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- [section boost/python/return_value_policy.hpp]
- [section Introduction]
- return_value_policy instantiations are simply models of [link concepts.callpolicies `CallPolicies`] which are composed of a [link concepts.resultconverter.resultconvertergenerator_concept `ResultConverterGenerator`] and optional `Base` [link concepts.callpolicies `CallPolicies`].
- [endsect]
- [section Class template `return_value_policy`]
- [table
- [[Parameter][Requirements][Default]]
- [[ResultConverterGenerator][A model of [link concepts.resultconverter.resultconvertergenerator_concept `ResultConverterGenerator`]][]]
- [[Base][A model of [link concepts.callpolicies `CallPolicies`]][default_call_policies]]
- ]
- ``
- namespace boost { namespace python
- {
- template <class ResultConverterGenerator, class Base = default_call_policies>
- struct return_value_policy : Base
- {
- typedef ResultConverterGenerator result_converter;
- };
- }}
- ``
- [endsect]
- [section Example]
- C++ module definition:
- ``
- #include <boost/python/module.hpp>
- #include <boost/python/class.hpp>
- #include <boost/python/copy_const_reference.hpp>
- #include <boost/python/return_value_policy.hpp>
- // classes to wrap
- struct Bar { int x; }
- struct Foo {
- Foo(int x) : { b.x = x; }
- Bar const& get_bar() const { return b; }
- private:
- Bar b;
- };
- // Wrapper code
- using namespace boost::python;
- BOOST_PYTHON_MODULE(my_module)
- {
- class_<Bar>("Bar");
- class_<Foo>("Foo", init<int>())
- .def("get_bar", &Foo::get_bar
- , return_value_policy<copy_const_reference>())
- ;
- }
- ``
- Python code:
- ``
- >>> from my_module import *
- >>> f = Foo(3) # create a Foo object
- >>> b = f.get_bar() # make a copy of the internal Bar object
- ``
- [endsect]
- [endsect]
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