[C++-sig] return PyObject* failed.

[Qinfeng(Javen) Shi]

Dear all,

I write a c extension function to access python list.
I can visit the list by PyObject* a, but failed when I tried to return
PyObject* to python.
Any suggestion will be appreciated.

>>> list1 = range(5);
>>> rlist = hello.testList(list1)
4 3 2 1 0 size:5
b is list type!                                   # seems right now.
>>> rlist                                         # but actually it
crashed when display the returned rlist
Segmentation fault


/**************c extension************/
static PyObject * testList(PyObject* a)
{
   if(!(PyList_Check(a)))
   {
	printf("not list type!\n");
	return NULL;
   }
   int num = PyList_Size(a);
   PyList_Reverse(a);
   // modify a.
    for(int i=0;i<num;i++)
    {
        printf("%d ",PyInt_AsLong(PyList_GetItem(a,i)));      // print
it out
    }
    printf("size:%d\n",num);

	PyObject * b = PyList_New(10);                             // create
a new list b
        if (b == NULL)
		return NULL;
    if(!(PyList_Check(b)))
     // check b
    {
	printf("b is not list type!\n");
	return NULL;
    }
    else
    {
         printf("b is list type!\n");
    }
    /**********************works untill now******************/
    return (PyObject *)b; /***********failed**/ // return b. in
fact,if return a, it also crashed
}


// Boost Includes ==============================================================
#include <boost/python.hpp>
#include <boost/cstdint.hpp>

// Includes ====================================================================
#include <hello.c>

// Using =======================================================================
using namespace boost::python;

// Declarations ================================================================
BOOST_PYTHON_OPAQUE_SPECIALIZED_TYPE_ID(PyObject)


// Module ======================================================================
BOOST_PYTHON_MODULE(hello)
{
    def("main", &main);
    def("testList", &testList, return_value_policy< return_opaque_pointer >());
}









-- 
Qinfeng(Javen) Shi

Research School of Information Sciences and Engineering
Australian National University
Locked Bag 8001
Canberra ACT 2601