Executive Summary

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<img src="images/exec.png" alt="Executive Summary">

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<em>
"Don't keep doing what doesn't work" -- Anonymous
<br>
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"Keep it simple stupid" -- Anonymous
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</em>
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<p>
SWIG is an interface compiler that connects programs written in C,
C++, and Objective-C with scripting languages including <a href="http://www.perl.org">Perl</a>,
<a href="http://www.python.org">Python</a>, and 
<a href="http://www.scriptics.com">Tcl/Tk</a>.  It works by taking the declarations commonly found in C/C++ header
files and using them to generate the glue code (wrappers) that scripting
languages need to access the underlying C/C++ code.

<p>
John Ousterhout has written an excellent 
<a href="http://www.scriptics.com/people/john.ousterhout/scripting.html">paper</a>
that describes the
benefits of scripting languages.   SWIG makes it even easier to
use scripting languages by automating the process of connecting scripting
languages to C/C++ code.

<p>SWIG is used in a number of ways:

<ul>
<li><b>Building better C/C++ programs</b>.   Using SWIG, you can easily replace the main()
function of a C program with a scripting interpreter.   This adds flexibility,
simplifies development, and makes it easier to build extensible applications.
When used with Tk, it also becomes possible to build simple graphical user interfaces.

<p>
<li><b>Rapid prototyping and debugging</b>.  SWIG allows C/C++ programs to be placed in
a scripting environment that can be used for testing and debugging.
For example, you might test a library with a collection of scripts or use the scripting
interpreter as an interactive debugger.   Since SWIG requires no modifications to the
underlying C code, it can be used even if the final product does not rely upon scripting.

<p>
<li><b>Systems integration</b>.  Scripting languages excel at controlling and gluing
software components together.  With SWIG, different C/C++ programs can be turned into
scripting language extension modules.   These modules can then be combined together
to create new and interesting applications.
</ul>

SWIG is sometimes compared to other scripting language extension building tools
and compilers for interface definition languages (IDL) such as CORBA IDL.
However, SWIG has a number of distinguishing features.

<p>
<ul>
<li><b>ANSI C/C++ syntax</b>.  SWIG parses a form of ANSI C 
syntax that has been extended with a number of special directives.
This makes it extremely easy to use since scripting interfaces
can usually be built by grabbing a header file and tweaking
it a little bit.

<p>
<li><b>Complete automation</b>.  SWIG produces a fully functional
scripting language module and is not a stub-generator.  It is rarely necessary to modify the output of SWIG.

<p>
<li><b>Multiple languages</b>.  SWIG can produce extension modules
for a variety of different scripting languages.  Most scripting language
extension building tools are specific to a single language.

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<li><b>Designed to work with existing C/C++ code</b>.  SWIG requires little, if any, modifications
to existing code.  Nor is it necessary to create special wrappers or stubs.
This allows existing applications to be easily migrated to a scripting interface.
It also allows you to maintain a clean separation  of the C/C++ implementation and its 
(often optional) scripting interface.

<p>
<li><b>Extensibility</b>.   SWIG gives you the full power to shoot
yourself in the foot.  It can be extended and customized in any number
of interesting ways.  Since C/C++ applications vary widely, SWIG is
designed to be adaptable to your application, not the other way around.
</ul>

A number of <a href="doc.html">papers and tutorials</a> describing SWIG are available.
You can also view a simple <a href="tutorial.html">tutorial</a> to see an
example of SWIG in action.

<p>
Find out <a href="projects.html">who</a> is using SWIG and what
they <a href="propaganda.html">said</a> about it (from the March, 1998
user survey).