My titleclass breaks subsubsection headings

Question

I am using the titlesec package in conjunction with the ACM SIG Alternate document class to create a special kind of subsubsection as follows:

\documentclass{sig-alt-full}

% +++++ Begin Experiment Subsection ++++++
\newcommand{\subparagraph}{} % not defined in cls template
\usepackage{titlesec}
\titleclass{\experiment}{straight}[\subsection]
\newcounter{experiment}
\renewcommand{\theexperiment}{(\roman{experiment})}
\titleformat{\experiment}[hang]{\normalfont\normalsize\bfseries}
        {Experiment\,(\roman{experiment}):}{.5em}{}[]
\titlespacing{\experiment}{0pt}{*2.5}{.5em}
% +++++ End Experiment Subsection ++++++

\begin{document}
\section{Section}
\subsection{Subsection}
\subsubsection{Subsubsection}
\subsection{Experiments}
\experiment{Not a Subsubsection}
\end{document}

The problem is that elsewhere in my document I want to use plain old subsubsections. However, with the definition of my new titleclass, the formatting of the plain old subsubsection heading looks different than before and the numbering is also gone from the heading.

How can I get my \experiment subsubsections while leaving the regular subsubsections untouched?

Answer 1

The easiest way is to forget about titlesec that's not compatible with the used class and to define \experiment in terms of \subsubsection:

\documentclass{sig-alt-full}

\usepackage{hyperref,bookmark}

%%% To cope with the "non standard" way the class uses
\newfont{\experimentfnt}{ptmb8t at 11pt}

\newcounter{experiment}
\renewcommand{\theexperiment}{(\roman{experiment})}
\newcommand{\experimentname}{Experiment}

\newcommand{\experiment}[1]{%
  \subsubsection*{\refstepcounter{experiment}%
    \experimentfnt Experiment~\theexperiment: #1}%
}

\begin{document}
\section{Section}\label{s}
\subsection{Subsection}
\subsubsection{Subsubsection}

\subsection{Experiments}
\experiment{Not a Subsubsection\label{ex1}}

In this experiment we do something; it is \autoref{ex1}.

\end{document}

The only drawback is that the label must be specified inside the argument. However, it seems that the class has many problems with hyperref, but not only: the labels are wrongly written in the .aux file, because \thepage is made equivalent to \relax.

I strongly suggest not using this class.