[C++-sig] passing wrapped c++ objects to boost wrapped function

[Kim Branson]

I'm attempting to extract the underlying OEMol object, from the  
PySwigObject.
The extract<int> wont work, since i need to use more complex  
functionality from the OEMol in the c++ classes i'm attempting to  
pass the OEMol to.

I found some stuff on the wiki which indicated that the below might  
work.  I'm unclear on what exactly the type that finalBondIndex gets  
passed.
I thought the code below would take a PySwigObject and return a  
pointer  of type OEChem::OEMol,   and then my other code would then  
get a reference to the OEChem::OEMol object that the PySwigObject  
refers to?

Or is it more complicated than  this?  if a print a mol i get  
<openeye.oechem.OEMol; proxy of C++ OEMolWrapper instance at  
_a0386400_p_OEMolWrapper>, does that mean the type is a OEMolWrapper  
instance and i should register that as a type?

cheers

Kim

++++++++++++++++++++++++++++++++++++++
#include "functions.h"
#include "python.h"
#include <boost/python/module.hpp>
#include <boost/python/def.hpp>
//#include "swig_arg.hpp"
using namespace boost::python;

typedef struct {
     PyObject_HEAD
     void *ptr;
     const char *desc;
} PySwigObject;

void* extract_swig_wrapped_pointer(PyObject* obj)
{
     char thisStr[] = "this";
     //first we need to get the this attribute from the Python Object
     if (!PyObject_HasAttrString(obj, thisStr))
         return NULL;

     PyObject* thisAttr = PyObject_GetAttrString(obj, thisStr);
     if (thisAttr == NULL)
         return NULL;
     //This Python Object is a SWIG Wrapper and contains our pointer
     return (((PySwigObject*)thisAttr)->ptr);
};



int  finalBondIndex(OEMol &mol)
{
     int numOfBonds = 0 ;
     int index =0 ;

     OEIter<OEBondBase> bond;
     for ( bond=mol.GetBonds(); bond; ++bond ) {
         index = bond->GetEndIdx();
         numOfBonds++;
     }
     return index ;
};


BOOST_PYTHON_MODULE(test)
{
     boost::python::converter::registry::insert 
(&extract_swig_wrapped_pointer, type_id<OEMol>());

     //BOOST_PYTHON_SWIG_ARG(OEMol)
     def("finalBondIndex",finalBondIndex);
}


I run this like so
++++++++++++++++++++++++++++++++++++++
#!/usr/bin/python
from openeye.oechem import *
import test
mol = OEMol()
print "mol is ",mol
print type(mol)
ifs = oemolistream("ligand.mol2")
OEReadMolecule(ifs,mol)
print "loaded mol"
print "loaded mol is ",mol
numbonds =0
print "Call test.finalBondIndex with no arguments"
try:
     numbonds = test.finalBondIndex()
except TypeError, e:
     print "Caught exception ",e
print "Call test.finalBondIndex with OEMol argument"
try:
     numbonds = test.finalBondIndex(mol.this)
     print("Number of bonds is %i  \n" %(numbonds))
except TypeError, e:
     print "Caught exception ",e

and get the following result:
++++++++++++++++++++++++++++++++++++++
mol is  <openeye.oechem.OEMol; proxy of C++ OEMolWrapper instance at  
_a0386400_p_OEMolWrapper>
<class 'openeye.oechem.OEMol'>
loaded mol
loaded mol is  <openeye.oechem.OEMol; proxy of C++ OEMolWrapper  
instance at _a0386400_p_OEMolWrapper>
Call test.finalBondIndex with no arguments
Caught exception  Python argument types in
     test.finalBondIndex()
did not match C++ signature:
     finalBondIndex(OEChem::OEMol {lvalue})
Call test.finalBondIndex with OEMol argument
Caught exception  Python argument types in
     test.finalBondIndex(PySwigObject)
did not match C++ signature:
     finalBondIndex(OEChem::OEMol {lvalue})


On Jan 5, 2007, at 6:25 AM, Son, Serguei wrote:

> int numberOfAtoms(object mol)
> {
> 	int numAtoms = extract<int>(mol.attr("name")());
> 	return numAtoms;
> }

Dr Kim Branson, PhD
Stanford University, Stanford, CA, USA
Department of Chemistry, Group of Prof. Dr. V. Pande
Postdoctoral Fellow: Folding at home - distributed computing
Clark Center, 94305-5080 Stanford, CA, phone: (650) 723 1817
email kim.branson at stanford.edu

"I cook with wine, sometimes i even add it to the food" -- WC Fields