Boost.Python

Contents

Classes

Class copy_const_reference

Class copy_const_reference synopsis

Class copy_const_reference metafunctions

Example

Classes

Class copy_const_reference

copy_const_reference is a model of 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.

Class copy_const_reference synopsis

namespace boost { namespace python
{
    struct copy_const_reference
    {
        template <class T> struct apply;
    };
}}

Class copy_const_reference metafunctions

template <class T> struct apply

Requires: T is U const& for some U.

Returns: typedef to_python_value<T> type;

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_INIT(my_module)
{
   module m("my_module")
      .add(
         class_<Bar>()
         )
      .add(
         class_<Foo>()
            .def_init(args<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

Revised 15 February, 2002

© Copyright Dave Abrahams 2002. All Rights Reserved.