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