program.nw

\documentclass[a4paper,10pt,article,oneside,oldfontcommands]{memoir}
\let\subsubsection\subsection
\let\subsection\section
\let\section\chapter

\input{preamble.tex}
\noweboptions{longxref,breakcode}

\usepackage[noamsthm,notheorems]{beamerarticle}
\setjobnamebeamerversion{slides}

%\usepackage{authblk}
%\let\institute\affil

\title{%
  <title>
}
\author{%
  <author>
}
\affil{%
  <affil>
}

\begin{document}
\maketitle

\begin{abstract}
  \input{abstract.tex}
\end{abstract}
\clearpage

\tableofcontents
\clearpage

@
\section{Introduction}

This is the documentation of the [[<<<package>.py>>]] Python 3 script.
It does \dots

\subsection{Structural overview}

We use the standard structure for the script.
We have import statements at the top in the [[<<imports>>]] code block.
Then we have functions in the [[<<functions>>]] code block.
Finally, we have a [[main]] function which is run if the script is run directly 
but not if it is imported.
<<<package>.py>>=
#!/usr/bin/env python3

<<imports>>
<<functions>>

def main(argv):
    <<main body>>

if __name__ == '__main__':
  sys.exit(main(sys.argv[1:]))
@

Since we rely on the [[sys]] module we need
<<imports>>=
import sys
@

\subsection{Parsing command-line arguments}

The main body is
<<main body>>=
<<parse command-line arguments>>
<<process command-line arguments and do main execution>>
@

To parse command-line arguments we will make use of [[argparse]]:
<<imports>>=
import argparse
@

We first create a parser, then set up the valid arguments and finally provide 
the dictionary [[args]] containing each argument that was passed on the command 
line.
<<parse command-line arguments>>=
argp = argparse.ArgumentParser(description="<title>")

<<valid argparse arguments>>

args = vars(argp.parse_args(argv[1:]))
@

\subsection{Processing command-line arguments, the main functionality}

We expect a list of arguments on the command line.
<<valid argparse arguments>>=
argp.add_argument("arg", nargs="+", help="An argument to parse")
@



\printbibliography{}


\section{An index of the code blocks}
\nowebchunks

\end{document}