class Sample
{
public:
	void ShowMessage(std::string msg)
	{
		printf("%s", msg);
	}
};

BOOST_PYTHON_MODULE(SampleModule)
{
	class_<Sample>("SampleClass")
		.def("ShowMessage", &Sample::ShowMessage);
}

int main(int argc, char* argv[])
{
	Py_Initialize();

	// Не знаю нунжно ли это ;)
	init_module_SampleModule();

	object main = import("__main__");
	object global(main.attr("__dict__"));
	
	try
	{
		object result = exec(
		"import SampleModule \n"
		"sample = SampleModule.SampleClass() \n"
		"sample.ShowMessage('Test string')",
		global);
	}
	catch(error_already_set) {
		PyErr_Print();
	}

	Py_Finalize();
	return 0;
}

Traceback (most recent call last):
  File "<string>", line 1, in <module>
ImportError: No module named SampleModule

class Sample
{
public:
    void ShowMessage(std::string msg)
    {
        printf("%s", msg);
    }
};

BOOST_PYTHON_MODULE(SampleModule)
{
    class_<Sample>("SampleClass")
        .def("ShowMessage", &Sample::ShowMessage);
}

int main(int argc, char* argv[])
{
    PyImport_AppendInittab("SampleModuke, init_module_SampleModule);
    Py_Initialize();

    // Не знаю нунжно ли это ;)
    // init_module_SampleModule();

    object main = import("__main__");
    object global(main.attr("__dict__"));
    
    try
    {
        object result = exec(
        "import SampleModule \n"
        "sample = SampleModule.SampleClass() \n"
        "sample.ShowMessage('Test string')",
        global);
    }
    catch(error_already_set) {
        PyErr_Print();
    }

    Py_Finalize();
    return 0;
}