How do I define a \newcommand (or in LaTeX 3 a \NewDocumentCommand) which itself defines a \newcommand with arguments. For example in
\documentclass{article}
\begin{document}
\newcommand{\test}[1]
{
\newcommand{#1}[2]
{\#1 \#2}
}
\test{\you}
\you{3}{4}
\end{document}
I would like the output to be "3 4" not "#1 #2" as I want the #1 #2 to be interpreted in the internal \newcommand as arguments.
Something like this works. (It also works with xparse in the same way.)
\documentclass{article}
\newcommand{\test}[1]{%
\expandafter\newcommand\csname #1\endcsname[2]{%
##1 and ##2}}
\test{you}
\usepackage{xparse}
\NewDocumentCommand{\xtest} {m}
{%
\expandafter\NewDocumentCommand\csname #1\endcsname {mm}
{##1 and also ##2}%
}
\xtest{andher}
\begin{document}
\you{3}{4}
\test{me}
\me{5}{6}
\andher{7}{8}
\xtest{andhim}
\andhim{9}{10}
\end{document}
# again (####1).
##1) in an argument?, Nesting command definitions more than two levels and Why do parameters of \renewcommand need to double up the # within a \foreach.
The LaTeX2e kernel defined \@namedef{<csname>} that could be used exactly for this purpose, as it is defined as:
\def\@namedef#1{\expandafter\def\csname #1\endcsname}
It sets up the definition of its argument as a control sequence, awaiting the actual replacement text as part of the usual \def construction.
\documentclass{article}
\makeatletter
\newcommand{\test}[1]{\@namedef{#1}##1##2{##1 and ##2}}
\makeatother
\begin{document}
\test{you}\you{3}{4}
\end{document}
\namedef{<csname>} expands to \expandafter\def\csname <csname>\endcsname, which expands to \def\<csname>.
