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When I compile this minimum LaTeX file:
\documentclass{report}
\def\defMacro#1#2{\expandafter\def\csname#1\endcsname{#2}}
\def\useMacro#1{\csname#1\endcsname}
\usepackage{pgffor}
\begin{document}
\foreach \n in {0,1,...,10}{
\defMacro{number:\n}{\n}
}
\useMacro{number:8}
\end{document}
I obtain no PDF output. What do I mistake?
The \foreach loop content is executed in a group for each iteration, therefore the definition is only local. You would need to add \global in front of \defMacro.
The reason the \useMacro is not causing an error is because \csname has the side effect that the resulting macro is defined equal to \relax if is was undefined before.
\defMacro definitions global, which might be an issue dependent on the use. For your own private macros this shouldn't be an issue, but I wouldn't do that for package code.
Apr 20, 2011 at 15:36
etoolboxpackage provides\csdefand\csusewhich do the same as\defMacroand\useMacro. LaTeX itself defines\@namedefand\@nameuse. The\csusemacro takes care not to define the given macro (equal to\relax) if it doesn't exists. It expands to nothing in this case.