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- <html>
- <head>
- <title>SWIG:Examples:ruby:simple</title>
- </head>
- <body bgcolor="#ffffff">
- <tt>SWIG/Examples/ruby/simple/</tt>
- <hr>
- <H2>Simple Ruby Example</H2>
- <p>
- This example illustrates how you can hook Ruby to a very simple C program containing
- a function and a global variable.
- <h2>The C Code</h2>
- Suppose you have the following C code:
- <blockquote>
- <pre>
- /* File : example.c */
- /* A global variable */
- double Foo = 3.0;
- /* Compute the greatest common divisor of positive integers */
- int gcd(int x, int y) {
- int g;
- g = y;
- while (x > 0) {
- g = x;
- x = y % x;
- y = g;
- }
- return g;
- }
- </pre>
- </blockquote>
- <h2>The SWIG interface</h2>
- Here is a simple SWIG interface file:
- <blockquote>
- <pre>
- /* File: example.i */
- %module example
- extern int gcd(int x, int y);
- extern double Foo;
- </pre>
- </blockquote>
- <h2>Compilation</h2>
- <ol>
- <li><tt>swig -ruby <a href="example.i">example.i</a></tt>
- <p>
- <li>Compile <tt><a href="example_wrap.c">example_wrap.c</a></tt> and <tt><a href="example.c">example.c</a></tt>
- to create the extension <tt>example.so</tt>.
- </ol>
- <h2>Using the extension</h2>
- Click <a href="run.rb">here</a> to see a script that calls our C functions from Ruby.
- <h2>Key points</h2>
- <ul>
- <li>Use the <tt>require</tt> function to load your extension library from Ruby. For example:
- <blockquote>
- <pre>
- require 'example'
- </pre>
- </blockquote>
- <li>C functions work just like Ruby functions. For example:
- <blockquote>
- <pre>
- g = Example.gcd(42,105)
- </pre>
- </blockquote>
- <li>C global variables are accessed through module method. For example:
- <blockquote>
- <pre>
- a = Example.Foo
- </pre>
- </blockquote>
- </ul>
- <hr>
- </body>
- </html>