User:Timothee Flutre/Notebook/Postdoc/2012/05/16

Typical templates for Python scripts, C++ programs and others

It is always rewarding on the long term to start any piece of computer software with a minimum amount of generic code (verbose, command-line options, help message, license, etc). But it's a pain to write all this every time, right? So below are my typical templates for any Python script, C++ program, Beamer presentation, Bash script, etc.

• Easy user documentation: I'm a firm believer that it is necessary to add some user documentation, even minimal, to any program. An easy way to do this is to simply generate such documentation from the "help" message, as long as it is "properly" formatted (see help2man). The following commands work for any programming language:

help2man -o myprogram.man ./myprogram
man ./myprogram.man
groff -mandoc myprogram.man > myprogram.ps
ps2pdf myprogram.ps myprogram.pdf

• Python: it is assumed that the code below is copied into a file named "MyClass.py".

#!/usr/bin/env python

# Author: Timothee Flutre
# License: GPL-3
# Aim: does this and that

import sys
import os
import getopt
import time
import datetime
import math


class MyClass(object):
    
    def __init__(self):
        self.verbose = 1
        self.input = ""
        
        
    def help(self):
        msg = "`%s' does this and that.\n" % os.path.basename(sys.argv[0])
        msg += "\n"
        msg += "Usage: %s [OPTIONS] ...\n" % os.path.basename(sys.argv[0])
        msg += "\n"
        msg += "Options:\n"
        msg += " -h, --help\tdisplay the help and exit\n"
        msg += " -V, --version\toutput version information and exit\n"
        msg += " -v, --verbose\tverbosity level (0/default=1/2/3)\n"
        msg += " -i\tinput"
        msg += "\n"
        msg += "Examples:\n"
        print msg; sys.stdout.flush()
        
        
    def version(self):
        msg = "%s 0.1\n" % os.path.basename(sys.argv[0])
        msg += "\n"
        msg += "License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>\n"
        msg += "This is free software; see the source for copying conditions.  There is NO\n"
        msg += "warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n"
        print msg; sys.stdout.flush()
        
        
    def setAttributesFromCmdLine(self):
        try:
            opts, args = getopt.getopt( sys.argv[1:], "hVv:i:",
                                        ["help", "version", "verbose="])
        except getopt.GetoptError, err:
            sys.stderr.write("%s\n" % str(err))
            self.help()
            sys.exit(2)
        for o, a in opts:
            if o == "-h" or o == "--help":
                self.help()
                sys.exit(0)
            elif o == "-V" or o == "--version":
                self.version()
                sys.exit(0)
            elif o == "-v" or o == "--verbose":
                self.verbose = int(a)
            elif o == "-i":
                 self.input = a
            else:
                assert False, "unhandled option"
                
                
    def checkAttributes(self):
        if self.input == "":
            msg = "ERROR: missing compulsory option -i"
            sys.stderr.write("%s\n\n" % msg)
            self.help()
            sys.exit(1)
        if not os.path.exists(self.input):
            msg = "ERROR: can't find '%s'" % self.input
            sys.stderr.write("%s\n\n" % msg)
            self.help()
            sys.exit(1)
            
            
    def run(self):
        self.checkAttributes()
        
        if self.verbose > 0:
            msg = "START %s" % time.strftime("%Y-%m-%d %H:%M:%S")
            startTime = time.time()
            print msg; sys.stdout.flush()
            
        # ... specific code ...
        
        if self.verbose > 0:
            msg = "END %s" % time.strftime("%Y-%m-%d %H:%M:%S")
            endTime = time.time()
            runLength = datetime.timedelta(seconds=
                                           math.floor(endTime - startTime))
            msg += " (%s)" % str(runLength)
            print msg; sys.stdout.flush()
            
            
if __name__ == "__main__":
    i = MyClass()
    i.setAttributesFromCmdLine()
    i.run()

• C++: it is assumed that the code below is copied into a file named "myprogram.cpp" and that the file "utils.cpp" is present in the same directory, along with the corresponding header utils.h.

/** \file myprogram.cpp
 *
 *  `myprogram' does this and that.
 *  Copyright (C) 2011,2012 Timothee Flutre
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *  g++ -Wall -g utils.cpp myprogram.cpp -lgsl -lgslcblas -lz -o myprogram
*/

#include <cmath>
#include <ctime>
#include <getopt.h>

#include <iostream>
#include <string>
using namespace std;

#include "utils.h"

/** \brief Display the help on stdout.
*/
void help (char ** argv)
{
  cout << "`" << argv[0] << "'"
       << " does this and that." << endl
       << endl
       << "Usage: " << argv[0] << " [OPTIONS] ..." << endl
       << endl
       << "Options:" << endl
       << "  -h, --help\tdisplay the help and exit" << endl
       << "  -V, --version\toutput version information and exit" << endl
       << "  -v, --verbose\tverbosity level (0/default=1/2/3)" << endl
       << "  -i, --in\tinput" << endl
       << endl
       << "Examples:" << endl
       << "  " << argv[0] << " -i <input>" << endl
       << endl
       << "Remarks:" << endl
       << "  This is my typical template file for C++." << endl
    ;
}

/** \brief Display version and license information on stdout.
 */
void version (char ** argv)
{
  cout << argv[0] << " " << __DATE__ << " " << __TIME__ << endl
       << endl
       << "Copyright (C) 2011,2012 T. Flutre." << endl
       << "License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>" << endl
       << "This is free software; see the source for copying conditions.  There is NO" << endl
       << "warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE." << endl
       << endl
       << "Written by T. Flutre." << endl;
}

/** \brief Parse the command-line arguments and check the values of the 
 *  compulsory ones.
 */
void
parseArgs (
  int argc,
  char ** argv,
  string & input,
  int & verbose)
{
  int c = 0;
  while (true)
  {
    static struct option long_options[] =
      {
        {"help", no_argument, 0, 'h'},
        {"version", no_argument, 0, 'V'},
        {"verbose", required_argument, 0, 'v'},
        {"input", required_argument, 0, 'i'},
        {0, 0, 0, 0}
      };
    int option_index = 0;
    c = getopt_long (argc, argv, "hVv:i:",
                     long_options, &option_index);
    if (c == -1)
      break;
    switch (c)
    {
    case 0:
      if (long_options[option_index].flag != 0)
        break;
    case 'h':
      help (argv);
      exit (0);
    case 'V':
      version (argv);
      exit (0);
    case 'v':
      verbose = atoi(optarg);
      break;
    case 'i':
      input = optarg;
      break;
    case '?':
      printf ("\n"); help (argv);
      abort ();
    default:
      printf ("\n"); help (argv);
      abort ();
    }
  }
  if (input.empty())
  {
    printCmdLine (argc, argv);
    fprintf (stderr, "ERROR: missing compulsory option -i\n\n");
    help (argv);
    exit (1);
  }
  if (! doesFileExist (input))
  {
    printCmdLine (argc, argv);
    fprintf (stderr, "ERROR: can't find '%s'\n\n", input.c_str());
    help (argv);
    exit (1);
  }
}

int main (int argc, char ** argv)
{
  string input;
  int verbose = 1;
  
  parseArgs (argc, argv, input, verbose);
  
  time_t startRawTime, endRawTime;
  if (verbose > 0)
  {
    time (&startRawTime);
    cout << "START " << argv[0] << " (" << time2string (startRawTime) << ")"
         << endl
         << "compiled -> " << __DATE__ << " " << __TIME__
         << endl << flush;
    printCmdLine (argc, argv);
  }
  
  // ... specific code ...
  
  if (verbose > 0)
  {
    time (&endRawTime);
    cout << "END " << argv[0] << " (" << time2string (endRawTime) << ")"
         << endl
         << "elapsed -> " << elapsedTime(startRawTime, endRawTime)
         << endl
         << "max.mem -> " << getMaxMemUsedByProcess () << " kB"
         << endl;
  }
  
  return EXIT_SUCCESS;
}

• Bash: sometimes it's easier to write a script in bash rather than in python. This is especially the case when one wants to use pipes, eg. zcat data.txt.gz | awk '{print $1}', or when one wants to use a glob to pass multiple files to the script, eg. ./myscript.bash -i "input*.txt".

#!/usr/bin/env bash

# Author: Timothee Flutre
# License: GPL-3
# Aim: does this and that

function help () {
    msg="\`$0' does this and that.\n"
    msg+="\n"
    msg+="Usage: $0 [OPTIONS] ...\n"
    msg+="\n"
    msg+="Options:\n"
    msg+="  -h, --help\tdisplay the help and exit\n"
    msg+="  -V, --version\toutput version information and exit\n"
    msg+="  -v, --verbose\tverbosity level (0/default=1/2/3)\n"
    msg+="  -i, --in\tinput\n"
    msg+="\n"
    msg+="Examples:\n"
    msg+="  $0 -i <input>\n"
    echo -e "$msg"
}

function version () {
    msg="$0 0.1\n"
    msg+="\n"
    msg+="Copyright (C) 2012 T. Flutre.\n"
    msg+="License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>\n"
    msg+="This is free software; see the source for copying conditions.  There is NO\n"
    msg+="warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n"
    msg+="\n"
    msg+="Written by T. Flutre.\n"
    echo -e "$msg"
}

# source http://www.linuxjournal.com/content/use-date-command-measure-elapsed-time
function timer () {
    if [[ $# -eq 0 ]]; then
        echo $(date '+%s')
    else
        local  stime=$1
        etime=$(date '+%s')
        if [[ -z "$stime" ]]; then stime=$etime; fi
        dt=$((etime - stime))
        ds=$((dt % 60))
        dm=$(((dt / 60) % 60))
        dh=$((dt / 3600))
        printf '%d:%02d:%02d' $dh $dm $ds
    fi
}

function parseArgs () {
    TEMP=`getopt -o hVv:p:f:c:g:o:i: -l help,version,verbose: \
        -n "$0" -- "$@"`
    if [ $? != 0 ] ; then echo "ERROR: getopt failed" >&2 ; exit 1 ; fi
    eval set -- "$TEMP"
    while true; do
        case "$1" in
            -h|--help) help; exit 0; shift;;
            -V|--version) version; exit 0; shift;;
            -v|--verbose) verbose=$2; shift 2;;
            -i|--in) input=$2; shift 2;;
            --) shift; break;;
            *) echo "ERROR: options parsing failed"; exit 1;;
        esac
    done
    if [ "x${input}" == "x" ]; then
        echo "ERROR: missing compulsory option -i"; echo; help; exit 1
    fi
    if [ ! -f ${input} ]; then
        echo "ERROR: can't find '${input}'"; exit 1
    fi
}

verbose=1
input=""
parseArgs "$@"

if [ $verbose -gt "0" ]; then
    printf "START %s %s\n" $(date +"%Y-%m-%d") $(date +"%H:%M:%S")
    startTime=$(timer)
fi

# ... specific code ...
sleep 1

if [ $verbose -gt "0" ]; then
    printf "END %s %s" $(date +"%Y-%m-%d") $(date +"%H:%M:%S")
    printf " (%s)\n" $(timer startTime)
fi

• Latex-Beamer: it is assumed that the code below is copied into a file named "mypresentation.tex" and that several packages are already installed. The current directory is also assumed to contain a sub-directory named "figures" in which are saved all picture files included in the presentation.

% Author: Timothée Flutre

\documentclass{beamer}
\usepackage{amsmath}
\usepackage{bm} % to have mathematical symbols in bold
\usepackage{hyperref}
\hypersetup{colorlinks, linkcolor=black, urlcolor=gray}
\usepackage{multirow}
\usepackage{tikz}
\usepackage[francais]{babel}
\usepackage[utf8]{inputenc}

\graphicspath{{./figures/}}

%-----------------------------------------------------------------------------

\setbeamertemplate{caption}[numbered]
\setbeamerfont{caption}{size=\scriptsize}
\setbeamertemplate{navigation symbols}{}
\setbeamercolor{alerted text}{fg=purple}

\setbeamertemplate{footline}
{
  \leavevmode
  \hbox{
    \hspace*{-0.06cm}
    \begin{beamercolorbox}[wd=.2\paperwidth,ht=2.25ex,dp=1ex,center]{author in head/foot}
      \usebeamerfont{author in head/foot}\insertshortauthor \hspace*{1em} \insertshortinstitute
    \end{beamercolorbox}
    \begin{beamercolorbox}[wd=.50\paperwidth,ht=2.25ex,dp=1ex,center]{section in head/foot}
      \usebeamerfont{section in head/foot}\insertshorttitle
    \end{beamercolorbox}
    \begin{beamercolorbox}[wd=.27\paperwidth,ht=2.25ex,dp=1ex,right]{section in head/foot}%
      \usebeamerfont{section in head/foot}\insertshortdate{}\hspace*{2em}
      \insertframenumber{} / \inserttotalframenumber\hspace*{2ex}
    \end{beamercolorbox}
  }
  \vskip0pt
}

\AtBeginSection[]
{
  \begin{frame}
    \frametitle{Outline}
    \addtocounter{framenumber}{-1}
    \tableofcontents[currentsection]
  \end{frame}
}

%-----------------------------------------------------------------------------

\title[Short title]{Long title}
\author[T. Flutre]{Timoth\'{e}e Flutre}
\institute[Short affiliation]{Long affiliation}
\date{\today}

begin{document}

\begin{frame}
\titlepage
\end{frame}                                                                                                                       

\begin{frame}
\frametitle{Outline}
\tableofcontents
\end{frame}

\section{First section}
\begin{frame}
\frametitle{I.1.}
\begin{itemize}
\item 
\end{itemize}
\end{frame}

\section{Second section}

\begin{frame}
\frametitle{II.1.}
\begin{center}
%\includegraphics[width=0.95\textwidth,height=0.90\textheight,keepaspectratio=true]{myplot}%
\end{center}
\end{frame}

end{document}