Boost C++ Libraries of the most highly regarded and expertly designed C++ library projects in the world. Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

This is the documentation for an old version of boost. Click here for the latest Boost documentation.


Header <boost/python/return_by_value.hpp>


Class return_by_value
Class return_by_value synopsis
Class return_by_value metafunctions


Class return_by_value

return_by_value is a model of ResultConverterGenerator which can be used to wrap C++ functions returning any reference or value type such that the return value is copied into a new Python object.

Class return_by_value synopsis

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

Class return_by_value metafunctions

template <class T> struct apply
Returns: typedef to_python_value<T> type;


C++ Module Definition

#include <boost/python/module.hpp>
#include <boost/python/class.hpp>
#include <boost/python/return_by_value.hpp>
#include <boost/python/return_value_policy.hpp>

// classes to wrap
struct Bar { };

Bar global_bar;

// functions to wrap:
Bar b1();
Bar& b2();
Bar const& b3();

// Wrapper code
using namespace boost::python;
template <class R>
void def_void_function(char const* name, R (*f)())
   def(name, f, return_value_policy<return_by_value>());

    def_void_function("b1", b1);
    def_void_function("b2", b2);
    def_void_function("b3", b3);

Python Code

>>> from my_module import *
>>> b = b1() # each of these calls
>>> b = b2() # creates a brand
>>> b = b3() # new Bar object

Revised 13 November, 2002

© Copyright Dave Abrahams 2002.