# SWIG Ruby Examples

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The following examples illustrate the use of SWIG with Ruby.

- 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 Ruby.
- 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.
- enum. Enumeration.

## Compilation Issues

- To create a Ruby extension, SWIG is run with the following options:

  >     % swig -ruby 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 -ruby interface.i
  >     % gcc -fpic -c interface_wrap.c -I/usr/local/lib/ruby/1.4/i686-linux
  >     % gcc -shared interface_wrap.o $(OBJS) -o interface.so
  >     % ruby
  >     require 'interface'
  >     Interface.blah(...)
  >     ...

- The politically "correct" way to compile a Ruby extension is to follow the steps described `README.EXT` in Ruby distribution:

  1. Create a file called `extconf.rb` that looks like the following:

     >     require 'mkmf'
     >     create_makefile('interface')

  2. Type the following to build the extension:

     >     % ruby extconf.rb
     >     % make

## Compatibility

The examples have been extensively tested on the following platforms:

- Linux

Your mileage may vary. If you experience a problem, please let us know by sending a message to swig-dev@cs.uchicago.edu.