Autotools are a great way of packaging binary applications in Linux.The autotools need to be installed by installing the auto-tools-dev and other dependencies.It uses the old Makefile way for compiling the program and checking dependencies. Here in this we take a sample C program depending on wxWidgets and openGL and build the install scripts using Autotools.Note that the directory structure is as follows :
|___Canvas
           |____src [ the source folder ]
           |         |__paint.cpp
           |____res [ the resources and data ]

Autotools uses a predefined directory for installing files and these directories are named in the autotools site.For eg. $PREFIX stands for /usr/local/ hence when you write your program make sure to use these locations.

Autoscan: We use an automated tool to generate the initial configure.scan script. In the root directory run 'autoscan' command.This will generate a configure.scan and a report there by traversing through all the directories for dependencies. Now rename this to 'configure.ac' and edit it as follows.

#                                               -*- Autoconf -*-
# Process this file with autoconf to produce a configure script.

AC_PREREQ([2.69])
AC_INIT([canvas], [1.0], [saswat.cs11@iitp.ac.in])
AM_INIT_AUTOMAKE([-Wall foreign])
AC_CONFIG_SRCDIR([src/paint.cpp])
AC_CONFIG_HEADERS([config.h])

# Checks for programs.
AC_PROG_CXX

# Checks for libraries.
AM_OPTIONS_WXCONFIG
reqwx=2.4.0
AM_PATH_WXCONFIG($reqwx, wxWin=1)
if test "$wxWin" != 1; then
 AC_MSG_ERROR([
  wxWidgets must be installed on your system.
 
  Please check that wx-config is in path, the directory
  where wxWidgets libraries are installed (returned by
  'wx-config --libs' or 'wx-config --static --libs' command)
  is in LD_LIBRARY_PATH or equivalent variable and
  wxWidgets version is $reqwx or above.
  ])
fi
 
CPPFLAGS="$CPPFLAGS $WX_CPPFLAGS"
CXXFLAGS="$CXXFLAGS $WX_CXXFLAGS_ONLY"
CFLAGS="$CFLAGS $WX_CFLAGS_ONLY"
LIBS="$LIBS $WX_LIBS -lGL -lGLU -lglut `wx-config --gl-libs`"

# Checks for header files.

# Checks for typedefs, structures, and compiler characteristics.
AC_CHECK_HEADER_STDBOOL

# Checks for library functions.
AC_FUNC_MALLOC


AC_OUTPUT(Makefile src/Makefile res/Makefile)

Now notice the Macros in the section.AC_INIT initialize the package name and version and bug to send mail.AC_PROG_CXX checks for C++ in the system.We then check for wxWidgets in the system.This is present in their wiki for code above.Next add the FLAGS for compilation of librariesAC_OUTPUT checks for the Makefiles that should be generated as mentioned in brackets.Each must have a Makefile.am ready in them.

MAKEFILES: Each makefile.am should be as follows.In the source directory the Makefile is as follows:

bin_PROGRAMS = canvas
canvas_SOURCES = paint.cpp

The bin_PROGRAMS specifies the following binaries to be compiled and stored in the $PREFIX/bin directory.The _SOURCES specify the sources of the binaries.For the data directory the makefile should be as follows:

resdir = $(datarootdir)/@PACKAGE@
res_DATA = canvas.png chk.png crop.png curve.png erase.png ...

 We define a data directory according to the one used in the binary and the data files will be written to it.

COMMANDS: Once these files are ready run the following commands in order:
* aclocal
* automake --add-missing
* autoconf
* autoreconf -fvi
You will get your scripts.Run configure and make install to install.This project can be found in my github account :  https://github.com/saswatraj/Canvas

The simple types of javascript are : numbers , booleans , strings , null and undefined. All other types are objects in javascript. Hence a detailed knowledge is required for manipulating objects in javascript. Remember : Objects in javascript are class free. They are basically name value pairs surrounded by curly braces.Objects are always passed around by reference.

Initialization :

var empty_object = {}; 

var exobj = {

        'name':'saswat',

        'occupation':'student'

       };

Retireval :

exobj['name'] //returns 'saswat'

exobj.name    //preferred and more cleaner

exobj.status  // not present hence returns undefined

For filling in default values for undefined objects use the '||' operator.Attempting to retrieve values from undefined will throw a TypeError exception.

Updation :

Updation can be done by the assignment operator. If the object does not have the property name then it is augmented to the property names present with the value that is assigned.

Prototype :

Every object in javascript inherits properties from some other object. All objects created directly inherit from the Object.prototype an object that comes along with javascript.

If we try to retrieve a value from an object and that property is not present javascript tries to retrieve the property from the obejcts prototype and then from the prototype of the prototype and so on till it reaches the Object.prototype. If it is found nowhere in the chain then it is undefined.This is called delegation in javascript.

A detailed description on Prototype will be provided in the next few platters of  inheritance in javascript.However for now we can use Object.create function which takes a prototype from which to derive the new Object. One can also assign the protoype property with an object . i.e.

exobj.prototype = new User() ; //user as prototype object

exobj.prototype = Object.create(User.prototype);

The difference between the two is that in Object.create the constructor is not called hence the object remains uninitialized.

If we add a new property to the prototype then the new property will show in each object derived from that prototype.

But then how do we know whether the property belongs to the object or to the prototype chain.This can be known by using the hasOwnProperty which does not look into the property chain.For example:

exobj.hasOwnProperty('name') //true

exobj.hasOwnProperty('constructor') //false

Enumeration :

For enumerating the properties of the object use the for in construct .This includes the prototype chain properties.Hence we need to filter using typeof and hasOwnProperty. Careful Note :: The elements can come in any order.

for ( property in exobj ){

    if( exobj.hasOwnProperty(property) && typeof exobj[property] == 'string')

      //do something

} 

Deletion : The delete operator can be used to remove a property from object. Deleting may allow the prototype property to be accessible.