[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]