\chapter{Coding Style Guidelines}
\label{guidelines}

An important characteristic of source code is that it is written only
once but usually it is read many times (e.g. when debugging things,
adding features, etc.). For this reason, good programming frameworks
always aim to be as readable as possible, even if comes with higher
effort to write them in the first place. The remainder of this section
is very similar to the \Dune coding guidelines found at the \Dune
website~\cite{DUNE-HP}. These guidelines are also strongly recommended
for working with \eWoms. Some of these coding style rules may seem
like splitting hairs to you, but they do make it much easier for
everybody to work on code that has not been written by oneself.

\begin{itemize}
\item Naming: 
\begin{itemize}
\item Comments: They are helpful! Use comments extensively to explain
  what your code does, but please refrain from adding trivial
  comments. Trivial comments are, for example comments that only
  parrot the source code (``this method sets a'' as the comment for a
  method called \texttt{setA()}), or comments that explain language
  features (``if b is true then a is c else d'' for the statement
  \texttt{a = b?c:d}).
\item All comments, documentation and variable or type names are
  exclusivly using the English language.
\item Variables: Names for variables should only feature letters and
  digits. The first letter should be lower case. If your variable
  names consists of several words, then the first letter of each new
  word should be capitalized.
\item Variables and methods should be named as self-explanatory as
  possible. Especially, this means abbreviations should be avoided
  (for example, use 'saturation' in stead of 'S')
\item Method parameters which are not self-explanatory should always
  have a meaningful comment a at calling sites. Example:
\begin{lstlisting}[style=eWomsCode]
   localResidual.eval(/*includeBoundaries=*/true);
\end{lstlisting}
\item Private attributes: Names of private attributes should end with
  an underscore and are supposed to be the only variables that contain
  underscores.
\item Typenames: For typenames (classes, structures, typedefs, etc),
  the same rules as for variables apply. The only difference is that
  the first letter should be a capital one.
\item Macros: The use of preprocessor macros is strongly
  discouraged. If you have to use them for whatever reason, please use
  capital letters only.
\item Guardian macros: Every header file traditionally begins with the
  definition of a preprocessor macro that is used to make sure that
  the header file is only included once. If your header file is
  called 'myheaderfile.hh', this constant should be named
  \texttt{DUMUX\_MYHEADERFILE\_HH}.
\item Files: File names should exclusively consist of lower case
  letters. Header files get the suffix .hh, implementation files the
  suffix .cc
\end{itemize}

\item Documentation: \eWoms, as any software project of similar
  complexity, will stand and fall with the quality of its
  documentation.  Therefore, it is of paramount importance that you
  document everything you do well! We use the doxygen system to
  extract easily-readable documentation from the source code. Please
  use its syntax everywhere. In particular, please comment
  \textbf{all}
\begin{itemize}
\item Method parameters
\item Template parameters
\item Return values 
\item Exceptions thrown by a method
 \end{itemize}
 Since we all know that writing documentation is not well-liked and is
 frequently defered to some vague 'next week', we herewith proclaim
 the Doc-Me Dogma . It goes like this: Whatever you do, and in
 whatever hurry you happen to be, please document everything at least
 with a {\verb /** $\backslash$todo Please doc me! */}. That way at
 least the absence of documentation is documented, and it is easier to
 get rid of it systematically.
\item Exceptions: The use of exceptions for error handling is
  encouraged. Until further notice, all exceptions thrown are derived
  from \texttt{Dune::Exception}.
\item Debugging code: Code which is only there to ease the debugging
  process should always be switched off if the preprocessor macro
  NDEBUG is defined. In particular, all assertations are automatically
  removed. Use those assertations freely!
\end{itemize}

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