SWIG Python Examples

The following examples illustrate the use of SWIG with Python.

• simple. A minimal example showing how SWIG can be used to wrap a C function, a global variable, and a constant.
• constants. This shows how preprocessor macros and certain C declarations are turned into constants.
• variables. An example showing how to access C global variables from Python.
• value. How to pass and return structures by value.
• class. Wrapping a simple C++ class.
• reference. C++ references.
• pointer. Simple pointer handling.
• funcptr. Pointers to functions.

Compilation Issues

• To create a Python extension, SWIG is run with the following options:

  % swig -python interface.i
  

• Please see the Windows page in the main manual for information on using the examples on Windows.

• On Unix the compilation of examples is done using the file Example/Makefile. This makefile performs a manual module compilation which is platform specific. Typically, the steps look like this (Linux):

  % swig -python interface.i
  % gcc -fpic -c interface_wrap.c -I/usr/local/include/python1.5
  % gcc -shared interface_wrap.o $(OBJS) -o interfacemodule.so 
  % python
  Python 1.5.2 (#3, Oct  9 1999, 22:09:34)  [GCC 2.95.1 19990816 (release)] on linux2
  Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam
  >>> import interface
  >>> interface.blah(...)
  ...
  

• The politically "correct" way to compile a Python extension is to follow the steps described at www.python.org or in the most excellent (and shamelessly plugged) Python Essential Reference:
  1. Create a file called Setup that looks like the following where $(SRCS) is filled in with any other source files you need to build the extension:

     *shared*
     interface interface_wrap.c $(SRCS)
     

  2. Copy the file Makefile.pre.in from the Python distribution. Usually it's located in the directory /usr/local/lib/python1.5/config on a Unix machine.

  3. Type the following to build the extension:

     % make -f Makefile.pre.in boot
     % make
     

  4. And that's it. If you are preparing an extension for distribution, you may want to look at the distutils.

Compatibility

• Linux
• Solaris

• Sparc Solaris 2.8.
• gcc-2.95.2
• Python 1.6b1.