How do I expose my C++ type to a user defined python type? I think I could use
boost python class_<> wrapper to wrap around, but if I want to use
to_python/from_python convertors?
Say I want to expose my C++ class(CA) to a python type(PA):
C++:
class CA
{
public:
//ctors, accessors...
private:
std::string name_;
int value_;
};
Python:
class PA(object):
def __init__(self, name, value):
self.name=name
self.value=value
If I use,
void initializeConverters()
{
using namespace boost::python;
to_python_converter<CA, CA_to_pA>();
}
with
struct CA_to_PA
{
static PyObject* convert(CA const& s)
{
printf("In C++ -> python converter?\n");
std::string name=s.name();
int value=s.value();
#if 0
static boost::python::object obj;
PyObject* obj_ptr=obj.ptr();
PyObject_SetAttrString(obj_ptr, "name",
PyString_FromString(name.c_str()));
PyObject_SetAttrString(obj_ptr, "value",
PyInt_FromLong(value));
return boost::python::incref(obj_ptr);
#else
return boost::python::incref(
//PyInt_FromLong(1999)
Py_BuildValue("s", "native string works")
//Py_BuildValue("{s:i,s:i}", "abc", 123, "def", 456)
);
#endif
}
};
How do I create a boost::python::object (or PyObject*) with "name" and "value"
attributes? I could get creation and return of python native types to work, but
can not get user defined types returned to the python side -- always get
NoneType returned.
boost::python::object C2Py()
{
printf("Pre assignment\n");
#if 0
boost::python::object obj(new CA("From C++ to python", 987654321));
PyObject* o=obj.ptr();
#else
CA a("From C++ to python", 987654321);
PyObject *o=CA_to_PA::convert(a);
#endif
printf("Post assignment\n");
PyObject *tmp=NULL;
std::string name="No Name";
int value=-1;
tmp=PyObject_GetAttrString(o, "name");
if (tmp!=NULL) name=PyString_AsString(tmp);
tmp=PyObject_GetAttrString(o, "value");
if (tmp!=NULL) value=PyInt_AsLong(tmp);
printf("(%s, %d)\n", name.c_str(), value);
return obj;
}
$ python
Python 2.5.1 (r251:54863, Oct 5 2007, 11:16:46)
[GCC 4.1.1 20070105 (Red Hat 4.1.1-53)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import mytypes
>>> pa=mytypes.C2Py()
("No Name", -1)
>>>type(pa)
NoneType
Any help is appreciated, thanks!
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