

\incPIC[width=3cm]{example-image}

\end{document}

See also Choosing whether to include PDF or PNG in PDFLaTeX for different strategies.

Best Answer

Related Solutions

[Tex/LaTex] Forcing macro expansion

[Tex/LaTex] \expandafter to expand macro before macro call

Related Question