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| <title>Boost.Python - <boost/python/data_members.hpp></title> |
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| <td valign="top"> |
| <h1 align="center"><a href="../index.html">Boost.Python</a></h1> |
| |
| <h2 align="center">Header |
| <boost/python/data_members.hpp></h2> |
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| </tr> |
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| <hr> |
| |
| <h2>Contents</h2> |
| |
| <dl class="page-index"> |
| <dt><a href="#introduction">Introduction</a></dt> |
| |
| <dt><a href="#functions">Functions</a></dt> |
| |
| <dd> |
| <dl class="page-index"> |
| <dt><a href="#make_getter-spec">make_getter</a></dt> |
| |
| <dt><a href="#make_setter-spec">make_setter</a></dt> |
| </dl> |
| </dd> |
| |
| <dt><a href="#examples">Example</a></dt> |
| </dl> |
| <hr> |
| |
| <h2><a name="introduction"></a>Introduction</h2> |
| |
| <p><code><a href="#make_getter-spec">make_getter</a>()</code> and |
| <code><a href="#make_setter-spec">make_setter</a>()</code> are the |
| functions used internally by <code>class_<>::<a href= |
| "class.html#class_-spec-modifiers">def_readonly</a></code> and |
| <code>class_<>::<a href= |
| "class.html#class_-spec-modifiers">def_readwrite</a></code> to produce |
| Python callable objects which wrap C++ data members.</p> |
| |
| <h2><a name="functions"></a>Functions</h2> |
| <pre> |
| <a name="make_getter-spec">template <class C, class D></a> |
| <a href="object.html#object-spec">object</a> make_getter(D C::*pm); |
| |
| template <class C, class D, class Policies> |
| <a href= |
| "object.html#object-spec">object</a> make_getter(D C::*pm, Policies const& policies); |
| </pre> |
| |
| <dl class="function-semantics"> |
| <dt><b>Requires:</b> <code>Policies</code> is a model of <a href= |
| "CallPolicies.html">CallPolicies</a>.</dt> |
| |
| <dt><b>Effects:</b> Creates a Python callable object which accepts a |
| single argument that can be converted <code>from_python</code> to |
| <code>C*</code>, and returns the corresponding member <code>D</code> |
| member of the <code>C</code> object, converted <code>to_python</code>. |
| If <code>policies</code> is supplied, it will be applied to the |
| function as described <a href="CallPolicies.html">here</a>. Otherwise, |
| the library attempts to determine whether <code>D</code> is a |
| user-defined class type, and if so uses <code><a href= |
| "return_internal_reference.html#return_internal_reference-spec">return_internal_reference</a><></code></dt> |
| |
| <dt>for <code>Policies</code>. Note that this test may inappropriately |
| choose <code>return_internal_reference<></code> in some cases |
| when <code>D</code> is a smart pointer type. This is a known |
| defect.</dt> |
| |
| <dt><b>Returns:</b> An instance of <a href= |
| "object.html#object-spec">object</a> which holds the new Python |
| callable object.</dt> |
| </dl> |
| <pre> |
| template <class D> |
| <a href="object.html#object-spec">object</a> make_getter(D const& d); |
| template <class D, class Policies> |
| <a href= |
| "object.html#object-spec">object</a> make_getter(D const& d, Policies const& policies); |
| |
| template <class D> |
| <a href="object.html#object-spec">object</a> make_getter(D const* p); |
| template <class D, class Policies> |
| <a href= |
| "object.html#object-spec">object</a> make_getter(D const* p, Policies const& policies); |
| </pre> |
| |
| <dl class="function-semantics"> |
| <dt><b>Requires:</b> <code>Policies</code> is a model of <a href= |
| "CallPolicies.html">CallPolicies</a>.</dt> |
| |
| <dt><b>Effects:</b> Creates a Python callable object which accepts no |
| arguments and returns <code>d</code> or <code>*p</code>, converted |
| <code>to_python</code> on demand. If <code>policies</code> is supplied, |
| it will be applied to the function as described <a href= |
| "CallPolicies.html">here</a>. Otherwise, the library attempts to |
| determine whether <code>D</code> is a user-defined class type, and if |
| so uses <code><a href= |
| "reference_existing_object.html#reference_existing_object-spec">reference_existing_object</a></code></dt> |
| |
| <dt>for <code>Policies</code>.</dt> |
| |
| <dt><b>Returns:</b> An instance of <a href= |
| "object.html#object-spec">object</a> which holds the new Python |
| callable object.</dt> |
| </dl> |
| <pre> |
| <a name="make_setter-spec">template <class C, class D></a> |
| <a href="object.html#object-spec">object</a> make_setter(D C::*pm); |
| |
| template <class C, class D, class Policies> |
| <a href= |
| "object.html#object-spec">object</a> make_setter(D C::*pm, Policies const& policies); |
| </pre> |
| |
| <dl class="function*-semantics"> |
| <dt><b>Requires:</b> <code>Policies</code> is a model of <a href= |
| "CallPolicies.html">CallPolicies</a>.</dt> |
| |
| <dt><b>Effects:</b> Creates a Python callable object which, when called |
| from Python, expects two arguments which can be converted |
| <code>from_python</code> to <code>C*</code> and |
| <code>D const&</code>, respectively, and sets the |
| corresponding <code>D</code> member of the <code>C</code> object. If |
| <code>policies</code> is supplied, it will be applied to the function |
| as described <a href="CallPolicies.html">here</a>.</dt> |
| |
| <dt><b>Returns:</b> An instance of <a href= |
| "object.html#object-spec">object</a> which holds the new Python |
| callable object.</dt> |
| </dl> |
| <pre> |
| template <class D> |
| <a href="object.html#object-spec">object</a> make_setter(D& d); |
| template <class D, class Policies> |
| <a href= |
| "object.html#object-spec">object</a> make_setter(D& d, Policies const& policies); |
| |
| template <class D> |
| <a href="object.html#object-spec">object</a> make_setter(D* p); |
| template <class D, class Policies> |
| <a href= |
| "object.html#object-spec">object</a> make_setter(D* p, Policies const& policies); |
| </pre> |
| |
| <dl class="function-semantics"> |
| <dt><b>Requires:</b> <code>Policies</code> is a model of <a href= |
| "CallPolicies.html">CallPolicies</a>.</dt> |
| |
| <dt><b>Effects:</b> Creates a Python callable object which accepts one |
| argument, which is converted from Python to <code>D const&</code> |
| and written into <code>d</code> or <code>*p</code>, respectively. If |
| <code>policies</code> is supplied, it will be applied to the function |
| as described <a href="CallPolicies.html">here</a>.</dt> |
| |
| <dt><b>Returns:</b> An instance of <a href= |
| "object.html#object-spec">object</a> which holds the new Python |
| callable object.</dt> |
| </dl> |
| |
| <h2><a name="examples"></a>Example</h2> |
| |
| <p>The code below uses make_getter and make_setter to expose a data |
| member as functions:</p> |
| <pre> |
| #include <boost/python/data_members.hpp> |
| #include <boost/python/module.hpp> |
| #include <boost/python/class.hpp> |
| |
| struct X |
| { |
| X(int x) : y(x) {} |
| int y; |
| }; |
| |
| using namespace boost::python; |
| |
| BOOST_PYTHON_MODULE_INIT(data_members_example) |
| { |
| class_<X>("X", init<int>()) |
| .def("get", make_getter(&X::y)) |
| .def("set", make_setter(&X::y)) |
| ; |
| } |
| </pre> |
| It can be used this way in Python: |
| <pre> |
| >>> from data_members_example import * |
| >>> x = X(1) |
| >>> x.get() |
| 1 |
| >>> x.set(2) |
| >>> x.get() |
| 2 |
| </pre> |
| |
| <p> |
| <!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B, %Y" startspan --> |
| 5 August, 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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