How to switch to C ++ code when debugging python using DDD (or gdb)

Question

In the test case, I have this C ++ test class that I exported to Python using boost. (from boost site)

#include <boost/python.hpp>
using namespace boost::python;

struct WorldC
{
    void set(std::string msg) { this->msg = msg; }
    std::string greet() { return msg; }
    std::string msg;
};

BOOST_PYTHON_MODULE(hello)
{
    class_<WorldC>("WorldP")
        .def("greet", &WorldC::greet)
        .def("set", &WorldC::set)
    ;
}

I compiled this code g++ -g -shared -o hello.so -fPIC hello.cpp -lboost_python -lpython2.7 -I/usr/local/include/python2.7and tested it in order. The test script pp1.pylooks like this:

import hello
a = hello.WorldP()
a.set('ahahahah')    # <-- line 3
print a.greet()
print('print1')
b = hello.WorldP()
b.set('bhbhbhbh')
print b.greet()
print('print2')
print('program done')

This code works fine either interactively or as a script.

ckim@stph45:~/python/hello] python pp1.py
ahahahah
print1
bhbhbhbh
print2
program done

DDD . ddd -pydb pp1.py, Python. , next . , , 3, step, , ++. ? ( gdb, , ++.)