boost:python does not return a pointer - c++

Question

I have a small Python module written in C++. This module compiles well and can be imported to Python without any errors. These are some snippets of the code:
//...multiple includes
typedef variant<sqlite3 **, ... other types> VariantData; //!ONE
class ORM{
//... private fields
public:
VariantData Connect(int idx){
if(idx == 0) {
sqlite3 * conn;
sqlite3_open("reestr.db", &conn);
return &conn; //!TWO
// how to return a pointer to conn ???
// am I doing it right ???
}
}
//... other methods
// Python stuff
BOOST_PYTHON_MODULE(corm){
to_python_converter<VariantData, variant_to_object>(); //!THREE
implicitly_convertible<sqlite3 **, VariantData>(); //!THREE
//other unimportant code
So, this code compiles without errors. But,please, pay attention to four lines of code, marked by ONE, TWO and THREE, since they are causing errors. In my interpretation at line ONE I define a variant datatype that can take different values with sqlite3 ** among them. At lines THREE I define Python stuff responsible for converting variables and passing them between C++ and Python. However, I get into trouble when I try to use this module in Python. I do it like:
>>> import corm
>>> c = corm.ORM(...initialization parameters...)
>>> r = c.Connect() # !ERROR
... No to_python (by-value) converter found for C++ type: sqlite *
I really wonder why Python is talking about sqlite * type here, while the method itself does return &conn; and so returns a variable of type sqlite3 ** (as I believe). So, in a nutshell, my question is how to return a pointer of type sqlite3 ** from Connect method.

Answer 1

This is a solution. I'm not sure whether it is good, but at least it works:
typedef variant<void *, ... other types> VariantData;
class ORM{
//... private fields
public:
VariantData Connect(int idx){
if(idx == 0) {
sqlite3 * conn;
sqlite3_open("reestr.db", &conn);
void * ref = ::operator new(sizeof(conn));
ref = conn;
return ref;
}
...
}
....
};
struct variant_to_object {
static PyObject* convert(VariantData const& v){
return boost::python::incref(
boost::python::object(v).ptr());
}
};
BOOST_PYTHON_MODULE(corm){
to_python_converter<VariantData, variant_to_object>();
implicitly_convertible<void *, VariantData>();
But of course, I should take care of ref pointer and delete it, when it is no longer used.