"etc." abbreviation macro gives error when used in caption

Question

I've been using the abbreviation macros for i.e., e.g., and etc. that are provided in this post. However, I just discovered that the etc. macro, and a similar one I made for et al. both cause errors when used inside a caption. When I compile the code below, I get an error Argument of \@caption has an extra }. Is there a way to modify the macro to fix this? Thanks.

\documentclass{article}
\usepackage{caption}

\usepackage{xspace}
\newcommand*{\eg}{e.g.\@\xspace}
\newcommand*{\ie}{i.e.\@\xspace}

\makeatletter
\newcommand*{\etc}{%
    \@ifnextchar{.}%
        {etc}%
        {etc.\@\xspace}%
}
\makeatother

\begin{document}

\begin{figure}
\caption{Me \etc} % This causes problems
\label{}
\end{figure}

\end{document}

Answer 1

You should use \DeclareRobustCommand instead of \newcommand in order for the macro to work in headings and captions:

\documentclass{article}
\usepackage{caption}

\usepackage{xspace}
\DeclareRobustCommand{\eg}{e.g.\@\xspace}
\DeclareRobustCommand{\ie}{i.e.\@\xspace}

\makeatletter
\DeclareRobustCommand{\etc}{%
    \@ifnextchar{.}%
        {etc}%
        {etc.\@\xspace}%
}
\makeatother

\begin{document}
\begin{figure}
\caption{Me \etc \ie \eg} % Would cause problems if abbreviations were defined with \newcommand
\label{}
\end{figure}

\end{document}