SWIG python module creation issue - c++

Question

I have c++ classes that are needed to import in python.
For that I am using SWIG. Below is the swig interface
example.i
/* File: example.i */
%module example
%{
#include "Item.h"
#include "GradedDouble.h"
#include "GradedComplex.h"
%}
%include <std_string.i>
%include <std_complex.i>
%include "Item.h"
%include "GradedDouble.h"
%include "GradedComplex.h"
%template(Int) Item<int>;
%template(Complex) Item<std::complex<double> >;
And for creating wrapper class and python module I am executing following command in windows XP environment
c:\>swig -c++ -python -nodefaultctor example.i
c:\>python setup.py build_ext --inplace
After executing second command I am getting the following error :
*C:\Program Files\Microsoft Visual Studio 9.0\VC\BIN\link.exe /DLL /nologo /INCREMENTAL:NO /LIBPATH:C:\Python26\libs /LIBPATH:C:\Python26\PCbuild /EXPORT:init_example build\temp.win32-2.6\Release\example_wrap.obj "/OUT:C:\Documents and Settings\swig_example.pyd" /IMPLIB:build\temp.win32-2.6\Release\_example.lib /MANIFESTFILE:build\temp.win32-2.6\Release\_example.pyd.manifest
Creating library build\temp.win32-2.6\Release\_example.lib and object build\temp.win32-2.6\Release\_example.exp
example_wrap.obj : error LNK2019: unresolved external symbol "public: __thiscall GradedDouble::~GradedDouble(void)" (??1GradedDouble##QAE#XZ) referenced in function __wrap_delete_GradedDouble
example_wrap.obj : error LNK2019: unresolved external symbol "public: __thiscall GradedComplex::~GradedComplex(void)" (??1GradedComplex##QAE#XZ) referenced in function __wrap_delete_GradedComplex
example_wrap.obj : error LNK2019: unresolved external symbol "public: __thiscall GradedDouble::GradedDouble(int,double *)" (??0GradedDouble##QAE#HPAN#Z) referenced in function __wrap_new_GradedDouble
example_wrap.obj : error LNK2019: unresolved external symbol "public: void __thiscall GradedDouble::avg(double *)" (?avg#GradedDouble##QAEXPAN#Z) referenced in function __wrap_GradedDouble_avg
example_wrap.obj : error LNK2019: unresolved external symbol "public: __thiscall GradedComplex::GradedComplex(int,double *)" (??0GradedComplex##QAE#HPAN#Z) referenced in function __wrap_new_GradedComplex
example_wrap.obj : error LNK2019: unresolved external symbol "public: void __thiscall GradedComplex::avg(double *)" (?avg#GradedComplex##QAEXPAN#Z) referenced in function __wrap_GradedComplex_avg
example_wrap.obj : error LNK2019: unresolved external symbol "public: void __thiscall GradedComplex::push(class Item<class std::complex<double> >)" (?push#GradedComplex##QAEXV?$Item#V?$complex#N#std#####Z) referenced in function __wrap_GradedComplex_push
example_wrap.obj : error LNK2019: unresolved external symbol "public: void __thiscall GradedDouble::push(class Item<double>)" (?push#GradedDouble##QAEXV?$Item#N###Z) referenced in function __wrap_GradedDouble_push
C:\Documents and Settings\swig_example.pyd : fatal error LNK1120: 8 unresolved externals
error: command '"C:\Program Files\Microsoft Visual Studio 9.0\VC\BIN\link.exe"'failed with exit status 1120*
It seems there are issue in creating interface file of swig (example.i)
I need help for creating interface file. Following are the header files
GradedComplex.h
#ifndef __GRADEDCOMPLEX_H__
#define __GRADEDCOMPLEX_H__
#include <complex>
#include <set>
#include <vector>
#include "Item.h"
class GradedComplex
{
public:
typedef std::complex<double> dcomplex;
typedef Item<dcomplex> item_type;
typedef ItemComparator<dcomplex> comparator;
typedef std::set<item_type, comparator> grade_type;
private:
int n_;
std::vector<grade_type *> grade_;
std::vector<double> thre_;
public:
GradedComplex(int n, double *thre);
~GradedComplex();
void push(item_type item);
void avg(double *buf);
};
#endif
Graded Double.h
#ifndef __GRADEDDOUBLE_H__
#define __GRADEDDOUBLE_H__
#include <set>
#include <vector>
#include "Item.h"
class GradedDouble
{
public:
typedef Item<double> item_type;
typedef ItemComparator<double> comparator;
typedef std::set<item_type, comparator> grade_type;
private:
int n_;
std::vector<grade_type *> grade_;
std::vector<double> thre_;
public:
GradedDouble(int n, double *thre);
~GradedDouble();
void push(item_type item);
void avg(double *buf);
};
#endif
Please help me for creating correct SWIG interface file.

Answer 1

It looks like the link operation is missing the definitions for your GradedDouble and GradedComplex classes.
You have to provide these definitions to the linker, either in the form of object files, or in the form of a library.
I don't know enough about SWIG on Windows (only use it on Linux) to be able to help further on how to solve this.