Variations on the \expandafter TeX primitive

• E-mail: blflatex@gmail.com
• Released under the LaTeX Project Public License v1.3c or later See http://www.latex-project.org/lppl.txt

The package defines \multiexpand, \multiexpandafter, \MultiExpand and \MultiExpandAfter, replacing large chains of \expandafter. These four commands take as an argument the number of expansion to be done. If eTeX is available, this number is evaluated using \numexpr.

Say we want to expand \C five times before \A and \B in \A\B\C. The traditional approach would be to insert 31 \expandafter before \A and the same number before \B. With this package one can use any of

\expandafter\A\expandafter\B\romannumeral\multiexpand{5}\C

\expandafter\A\romannumeral\multiexpandafter{5}\B\C

\MultiExpandAfter{2}\A\MultiExpandAfter{5}\B\C

\MultiExpandAfter{2}\A\MultiExpandAfter{2}\B\MultiExpand{5}\C

In one step of expansion (triggered by the \expandafter's), \romannumeral\multiexpand{5} expands the following token 5 times, whereas \romannumeral\multiexpandafter{5} expands the token after that 5 times. The macros \MultiExpandAfter and \MultiExpand take two steps of expansion, but do not require \romannumeral. Another example is that in two steps of expansion,

\MultiExpandAfter{2}\a\MultiExpandAfter{3}{%
  \MultiExpandAfter{9}\b\MultiExpandAfter{10}\c\d}

expands \d 10 times, then \c 7 times (9-2), then \b once (3-2).

The package can be built from the file multiexpand.dtx' by running pdflatex multiexpand.dtx pdflatex multiexpand.dtx