Use TeX macros to store multiple data

Question

I'm trying to use TeX macros to store multiple data such as website url/name. Here is an example :

\documentclass{article}

\def\Google{{http://www.google.com}{Google Search}}

\makeatletter
\newcommand*\WebSiteName[1]{\@WebSiteName\expandafter#1}
\newcommand*\WebSiteUrl[1]{\@WebSiteUrl\expandafter#1}
\newcommand*\@WebSiteName[2]{#2}
\newcommand*\@WebSiteUrl[2]{#1}
\makeatother

\begin{document}

  Name : \WebSiteName\Google \par
  Url  : \WebSiteUrl\Google

\end{document}

On this example, \WebSiteName\Google should write "Google Search" and \WebSiteUrl\Google should write "http://www.google.com".

But the problem is that \WebSiteName\Google writes http://www.google.comGoogle Search". I try to use \expandafter to combine two arguments in only one. Maybe that's the wrong method.

Answer 1

You're misplacing \expandafter: it must go before \@WebSiteName and \@WebSiteUrl. But it turns out that the two auxiliary macros are already in the LaTeX kernel:

\makeatletter
\newcommand{\WebSiteName}{\expandafter\@secondoftwo}
\newcommand{\WebSiteUrl}{\expandafter\@firstoftwo}
\makeatother

\newcommand{\NewSite}[3]{\newcommand#1{{#2}{#3}}}

\NewSite{\Google}{http://www.google.com}{Google Search}

When \WebSiteName\Google is found, it becomes

\expandafter\@secondoftwo\Google

and then \Google is expanded, giving

\@secondoftwo{http://www.google.com}{Google Search}

and, finally

Google Search

Answer 2

Thanks egreg.

Finally, after a little search, i used a different approch using the package datatool.

File: websites.csv

id,     url,                   name
Google, http://www.google.com, Google Search

File: document.tex

\documentclass{minimal}

\usepackage{datatool}

% set "," as separator between each entry
% "," is the default
% to use <tab> as separator, use \DTLsettabseparator
\DTLsetseparator{,}

% loads the database
\DTLloaddb{websites}{websites.csv}

\newcommand*\WebSiteName[1]{%
  \DTLgetvalueforkey{\temp}{name}{websites}{id}{#1}%
  \temp}

\newcommand*\WebSiteUrl[1]{%
  \DTLgetvalueforkey{\temp}{url}{websites}{id}{#1}%
  \temp}

\newcommand*\WebSite[1]{%
  \WebSiteName{#1}~\WebSiteUrl{#1}}

\begin{document}

  % show database
  \DTLdisplaydb{websites}

  \WebSiteName{Google}
  \WebSiteUrl{Google}
  \WebSite{Google}

\end{document}