Protecting the argument of a command from the effect of the command

Question

How can I "protect" an argument of a command from the effect of the command?

The link is interrupted by \spacedallcaps

\documentclass{scrreprt}

\usepackage[pdfspacing]{classicthesis}

\begin{document}

\spacedallcaps{\href{http://it.wikipedia.org/wiki/Pagina_principale}{test}}

\end{document}

Answer 1

If you want only test in spaced capital letters, obviously

\href{http://it.wikipedia.org/wiki/Pagina_principale}{\spacedallcaps{test}}

is the answer.

But if you want to make a chapter title into a link (classicthesis uses \spacedallcaps in that case, if I remember correctly), then you have to resort to a hack:

\documentclass{scrbook}
\usepackage[pdfspacing]{classicthesis}
\newcommand\mytemp{}

\begin{document}
\frontmatter
\tableofcontents
\mainmatter
\renewcommand\mytemp{http://it.wikipedia.org/wiki/Pagina_principale}
\chapter[test]{\href{\noexpand\mytemp}{test}}
\end{document}

The problem is not to show the link address to \MakeUppercase that would turn it in uppercase too.

However I don't recommend turning a chapter title into a link; better putting the link just at the start of the chapter text.