libs/python/test/embedding.cpp
// Copyright David Abrahams 2002. Permission to copy, use,
// modify, sell and distribute this software is granted provided this
// copyright notice appears in all copies. This software is provided
// "as is" without express or implied warranty, and with no claim as
// to its suitability for any purpose.
// embedded_hello -- A simple Boost.Python embedding example -- by
// Dirk Gerrits
#include <boost/python.hpp>
#include <boost/scoped_ptr.hpp>
#include <iostream>
#include <stdexcept>
#include <cassert>
namespace python = boost::python;
// An abstract base class
class Base : public boost::noncopyable
{
public:
virtual ~Base() {};
virtual std::string hello() = 0;
};
// C++ derived class
class CppDerived : public Base
{
public:
virtual ~CppDerived() {}
std::string hello()
{
return "Hello from C++!";
}
};
// Familiar Boost.Python wrapper class for Base
struct BaseWrap : public Base
{
BaseWrap(PyObject* self_)
: self(self_) {}
std::string hello() { return python::call_method<std::string>(self, "hello"); }
PyObject* self;
};
// Pack the Base class wrapper into a module
BOOST_PYTHON_MODULE(embedded_hello)
{
python::class_<Base, BaseWrap, boost::noncopyable>("Base")
;
}
void test()
{
//- INITIALIZATION -----------------------------------------------------------//
// Register the module with the interpreter
if (PyImport_AppendInittab("embedded_hello", initembedded_hello) == -1)
throw std::runtime_error("Failed to add embedded_hello to the interpreter's "
"builtin modules");
// Initialize the interpreter
Py_Initialize();
// Retrieve the main module
python::object main_module = python::extract<python::object>(
PyImport_AddModule("__main__")
)();
// Retrieve the main module's namespace
python::object main_namespace(main_module.attr("__dict__"));
// Define the derived class in Python.
// (You'll normally want to put this in a .py file.)
python::handle<> result(
PyRun_String(
"from embedded_hello import * \n"
"class PythonDerived(Base): \n"
" def hello(self): \n"
" return 'Hello from Python!' \n",
Py_file_input, main_namespace.ptr(), main_namespace.ptr())
);
// Result is not needed
result.reset();
// Extract the raw Python object representing the just defined derived class
python::handle<> class_ptr(
PyRun_String("PythonDerived\n", Py_eval_input,
main_namespace.ptr(), main_namespace.ptr()) );
// Wrap the raw Python object in a Boost.Python object
python::object PythonDerived(class_ptr);
//- MAIN PROGRAM -------------------------------------------------------------//
// Creating and using instances of the C++ class is as easy as always.
CppDerived cpp;
std::cout << cpp.hello() << std::endl;
// But now creating and using instances of the Python class is almost
// as easy!
python::object py_base = PythonDerived();
Base& py = python::extract<Base&>(py_base)();
std::cout << py.hello() << std::endl;
}
int main()
{
if (python::handle_exception(test))
{
if (PyErr_Occurred())
PyErr_Print();
return 1;
}
return 0;
}
#include "module_tail.cpp"