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// Copyright David Abrahams 2002.
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
// 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");
// Retrieve the main module
python::object main_module((
python::handle<>(python::borrowed(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)
#if BOOST_WORKAROUND(BOOST_MSVC, <= 1300) || BOOST_WORKAROUND(BOOST_INTEL_WIN, <= 900)
()
#endif
;
std::cout << py.hello() << std::endl;
}
void
test_tutorial()
{
using namespace boost::python;
object main_module((
handle<>(borrowed(PyImport_AddModule("__main__")))));
object main_namespace = main_module.attr("__dict__");
handle<> ignored((PyRun_String(
"hello = file('hello.txt', 'w')\n"
"hello.write('Hello world!')\n"
"hello.close()"
, Py_file_input
, main_namespace.ptr()
, main_namespace.ptr())
));
}
void
test_tutorial2()
{
using namespace boost::python;
object main_module((
handle<>(borrowed(PyImport_AddModule("__main__")))));
object main_namespace = main_module.attr("__dict__");
handle<> ignored((PyRun_String(
"result = 5 ** 2"
, Py_file_input
, main_namespace.ptr()
, main_namespace.ptr())
));
int five_squared = extract<int>(main_namespace["result"]);
assert(five_squared == 25);
object result((handle<>(
PyRun_String("5 ** 2"
, Py_eval_input
, main_namespace.ptr()
, main_namespace.ptr()))
));
int five_squared2 = extract<int>(result);
assert(five_squared2 == 25);
}
int main()
{
// Initialize the interpreter
Py_Initialize();
if (python::handle_exception(test))
{
if (PyErr_Occurred())
PyErr_Print();
return 1;
}
if (python::handle_exception(test_tutorial))
{
if (PyErr_Occurred())
PyErr_Print();
return 1;
}
if (python::handle_exception(test_tutorial2))
{
if (PyErr_Occurred())
PyErr_Print();
return 1;
}
// Boost.Python doesn't support Py_Finalize yet.
// Py_Finalize();
return 0;
}
#include "module_tail.cpp"
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