98 lines
2.9 KiB
C++
98 lines
2.9 KiB
C++
// Copyright Ralf W. Grosse-Kunstleve 2002-2004. Distributed under the Boost
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// Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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/*
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This example shows how to make an Extension Class "pickleable".
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The world class below contains member data (secret_number) that
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cannot be restored by any of the constructors. Therefore it is
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necessary to provide the __getstate__/__setstate__ pair of pickle
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interface methods.
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For simplicity, the __dict__ is not included in the result of
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__getstate__. This is not generally recommended, but a valid
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approach if it is anticipated that the object's __dict__ will
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always be empty. Note that safety guards are provided to catch
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the cases where this assumption is not true.
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pickle3.cpp shows how to include the object's __dict__ in the
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result of __getstate__.
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For more information refer to boost/libs/python/doc/pickle.html.
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*/
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#include <boost/python/module.hpp>
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#include <boost/python/def.hpp>
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#include <boost/python/class.hpp>
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#include <boost/python/tuple.hpp>
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#include <boost/python/extract.hpp>
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namespace boost_python_test {
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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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struct world_pickle_suite : boost::python::pickle_suite
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{
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static
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boost::python::tuple
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getinitargs(const world& w)
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{
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return boost::python::make_tuple(w.get_country());
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}
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static
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boost::python::tuple
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getstate(const world& w)
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{
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return boost::python::make_tuple(w.get_secret_number());
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}
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static
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void
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setstate(world& w, boost::python::tuple state)
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{
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using namespace boost::python;
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if (len(state) != 1)
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{
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PyErr_SetObject(PyExc_ValueError,
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("expected 1-item tuple in call to __setstate__; got %s"
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% state).ptr()
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);
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throw_error_already_set();
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}
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long number = extract<long>(state[0]);
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if (number != 42)
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w.set_secret_number(number);
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}
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};
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}
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BOOST_PYTHON_MODULE(pickle2_ext)
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{
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using namespace boost_python_test;
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boost::python::class_<world>(
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"world", boost::python::init<const std::string&>())
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.def("greet", &world::greet)
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.def("get_secret_number", &world::get_secret_number)
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.def("set_secret_number", &world::set_secret_number)
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.def_pickle(world_pickle_suite())
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;
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}
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