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[section boost/python/copy_const_reference.hpp]
[section Class `copy_const_reference`]
`copy_const_reference` is a model of [link concepts.resultconverter.resultconvertergenerator_concept ResultConverterGenerator] which can be used to wrap C++ functions returning a reference-to-const type such that the referenced value is copied into a new Python object.
``
namespace boost { namespace python
{
struct copy_const_reference
{
template <class T> struct apply;
};
}}
``
[endsect]
[section Class `copy_const_reference` metafunctions]
``template <class T> struct apply``
[variablelist
[[Requires][`T` is `U const&` for some `U`.]]
[[Returns][`typedef to_python_value<T> type;`]]
]
[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]
|
