| <html> |
| <head> |
| <title>SWIG:Examples:tcl:simple</title> |
| </head> |
| |
| <body bgcolor="#ffffff"> |
| |
| <tt>SWIG/Examples/tcl/simple/</tt> |
| <hr> |
| |
| <H2>Simple Tcl Example</H2> |
| |
| <p> |
| This example illustrates how you can hook Tcl 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 -tcl <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="runme.tcl">here</a> to see a script that calls our C functions from Tcl. |
| |
| <h2>Key points</h2> |
| |
| <ul> |
| <li>Use the <tt>load</tt> statement to load your extension module into Tcl. For example: |
| <blockquote> |
| <pre> |
| load ./example.so |
| </pre> |
| </blockquote> |
| |
| <li>C functions work just like Tcl functions. For example: |
| <blockquote> |
| <pre> |
| set g [gcd 42 105] |
| </pre> |
| </blockquote> |
| |
| <li>C global variables are accessed as Tcl variables. For example: |
| <blockquote> |
| <pre> |
| set a $Foo |
| set Foo $newvalue |
| </pre> |
| </blockquote> |
| </ul> |
| |
| <hr> |
| </body> |
| </html> |
