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- // Copyright Ralf W. Grosse-Kunstleve 2002-2004. 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)
- /*
- This example shows how to make an Extension Class "pickleable".
- The world class below contains member data (secret_number) that
- cannot be restored by any of the constructors. Therefore it is
- necessary to provide the __getstate__/__setstate__ pair of pickle
- interface methods.
- The object's __dict__ is included in the result of __getstate__.
- This requires more code (compare with pickle2.cpp), but is
- unavoidable if the object's __dict__ is not always empty.
- For more information refer to boost/libs/python/doc/pickle.html.
- */
- #include <boost/python/module.hpp>
- #include <boost/python/def.hpp>
- #include <boost/python/class.hpp>
- #include <boost/python/tuple.hpp>
- #include <boost/python/dict.hpp>
- #include <boost/python/extract.hpp>
- #include <boost/python/back_reference.hpp>
- namespace boost_python_test {
- // A friendly class.
- class world
- {
- public:
- world(const std::string& _country) : secret_number(0) {
- this->country = _country;
- }
- std::string greet() const { return "Hello from " + country + "!"; }
- std::string get_country() const { return country; }
- void set_secret_number(int number) { secret_number = number; }
- int get_secret_number() const { return secret_number; }
- private:
- std::string country;
- int secret_number;
- };
- struct world_pickle_suite : boost::python::pickle_suite
- {
- static
- boost::python::tuple
- getinitargs(const world& w)
- {
- return boost::python::make_tuple(w.get_country());
- }
- static
- boost::python::tuple
- getstate(boost::python::object w_obj)
- {
- world const& w = boost::python::extract<world const&>(w_obj)();
- return boost::python::make_tuple(
- w_obj.attr("__dict__"),
- w.get_secret_number());
- }
- static
- void
- setstate(boost::python::object w_obj, boost::python::tuple state)
- {
- using namespace boost::python;
- world& w = extract<world&>(w_obj)();
- if (len(state) != 2)
- {
- PyErr_SetObject(PyExc_ValueError,
- ("expected 2-item tuple in call to __setstate__; got %s"
- % state).ptr()
- );
- throw_error_already_set();
- }
- // restore the object's __dict__
- dict d = extract<dict>(w_obj.attr("__dict__"))();
- d.update(state[0]);
- // restore the internal state of the C++ object
- long number = extract<long>(state[1]);
- if (number != 42)
- w.set_secret_number(number);
- }
- static bool getstate_manages_dict() { return true; }
- };
- }
- BOOST_PYTHON_MODULE(pickle3_ext)
- {
- using namespace boost_python_test;
- boost::python::class_<world>(
- "world", boost::python::init<const std::string&>())
- .def("greet", &world::greet)
- .def("get_secret_number", &world::get_secret_number)
- .def("set_secret_number", &world::set_secret_number)
- .def_pickle(world_pickle_suite())
- ;
- }
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