How can I use an algorithm2e function macro inside an algorithm2e caption?

Question

Algorithm2e lets you define functions using \SetKwFunction{Fn}{Function} which you can then reference anywhere in the document (not just in an algorithm environment) using e.g. \Fn (which will output Function all nicely typeset in the right font). However, this doesn't work inside captions. For example, the following doc:

\documentclass{article}
\usepackage{algorithm2e}
\SetKwFunction{Fn}{Function}
\begin{document}
\begin{algorithm}
  \caption{\Fn, my function}
  \KwRet{0}\;
\end{algorithm}
\end{document}

dies with

Argument of \@caption has an extra }.
<inserted text> 
                \par 
l.6   \caption{\Fn, my function}

Anyone know what's going on, and how to fix it?

Answer 1

The macro has to be protected that it can be used inside caption:

\caption{\protect\Fn my function}

For more information why this is needed have a look at this question:

What is the difference between Fragile and Robust commands?