Combining subfloat and newfloat packages for sublistings environment

Question

I am using the subfloat package to group related figures; they show up like 1a, 1b, etc. in the List of Figures.

Now, I want to define a new listing float using the newfloat package, which generates its own List of Listings.

Alas, I am lacking something like a sublistings environment, which causes the listings to be labelled 1a, 1b, etc. as well:

\documentclass{article}
\usepackage[countmax]{subfloat}
\usepackage{newfloat}
\DeclareFloatingEnvironment{listing}

\begin{document}
\listoflistings

\begin{sublistings}
\begin{listing}
\caption{First listing}
\end{listing}
\begin{listing}
\caption{Second listing}
\end{listing}
\end{sublistings}

\end{document}

As far as I can see, the subfloat package has support for subfigures and subtables only.

I wasn't able to copy & modify its code to produce a sublistings environment that works with the float defined by newfloat. Can anyone help me out?

Answer 1

It's cargo cult programming, but it works: Take the possibly relevant code of subfloat.sty, enclose it into \makeatletter/\makeatother and replace every instance of figure with listing.

\documentclass{article}
\usepackage[countmax]{subfloat}
\usepackage{newfloat}
\DeclareFloatingEnvironment{listing}

\makeatletter
\newcommand*\thesubfloatlisting{\themainlisting\alph{subfloatlisting}}
\newenvironment{sublistings}{%
  \sublistingsbegin
}{%
  \sublistingsend
  \global\@ignoretrue
}
\let\c@subfloatlisting=\c@listing
\newif\ifinsubfloatlistings
\newcommand{\sublistingsbegin}{%
\ifinsubfloatlistings
  \PackageError{subfloat}{Cannot start subfloatlistings inside
    a\MessageBreak subfloatlisting area}{You probably have used
    \string\sublistingsbegin\space or \string\begin{sublistings} inside
      the^^Jsame environment or after \string\sublistingsbegin.}%
\fi
\global\insubfloatlistingstrue
  \refstepcounter{listing}%
  \protected@xdef\listing@value{\the\c@listing}%
  \protected@xdef\themainlisting{\thelisting}%
  \global\let\thelisting@original=\thelisting
  \setcounter{listing}{0}%
  \gdef\thelisting{\thesubfloatlisting}%
  \ifsubfloat@countmax
    {\def\@setref##1##2##3{%
      \ifx##1\relax
        \protect\G@refundefinedtrue
        \setcounter{subfloatlistingmax}{0}%
        \PackageWarningNoLine{subfloat}{Reference `##3' on page
          \thepage \space undefined\MessageBreak
          (count subfloatlistings)}%
      \else
        \setcounter{subfloatlistingmax}{\expandafter\@firstoftwo##1}%
      \fi}%
    \ref{subfloat@@listing\listing@value}}%
  \fi
%%  \@ifpackageloaded{sublisting}{%
    \let\p@sublisting=\thesubfloatlisting
%%  }{}%
  \ignorespaces
}
\newcommand{\sublistingsend}{%
\ifinsubfloatlistings
\else
  \PackageError{subfloat}{Cannot stop subfloatlistings outside
    a\MessageBreak subfloatlisting area}{You probably have used
    \string\sublistingsend\space or \string\end{sublistings} without
      starting a^^Jsubfloatlisting area using the same environment or
      \string\sublistingsbegin.}%
\fi
\global\insubfloatlistingsfalse
  \ifsubfloat@countmax
    \subfloat@listinglabel{subfloat@@listing\listing@value}%
  \fi
  \setcounter{listing}{\listing@value}%
  \global\let\thelisting=\thelisting@original
%%  \@ifpackageloaded{sublisting}{%
    \let\p@sublisting=\thelisting
%%  }{}%
  \ignorespaces
}
%%
\ifsubfloat@countmax
  \newcounter{subfloatlistingmax}
\else
  \PackageWarningNoLine{subfloat}{Numbers of floats not
    counted:\MessageBreak
    If you use one of the counters subfloatlistingmax or\MessageBreak
    subfloattablemax you will get strange error messages\MessageBreak
    containing \string\c@subfloatlistingmax\space or\MessageBreak
    \string\c@subfloattablemax:\MessageBreak
    Please switch on countmax or
    remove the code using\MessageBreak
    the counter then.}
\fi
\ifsubfloat@countmax
  \newcommand*\subfloat@listinglabel[1]{\@bsphack
    \protected@write\@auxout{}%
           {\string\newlabel{#1}{{\the\c@listing}{\thepage}}}%
    \@esphack}
\fi
\makeatother

\begin{document}
\listoflistings

\begin{sublistings}
\begin{listing}
\caption{First listing}
\end{listing}
\begin{listing}
\caption{Second listing}
\end{listing}
\end{sublistings}

\end{document}