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122 lines
4.1 KiB
C++
122 lines
4.1 KiB
C++
/*
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This example shows how to make an Extension Class "pickleable".
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For more information refer to boost/libs/python/doc/pickle.html.
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*/
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#include <string>
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#include <boost/python/class_builder.hpp>
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namespace python = boost::python;
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namespace { // Avoid cluttering the global namespace.
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// A friendly class.
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class world
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{
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public:
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world(const std::string& country) : secret_number(0) {
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this->country = country;
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}
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std::string greet() const { return "Hello from " + country + "!"; }
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std::string get_country() const { return country; }
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void set_secret_number(int number) { secret_number = number; }
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int get_secret_number() const { return secret_number; }
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private:
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std::string country;
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int secret_number;
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};
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// Support for pickle.
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python::ref world_getinitargs(const world& w) {
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python::tuple result(1);
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result.set_item(0, w.get_country());
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return result.reference(); // returning the reference avoids the copying.
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}
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python::ref world_getstate(python::tuple const & args,
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python::dictionary const & keywords);
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PyObject* world_setstate(python::tuple const & args,
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python::dictionary const & keywords);
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}
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BOOST_PYTHON_MODULE_INIT(pickle3)
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{
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try
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{
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// Create an object representing this extension module.
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python::module_builder this_module("pickle3");
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// Create the Python type object for our extension class.
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python::class_builder<world> world_class(this_module, "world");
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// Add the __init__ function.
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world_class.def(python::constructor<std::string>());
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// Add a regular member function.
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world_class.def(&world::greet, "greet");
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world_class.def(&world::get_secret_number, "get_secret_number");
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world_class.def(&world::set_secret_number, "set_secret_number");
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// Support for pickle.
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world_class.def(world_getinitargs, "__getinitargs__");
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world_class.def_raw(world_getstate, "__getstate__");
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world_class.def_raw(world_setstate, "__setstate__");
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world_class.getstate_manages_dict();
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}
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catch(...)
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{
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python::handle_exception(); // Deal with the exception for Python
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}
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}
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namespace {
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python::ref world_getstate(python::tuple const & args,
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python::dictionary const & keywords)
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{
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if(args.size() != 1 || keywords.size() != 0) {
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PyErr_SetString(PyExc_TypeError, "wrong number of arguments");
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throw boost::python::argument_error();
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}
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const world& w = args[0].get<const world&>();
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python::ref mydict(args[0].getattr("__dict__"));
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python::tuple result(2);
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// store the object's __dict__
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result.set_item(0, mydict);
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// store the internal state of the C++ object
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result.set_item(1, w.get_secret_number());
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return result.reference(); // returning the reference avoids the copying.
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}
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PyObject* world_setstate(python::tuple const & args,
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python::dictionary const & keywords)
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{
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if(args.size() != 2 || keywords.size() != 0) {
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PyErr_SetString(PyExc_TypeError, "wrong number of arguments");
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throw boost::python::argument_error();
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}
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world& w = args[0].get<world&>();
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python::ref mydict(args[0].getattr("__dict__"));
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const python::tuple& state(args[1].get<python::tuple>());
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if (state.size() != 2) {
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PyErr_SetString(PyExc_ValueError,
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"Unexpected argument in call to __setstate__.");
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throw python::error_already_set();
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}
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// restore the object's __dict__
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python::dictionary odict(mydict.get<python::dictionary>());
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const python::dictionary& pdict(state[0].get<python::dictionary>());
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python::list pkeys(pdict.keys());
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for (int i = 0; i < pkeys.size(); i++) {
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python::ref k(pkeys[i]);
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//odict[k] = pdict[k]; // XXX memory leak!
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odict[k] = pdict.get_item(k); // this does not leak.
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}
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// restore the internal state of the C++ object
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int number = state[1].get<int>();
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if (number != 42)
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w.set_secret_number(number);
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return python::detail::none();
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}
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}
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