source: JEM-EUSO/esaf_lal/tags/v1_r0/esafdoc/DevelopersGuide/ROOT.tex @ 117

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\section{\ROOT{} integration}%\ref{ROOT UserGuide, Chap 13, Adding a Class}
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\ESAF{} is deeply connected with \ROOT{}. \ROOT{} classes are used to provide the user with a user friendly Graphical User Interface (GUI), an efficient I/O system and the automatic documentation generation.
Integration of new classes in ROOT is done with \code{ClassDef}, \code{ClassImp} macros and \code{rootcint} dictionary generator.
The \code{ClassDef} and \code{ClassImp} macros are necessary to link classes to the dictionary generated by CINT.

\code{rootcint} process class headers and parsing the class structure, builds the streamers needed for I/O. 
\path{LinkDef.hh} file in \code{include} directories tells rootcint for which classes to generate the method interface stubs.
.

In the class header files the following line must be added to class header files:

\begin{displaycode}
ClassDef(ClassName,ClassVersionID)
\end{displaycode}

The \code{ClassVersionID} is used by the \ROOT{} I/O system. This feature is basically reserved to the classes in \path{packages/common/root/} which are used to store data in the rootfile, like \code{EPhoton}, must have \code{ClassVersionID >= 1}.
Elsewhere standard ESAF classes do not need to be written on file therefore \code{ClassVersionID} must be equal to \code{0}.

\emph{NOTE}: The \code{ClassDef} macro must be the last item before the closing \verb+};+ in a class definition.  
It contains its own private and public tags so it can be added to either a private or public part of a class definition.

Similarly, in the source file must be added:

\begin{displaycode}
ClassImp(ClassName)
\end{displaycode}

which provides the interface needed to generate the documentation.

\code{ClassDef}, \code{ClassImp}, \ROOT{} I/O and RTTI systems are explained extensively in the \hbox{\ROOT{} User's Guide} \cite{bib:rootug}.
%LinkDef and RootCint
%The LinkDef.h file tells rootcint for which classes to generate the method interface stubs.