# Beamer bug? Description with item width and overlay in beamerarticle

This MWE is really minimal. We make use of the {description} environment which in beamer takes two optional arguments: overlay specification, and item width.

\documentclass{beamer}
%\documentclass{article}
%\usepackage{beamerarticle}
\begin{document}
\begin{frame}{The Animal Kingdom}
\begin{description}[<+->][Guans of America]
\item[Gnus] these are large cow-like animals
\item[Gnats] much smaller than gnus
\item[Guans of America] mid sized, I think
\end{description}
\end{frame}
\end{document}


Now, this works great in beamer mode, but not in beamerarticle, which generates the following message:

! LaTeX Error: Something's wrong--perhaps a missing \item.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
...

l.7         \item[Gnus] t
hese are large cow-like animals
?


This seems like a bug, IMHO. I wonder if there is a workaround that scales. I have few dozens instances of this problem in a large presentation.

Joseph Wright's fix to this bug in the beamer source can be found here.

 {
\AtBeginDocument{
\let\beamer@origdescription=\description
-    \renewcommand{\description}[1][]{\beamer@origdescription}
+    % The description environment doesn't use either optional
+    % arg in article mode, so simply gobble them
+    \def\description{%
+      \@ifnextchar[%]
+        {\beamer@description@}
+        {\beamer@origdescription}%
+    }
+    \def\beamer@description@[#1]{%
+      \@ifnextchar[%]
+        {\beamer@description@@}
+        {\beamer@origdescription}%
+    }
+    \def\beamer@description@@[#1]{\beamer@origdescription}
}
}


I tried using this idea in an \mode<article> guard, but could not. Any help in finding a temporary work around until the release of the next version, would be greatly appreciated.

Here is a simple workaround: move the overlay specification to the frame environment. In the MWE example, write:

\documentclass{beamer}
%\documentclass{article}
%\usepackage{beamerarticle}
\begin{document}
\begin{frame}[<+->]{The Animal Kingdom}
\begin{description}[Guans of America]
\item[Gnus] these are large cow-like animals
\item[Gnats] much smaller than gnus
\item[Guans of America] mid sized, I think
\end{description}
\end{frame}
\end{document}


In frames with richer overlay specification, you would have to work around the default overlay specification.