bug in listings package?

Question

It seems as if the listings package can not be loaded after all other packages using \AtBeginDocument

\documentclass[]{scrbook} % 
\AtBeginDocument{\RequirePackage{listings}}
\begin{document}
\end{document}

This raises the error

! Undefined control sequence.

<argument> ... \iffalse }{}\lst@ifnumberbychapter

In the code sequence

\AtBeginDocument{
  \@ifundefined{thechapter}{\let\lst@ifnumberbychapter\iffalse}{}
  \lst@ifnumberbychapter
      \newcounter{lstlisting}[chapter]
      \gdef\thelstlisting%
           {\ifnum \c@chapter>\z@ \thechapter.\fi \@arabic\c@lstlisting}
  \else
      \newcounter{lstlisting}
      \gdef\thelstlisting{\@arabic\c@lstlisting}
  \fi}

Is this a bug or am I misusing \AtBeginDocument ?

Answer 1

You probably are misusing \AtBeginDocument :-)

I had no idea packages can be loaded then; but it seems they can be. listings, however, uses \AtBeginDocument itself. I'd say that's why your code doesn't work.

Actually, I have checked: yes, listings \lets \lst@ifnumberbychapter in \AtBeginDocument.