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| <head> |
| <title>SWIG:Examples:python:simple</title> |
| </head> |
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| <body bgcolor="#ffffff"> |
| |
| |
| <tt>SWIG/Examples/python/simple/</tt> |
| <hr> |
| |
| <H2>Simple Python Example</H2> |
| |
| <p> |
| This example illustrates how you can hook Python 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 -python <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>examplemodule.so</tt>. |
| </ol> |
| |
| <h2>Using the extension</h2> |
| |
| Click <a href="example.py">here</a> to see a script that calls our C functions from Python. |
| |
| <h2>Key points</h2> |
| |
| <ul> |
| <li>Use the <tt>import</tt> statement to load your extension module from Python. For example: |
| <blockquote> |
| <pre> |
| import example |
| </pre> |
| </blockquote> |
| |
| <li>C functions work just like Python functions. For example: |
| <blockquote> |
| <pre> |
| g = example.gcd(42,105) |
| </pre> |
| </blockquote> |
| |
| <li>C global variables are accessed through a special variable called 'cvar'. For example: |
| <blockquote> |
| <pre> |
| a = example.cvar.Foo |
| </pre> |
| </blockquote> |
| </ul> |
| |
| <hr> |
| </body> |
| </html> |
