This is a code snippet that exports an existing Cpp object to python

cpp-object-to-python.cpp

#include <iostream>
#include <string>

#include <boost/python.hpp>

using namespace std;
using namespace boost::python;

class World
{
private:
    string name;
public:
    World() {}
    void set(string name) {
        this->name = name;
    }
    void greet() {
        cout << "hello, I am " << name << endl;
    }
};

typedef std::shared_ptr< World > world_ptr;

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

int main()
{
    Py_Initialize();

    inithello();

    object main_module = import("__main__");
    object main_namespace = main_module.attr("__dict__");

    std::shared_ptr<World> w = std::make_shared<World>();
    main_namespace["world"] = ptr(w.get());

    object ignored = exec("world.set('python')\n"
                          "world.greet()", main_namespace, main_namespace);

    return 0;
}

Based on https://wiki.python.org/moin/boost.python/EmbeddingPython