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| 3 | <!-- Copyright David Abrahams 2006. Distributed under the Boost --> |
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| 4 | <!-- Software License, Version 1.0. (See accompanying --> |
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| 12 | |
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| 13 | <title>Boost.Python - <boost/python/overloads.hpp></title> |
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| 14 | </head> |
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| 15 | |
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| 16 | <body> |
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| 17 | <table border="0" cellpadding="7" cellspacing="0" width="100%" summary= |
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| 18 | "header"> |
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| 19 | <tr> |
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| 20 | <td valign="top" width="300"> |
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| 21 | <h3><a href="../../../../index.htm"><img height="86" width="277" |
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| 22 | alt="C++ Boost" src="../../../../boost.png" border="0"></a></h3> |
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| 23 | </td> |
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| 24 | |
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| 25 | <td valign="top"> |
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| 26 | <h1 align="center"><a href="../index.html">Boost.Python</a></h1> |
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| 27 | |
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| 28 | <h2 align="center">Header <boost/python/overloads.hpp></h2> |
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| 29 | </td> |
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| 30 | </tr> |
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| 31 | </table> |
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| 32 | <hr> |
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| 33 | |
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| 34 | <h2>Contents</h2> |
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| 35 | |
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| 36 | <dl class="page-index"> |
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| 37 | <dt><a href="#introduction">Introduction</a></dt> |
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| 38 | |
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| 39 | <dt><a href= |
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| 40 | "#overload-dispatch-expression"><i>overload-dispatch-expressions</i></a></dt> |
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| 41 | |
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| 42 | <dt><a href= "#OverloadDispatcher-concept">OverloadDispatcher</a> concept</dt> |
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| 43 | |
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| 44 | <dt><a href="#macros">Macros</a></dt> |
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| 45 | |
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| 46 | <dd> |
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| 47 | <dl class="page-index"> |
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| 48 | <dt><a href= |
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| 49 | "#BOOST_PYTHON_FUNCTION_OVERLOADS-spec">BOOST_PYTHON_FUNCTION_OVERLOADS</a></dt> |
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| 50 | |
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| 51 | <dt><a href= |
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| 52 | "#BOOST_PYTHON_MEMBER_FUNCTION_OVERLOADS-spec">BOOST_PYTHON_MEMBER_FUNCTION_OVERLOADS</a></dt> |
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| 53 | </dl> |
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| 54 | </dd> |
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| 55 | |
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| 56 | <dt><a href="#examples">Example(s)</a></dt> |
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| 57 | </dl> |
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| 58 | <hr> |
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| 59 | |
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| 60 | <h2><a name="introduction"></a>Introduction</h2> |
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| 61 | |
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| 62 | <p>Defines facilities for generating families of overloaded Python |
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| 63 | functions and extension class methods from C++ functions and |
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| 64 | member functions with default arguments, or from similar families |
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| 65 | of C++ overloads</p> |
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| 66 | |
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| 67 | <h2><a name= |
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| 68 | "overload-dispatch-expression"></a><i>overload-dispatch-expressions</i></h2> |
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| 69 | |
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| 70 | <p> |
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| 71 | An <em>overload-dispatch-expression</em> is used to describe a |
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| 72 | family of overloaded methods to be generated for an extension |
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| 73 | class. It has the following properties: |
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| 74 | |
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| 75 | <blockquote> |
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| 76 | <dl class="properties"> |
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| 77 | <dt><b>docstring:</b> An <a href="definitions.html#ntbs">ntbs</a> |
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| 78 | whose value will bound to the methods' <code>__doc__</code> |
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| 79 | attribute</dt> |
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| 80 | |
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| 81 | <dt><b>keywords:</b> A <a href= |
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| 82 | "args.html#keyword-expression">keyword-expression</a> which |
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| 83 | will be used to name (a trailing subsequence of) the arguments |
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| 84 | to the generated methods.</dt> |
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| 85 | |
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| 86 | <dt><b>call policies:</b> An instance of some type which models <a href= |
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| 87 | "CallPolicies.html">CallPolicies</a>.</dt> |
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| 88 | |
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| 89 | <dt><b>minimum <a href="definitions.html#arity">arity</a></b> |
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| 90 | The minimum number of arguments to be accepted by a generated |
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| 91 | method overload.</dt> |
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| 92 | |
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| 93 | <dt><b>maximum <a href="definitions.html#arity">arity</a></b> |
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| 94 | The maximum number of arguments to be accepted by a generated |
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| 95 | method overload.</dt> |
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| 96 | </dl> |
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| 97 | </blockquote> |
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| 98 | |
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| 99 | <h2><a name="OverloadDispatcher-concept"></a>OverloadDispatcher Concept</h2> |
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| 100 | |
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| 101 | An OverloadDispatcher <code>X</code> is a class which has a |
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| 102 | <em>minimum arity</em> and a <em>maximum arity</em>, and for which |
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| 103 | the following following are valid <a |
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| 104 | href="#overload-dispatch-expression"><em>overload-dispatch-expression</em></a>s, |
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| 105 | with the same minimum and maximum arity as the OverloadDispatcher. |
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| 106 | |
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| 107 | <pre> |
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| 108 | X() |
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| 109 | X(docstring) |
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| 110 | X(docstring, keywords) |
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| 111 | X(keywords, docstring) |
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| 112 | X()[policies] |
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| 113 | X(docstring)[policies] |
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| 114 | X(docstring, keywords)[policies] |
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| 115 | X(keywords, docstring)[policies] |
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| 116 | </pre> |
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| 117 | |
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| 118 | <ul> |
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| 119 | <li>If <code>policies</code> are supplied, it must be an instance of a |
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| 120 | type which models <a |
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| 121 | href="CallPolicies.html#CallPolicies-concept">CallPolicies</a>, and |
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| 122 | will be used as the result's call policies. Otherwise the result's |
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| 123 | call policies will be an instance of <a |
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| 124 | href="default_call_policies.html#default_call_policies-spec">default_call_policies</a>. |
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| 125 | |
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| 126 | <li>If <code>docstring</code> is supplied it must be an <a |
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| 127 | href="definitions.html#ntbs">ntbs</a>, and will be used as the result's docstring. Otherwise the result has an empty docstring. |
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| 128 | |
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| 129 | <li>If <code>keywords</code> is supplied it must be the result of a <a |
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| 130 | href= "args.html#keyword-expression">keyword-expression</a> |
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| 131 | whose length is no greater than <code>X</code>'s maximum |
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| 132 | arity, and will be used as the result's keywords. Otherwise |
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| 133 | the result's keywords will be empty. |
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| 134 | </ul> |
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| 135 | |
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| 136 | |
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| 137 | |
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| 138 | |
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| 139 | <h2><a name="macros"></a>Macros</h2> |
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| 140 | |
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| 141 | <h3><a name= |
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| 142 | "BOOST_PYTHON_FUNCTION_OVERLOADS-spec">BOOST_PYTHON_FUNCTION_OVERLOADS(name, func_id, min_args, max_args)</a></h3> |
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| 143 | Expands to the definition of an OverloadDispatcher called |
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| 144 | <code>name</code> in the current scope which can be used to |
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| 145 | generate the following function invocation: |
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| 146 | <pre> |
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| 147 | func_id(a<small><i>1</i></small>, a<small><i>2</i></small>,...a<small><i>i</i></small>); |
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| 148 | </pre> |
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| 149 | |
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| 150 | for all <code>min_args</code> <= <i>i</i> <= <code>max_args</code>. |
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| 151 | |
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| 152 | <h3><a name= |
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| 153 | "BOOST_PYTHON_MEMBER_FUNCTION_OVERLOADS-spec">BOOST_PYTHON_MEMBER_FUNCTION_OVERLOADS(name, member_name, min_args, max_args)</a></h3> |
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| 154 | |
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| 155 | Expands to the definition of an OverloadDispatcher called |
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| 156 | <code>name</code> in the current scope which can be used to |
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| 157 | generate the following function invocation: |
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| 158 | <pre> |
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| 159 | x.member_name(a<small><i>1</i></small>, a<small><i>2</i></small>,...a<small><i>i</i></small>); |
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| 160 | </pre> |
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| 161 | |
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| 162 | for all <code>min_args</code> <= <i>i</i> <= |
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| 163 | <code>max_args</code>, where <code>x</code> is a reference to an |
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| 164 | object of class type. |
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| 165 | |
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| 166 | <h2><a name="examples"></a>Example(s)</h2> |
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| 167 | |
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| 168 | <pre> |
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| 169 | #include <boost/python/module.hpp> |
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| 170 | #include <boost/python/def.hpp> |
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| 171 | #include <boost/python/args.hpp> |
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| 172 | #include <boost/python/tuple.hpp> |
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| 173 | #include <boost/python/class.hpp> |
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| 174 | #include <boost/python/overloads.hpp> |
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| 175 | #include <boost/python/return_internal_reference.hpp> |
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| 176 | |
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| 177 | using namespace boost::python; |
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| 178 | |
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| 179 | tuple f(int x = 1, double y = 4.25, char const* z = "wow") |
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| 180 | { |
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| 181 | return make_tuple(x, y, z); |
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| 182 | } |
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| 183 | |
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| 184 | BOOST_PYTHON_FUNCTION_OVERLOADS(f_overloads, f, 0, 3) |
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| 185 | |
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| 186 | struct Y {}; |
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| 187 | struct X |
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| 188 | { |
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| 189 | Y& f(int x, double y = 4.25, char const* z = "wow") |
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| 190 | { |
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| 191 | return inner; |
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| 192 | } |
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| 193 | Y inner; |
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| 194 | }; |
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| 195 | |
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| 196 | BOOST_PYTHON_MEMBER_FUNCTION_OVERLOADS(f_member_overloads, f, 1, 3) |
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| 197 | |
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| 198 | BOOST_PYTHON_MODULE(args_ext) |
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| 199 | { |
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| 200 | def("f", f, |
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| 201 | f_overloads( |
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| 202 | args("x", "y", "z"), "This is f's docstring" |
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| 203 | )); |
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| 204 | |
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| 205 | |
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| 206 | class_<Y>("Y") |
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| 207 | ; |
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| 208 | |
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| 209 | class_<X>("X", "This is X's docstring") |
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| 210 | .def("f1", &X::f, |
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| 211 | f_member_overloads( |
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| 212 | args("x", "y", "z"), "f's docstring" |
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| 213 | )[return_internal_reference<>()] |
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| 214 | ) |
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| 215 | ; |
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| 216 | } |
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| 217 | </pre> |
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| 218 | |
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| 219 | <p>Revised |
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| 220 | <!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B, %Y" startspan --> |
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| 221 | 15 April, 2003 |
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| 222 | <!--webbot bot="Timestamp" endspan i-checksum="39359" --> |
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| 223 | </p> |
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| 224 | |
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| 225 | <p><i>© Copyright <a href= |
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| 226 | "../../../../people/dave_abrahams.htm">Dave Abrahams</a> 2002.</i></p> |
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| 227 | </body> |
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| 228 | </html> |
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| 229 | |
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