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| <h1 align="center"><a href="../index.html">Boost.Python</a></h1> |
| |
| <h2 align="center">Header <boost/python/overloads.hpp></h2> |
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| <hr> |
| |
| <h2>Contents</h2> |
| |
| <dl class="page-index"> |
| <dt><a href="#introduction">Introduction</a></dt> |
| |
| <dt><a href= |
| "#overload-dispatch-expression"><i>overload-dispatch-expressions</i></a></dt> |
| |
| <dt><a href= "#OverloadDispatcher-concept">OverloadDispatcher</a> concept</dt> |
| |
| <dt><a href="#macros">Macros</a></dt> |
| |
| <dd> |
| <dl class="page-index"> |
| <dt><a href= |
| "#BOOST_PYTHON_FUNCTION_OVERLOADS-spec">BOOST_PYTHON_FUNCTION_OVERLOADS</a></dt> |
| |
| <dt><a href= |
| "#BOOST_PYTHON_MEMBER_FUNCTION_OVERLOADS-spec">BOOST_PYTHON_MEMBER_FUNCTION_OVERLOADS</a></dt> |
| </dl> |
| </dd> |
| |
| <dt><a href="#examples">Example(s)</a></dt> |
| </dl> |
| <hr> |
| |
| <h2><a name="introduction"></a>Introduction</h2> |
| |
| <p>Defines facilities for generating families of overloaded Python |
| functions and extension class methods from C++ functions and |
| member functions with default arguments, or from similar families |
| of C++ overloads</p> |
| |
| <h2><a name= |
| "overload-dispatch-expression"></a><i>overload-dispatch-expressions</i></h2> |
| |
| <p> |
| An <em>overload-dispatch-expression</em> is used to describe a |
| family of overloaded methods to be generated for an extension |
| class. It has the following properties: |
| |
| <blockquote> |
| <dl class="properties"> |
| <dt><b>docstring:</b> An <a href="definitions.html#ntbs">ntbs</a> |
| whose value will bound to the methods' <code>__doc__</code> |
| attribute</dt> |
| |
| <dt><b>keywords:</b> A <a href= |
| "args.html#keyword-expression">keyword-expression</a> which |
| will be used to name (a trailing subsequence of) the arguments |
| to the generated methods.</dt> |
| |
| <dt><b>call policies:</b> An instance of some type which models <a href= |
| "CallPolicies.html">CallPolicies</a>.</dt> |
| |
| <dt><b>minimum <a href="definitions.html#arity">arity</a></b> |
| The minimum number of arguments to be accepted by a generated |
| method overload.</dt> |
| |
| <dt><b>maximum <a href="definitions.html#arity">arity</a></b> |
| The maximum number of arguments to be accepted by a generated |
| method overload.</dt> |
| </dl> |
| </blockquote> |
| |
| <h2><a name="OverloadDispatcher-concept"></a>OverloadDispatcher Concept</h2> |
| |
| An OverloadDispatcher <code>X</code> is a class which has a |
| <em>minimum arity</em> and a <em>maximum arity</em>, and for which |
| the following following are valid <a |
| href="#overload-dispatch-expression"><em>overload-dispatch-expression</em></a>s, |
| with the same minimum and maximum arity as the OverloadDispatcher. |
| |
| <pre> |
| X() |
| X(docstring) |
| X(docstring, keywords) |
| X(keywords, docstring) |
| X()[policies] |
| X(docstring)[policies] |
| X(docstring, keywords)[policies] |
| X(keywords, docstring)[policies] |
| </pre> |
| |
| <ul> |
| <li>If <code>policies</code> are supplied, it must be an instance of a |
| type which models <a |
| href="CallPolicies.html#CallPolicies-concept">CallPolicies</a>, and |
| will be used as the result's call policies. Otherwise the result's |
| call policies will be an instance of <a |
| href="default_call_policies.html#default_call_policies-spec">default_call_policies</a>. |
| |
| <li>If <code>docstring</code> is supplied it must be an <a |
| href="definitions.html#ntbs">ntbs</a>, and will be used as the result's docstring. Otherwise the result has an empty docstring. |
| |
| <li>If <code>keywords</code> is supplied it must be the result of a <a |
| href= "args.html#keyword-expression">keyword-expression</a> |
| whose length is no greater than <code>X</code>'s maximum |
| arity, and will be used as the result's keywords. Otherwise |
| the result's keywords will be empty. |
| </ul> |
| |
| |
| |
| |
| <h2><a name="macros"></a>Macros</h2> |
| |
| <h3><a name= |
| "BOOST_PYTHON_FUNCTION_OVERLOADS-spec">BOOST_PYTHON_FUNCTION_OVERLOADS(name, func_id, min_args, max_args)</a></h3> |
| Expands to the definition of an OverloadDispatcher called |
| <code>name</code> in the current scope which can be used to |
| generate the following function invocation: |
| <pre> |
| func_id(a<small><i>1</i></small>, a<small><i>2</i></small>,...a<small><i>i</i></small>); |
| </pre> |
| |
| for all <code>min_args</code> <= <i>i</i> <= <code>max_args</code>. |
| |
| <h3><a name= |
| "BOOST_PYTHON_MEMBER_FUNCTION_OVERLOADS-spec">BOOST_PYTHON_MEMBER_FUNCTION_OVERLOADS(name, member_name, min_args, max_args)</a></h3> |
| |
| Expands to the definition of an OverloadDispatcher called |
| <code>name</code> in the current scope which can be used to |
| generate the following function invocation: |
| <pre> |
| x.member_name(a<small><i>1</i></small>, a<small><i>2</i></small>,...a<small><i>i</i></small>); |
| </pre> |
| |
| for all <code>min_args</code> <= <i>i</i> <= |
| <code>max_args</code>, where <code>x</code> is a reference to an |
| object of class type. |
| |
| <h2><a name="examples"></a>Example(s)</h2> |
| |
| <pre> |
| #include <boost/python/module.hpp> |
| #include <boost/python/def.hpp> |
| #include <boost/python/args.hpp> |
| #include <boost/python/tuple.hpp> |
| #include <boost/python/class.hpp> |
| #include <boost/python/overloads.hpp> |
| #include <boost/python/return_internal_reference.hpp> |
| |
| using namespace boost::python; |
| |
| tuple f(int x = 1, double y = 4.25, char const* z = "wow") |
| { |
| return make_tuple(x, y, z); |
| } |
| |
| BOOST_PYTHON_FUNCTION_OVERLOADS(f_overloads, f, 0, 3) |
| |
| struct Y {}; |
| struct X |
| { |
| Y& f(int x, double y = 4.25, char const* z = "wow") |
| { |
| return inner; |
| } |
| Y inner; |
| }; |
| |
| BOOST_PYTHON_MEMBER_FUNCTION_OVERLOADS(f_member_overloads, f, 1, 3) |
| |
| BOOST_PYTHON_MODULE(args_ext) |
| { |
| def("f", f, |
| f_overloads( |
| args("x", "y", "z"), "This is f's docstring" |
| )); |
| |
| |
| class_<Y>("Y") |
| ; |
| |
| class_<X>("X", "This is X's docstring") |
| .def("f1", &X::f, |
| f_member_overloads( |
| args("x", "y", "z"), "f's docstring" |
| )[return_internal_reference<>()] |
| ) |
| ; |
| } |
| </pre> |
| |
| <p>Revised |
| <!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B, %Y" startspan --> |
| 15 April, 2003 |
| <!--webbot bot="Timestamp" endspan i-checksum="39359" --> |
| </p> |
| |
| <p><i>© Copyright <a href= |
| "http://www.boost.org/people/dave_abrahams.htm">Dave Abrahams</a> 2002.</i></p> |
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