If it's any help, I wrote a small bit on the details of writing converters. It might help clarify some of the mechanics which, I agree, are a bit mysterious:
http://misspent.wordpress.com/2009/09/27/how-to-write-boost-python-converters/ Austin On Wed, Sep 30, 2009 at 11:40 PM, James Amundson <amund...@fnal.gov> wrote: > Hi, > > I'm trying to write to/from type converters for my code, and I'm stuck. My > case doesn't map well to any of those in the boost python documentation. I'm > trying to pass objects of type MPI_Comm (really a C type!) back and forth > with mpi4py (which uses cython internally.) The mpi4py author has provided a > working example using manual wrapping. I am attaching it to the end of this > message. On the C++ side I can extract a point to the MPI_Comm object from a > Python object like so: > > PyObject* py_obj; > // obviously, the value of py_obj has to be set somewhere... > MPI_Comm *comm_p = PyMPIComm_Get(py_obj); > > I thought it would be simple to write a type converter to do that, but I > don't understand the mechanics. This example doesn't seem to map onto the > lvalue_from_pytype paradigm, or the scitbx container_conversion paradigm. > > Any suggestions? > > Thanks, > Jim Amundson > > ----------------------------------- > // working example with manual conversion > > #include <mpi.h> > #include <iostream> > > static void sayhello(MPI_Comm comm) > { > if (comm == MPI_COMM_NULL) { > std::cout << "You passed MPI_COMM_NULL !!!" << std::endl; > return; > } > int size; > MPI_Comm_size(comm, &size); > int rank; > MPI_Comm_rank(comm, &rank); > int plen; char pname[MPI_MAX_PROCESSOR_NAME]; > MPI_Get_processor_name(pname, &plen); > std::cout << > "Hello, World! " << > "I am process " << rank << > " of " << size << > " on " << pname << > "." << std::endl; > } > > > #include <boost/python.hpp> > #include <mpi4py/mpi4py.h> > using namespace boost::python; > > static void hw_sayhello(object py_comm) > { > PyObject* py_obj = py_comm.ptr(); > MPI_Comm *comm_p = PyMPIComm_Get(py_obj); > if (comm_p == NULL) throw_error_already_set(); > sayhello(*comm_p); > } > > BOOST_PYTHON_MODULE(helloworld) > { > if (import_mpi4py() < 0) return; /* Python 2.X */ > > def("sayhello", hw_sayhello); > } > > > > _______________________________________________ > Cplusplus-sig mailing list > Cplusplus-sig@python.org > http://mail.python.org/mailman/listinfo/cplusplus-sig > _______________________________________________ Cplusplus-sig mailing list Cplusplus-sig@python.org http://mail.python.org/mailman/listinfo/cplusplus-sig
