Swig

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Compiling a C++ example for python on mac os 10.6

  • learning_swig.i
/* File : learning_swig.i */

/* Use c-style comments, because these lines get copied into the generated
    c code */

/* module name specified by %module directive */
%module learning_swig
%{
/* The lines inside between the %{ }% aren't parsed by SWIG, but are copied verbatim
   into the wrapper c-code */
/* Put headers and other declarations here */

#include "learning_swig.hxx"

/* extern keyword is optional for function prototypes... */
extern void print_my_info( char * the_name, double the_age );

/* ...but is required for variables */
extern char * my_name;
extern double my_age;

%}
%include "learning_swig.hxx"

/* ANSI C/C++ declarations go here */

extern void print_my_info( char * the_name, double the_age );
extern char * my_name;
extern double my_age;
extern class person;
  • learning_swig.hxx

class person {
  public:
    person() : m_name( "Blank Person" ), m_age(-1) {}
    person( char * the_name, double the_age) : m_name( the_name ), m_age( the_age ) {}
    ~person() {}

    void print_all_info();

  private:
    char * m_name;
    double m_age;
};
  • learning_swig.cxx
#include <stdio.h>
#include "learning_swig.hxx"

char * my_name = "Chris Coletta";
double my_age = 28.9;


void print_my_info( char* the_name, double the_age ) {
  printf( "%s is %0.3f years old.\n", the_name, the_age );
}

void person::print_all_info()
{
  print_my_info( m_name, m_age );
}
  • compilation
swig -c++ -python learning_swig.i
g++ -c `python-config --cflags` learning_swig.cxx learning_swig_wrap.cxx
g++ -bundle `python-config --ldflags` learning_swig.o learning_swig_wrap.o -o _learning_swig.so
  • operation in ipython
import learning_swig
learning_swig.print_my_info( "poop", 70 )
print learning_swig.cvar.my_age
    • note: global variables are grouped into the "cvar" scope