boost-react-native-bundle

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">    <html> <head> <meta name="generator" content= "HTML Tidy for Windows (vers 1st August 2002), see www.w3.org"> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <link rel="stylesheet" type="text/css" href="../boost.css"> <title>Boost.Python - <boost/python/init.hpp></title> </head> <body link="#0000ff" vlink="#800080"> <table border="0" cellpadding="7" cellspacing="0" width="100%" summary= "header"> <tr> <td valign="top" width="300"> <h3><a href="../../../../index.htm"><img height="86" width="277" alt="C++ Boost" src="../../../../boost.png" border="0"></a></h3> </td> <td valign="top"> <h1 align="center"><a href="../index.html">Boost.Python</a></h1> <h2 align="center">Headers <boost/python/init.hpp></h2> </td> </tr> </table> <hr> <h2>Contents</h2> <dl class="page-index"> <dt><a href="#introduction">Introduction</a></dt> <dt><a href= "#init-expressions"><em>init-expressions</em></a></dt> <dt><a href="#classes">Classes</a></dt> <dd> <dl class="page-index"> <dt><a href="#init-spec">Class template <code>init</code></a></dt> <dd> <dl class="page-index"> <dt><a href="#init-spec-synopsis">Class template <code>init</code> synopsis</a></dt> <dt><a href="#init-spec-ctors">Class <code>init</code> constructors</a></dt> </dl> </dd> <dt><a href="#optional-spec">Class template <code>optional</code></a></dt> <dd> <dl class="page-index"> <dt><a href="#optional-spec-synopsis">Class template <code>optional</code> synopsis</a></dt> </dl> </dd> </dl> </dd> <dt><a href="#examples">Example(s)</a></dt> </dl> <hr> <h2><a name="introduction"></a>Introduction</h2> <p><code><boost/python/init.hpp></code> defines the interface for exposing C++ constructors to Python as extension class <code>__init__</code> functions.</p> <h2><a name="init-expressions"><em>init-expressions</em></a></h2> An <em>init-expression</em> is used to describe a family of <code>__init__</code> methods to be generated for an extension class, and the result 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 method's <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 <code>__init__</code> function(s).</dt> <dt><b>call policies:</b> An instance of a model of <a href= "CallPolicies.html">CallPolicies</a>.</dt> <dt><b>argument types:</b> An MPL sequence of C++ argument types which will be used to construct the wrapped C++ object. An init expression has one or more <b>valid prefixes</b> which are given by a sequence of prefixes of its argument types.</dt> </dl> </blockquote> <h2><a name="classes"></a>Classes</h2> <h3><a name="init-spec"></a>Class template <code>init<T1 =</code> <i>unspecified</i><code>, T2 =</code> <i>unspecified</i><code>,</code>...<code>Tn</code> = <i>unspecified</i><code>></code></h3> <p>A <a href="../../../mpl/doc/refmanual/forward-sequence.html">MPL sequence</a> which can be used to specify a family of one or more <code>__init__</code> functions. Only the last <code>T</code><i><small>i</small></i> supplied may be an instantiation of <a href= "#optional-spec"><code>optional</code></a><code><</code>...<code>></code>.</p> <h4><a name="init-spec-synopsis"></a>Class template <code>init</code> synopsis</h4> <pre> namespace boost { namespace python { template <T1 = <i>unspecified</i>,...T<i>n</i> = <i>unspecified</i>> struct init { init(char const* doc = 0); template <class Keywords> init(Keywords const& kw, char const* doc = 0); template <class Keywords> init(char const* doc, Keywords const& kw); template <class CallPolicies> <em>unspecified</em> operator[](CallPolicies const& policies) const }; }} </pre> <h4><a name="init-spec-ctors"></a>Class template <code>init</code> constructors</h4> <pre> init(char const* doc = 0); template <class Keywords> init(Keywords const& kw, char const* doc = 0); template <class Keywords> init(char const* doc, Keywords const& kw); </pre> <dl class="function-semantics"> <dt><b>Requires:</b> If supplied, <code>doc</code> is an <a href= "definitions.html#ntbs">ntbs</a>. If supplied, <code>kw</code> is the result of a <a href="args.html#keyword-expression"></a></dt> <dt><b>Effects:</b> The result is an <em>init-expression</em> whose <em>docstring</em> is <code>doc</code> and whose <em>keywords</em> are a reference to <code>kw</code>. If the first form is used, the resulting expression's <em>keywords</em> are empty. The expression's <em>call policies</em> are an instance of <a href= "default_call_policies.html#default_call_policies-spec">default_call_policies</a>. If <code>T</code><i><small>n</small></i> is <a href= "#optional-spec"><code>optional</code></a><code><U1, U2,</code>... <code>U</code><small><i>m</i></small><code>></code>, the expression's <em>valid prefixes</em> are given by:</dt> <dd> <blockquote> (<code>T1, T2,</code>...<code>T</code><i><small>n-1</small></i>), (<code>T1, T2,</code>...<code>T</code><i><small>n-1</small></i> <code>, U1</code>), (<code>T1, T2,</code>...<code>T</code><i><small>n-1</small></i> <code>, U1, U2</code>), ...(<code>T1, T2,</code>...<code>T</code><i><small>n-1</small></i> <code>, U1, U2,</code>...<code>U</code><i><small>m</small></i>). </blockquote> Otherwise, the expression has one <em>valid prefix</em> given by the the template arguments the user specified. </dd> </dl> <h4><a name="init-spec-observers"></a>Class template <code>init</code> observer functions</h4> <pre> template <class Policies> <em>unspecified</em> operator[](Policies const& policies) const </pre> <dl class="function-semantics"> <dt><b>Requires:</b> Policies is a model of <a href= "CallPolicies.html">CallPolicies</a>.</dt> <dt><b>Effects:</b> Returns a new <a href= "#init-expressions"><em>init-expression</em></a> with all the same properties as the <code>init</code> object except that its <em>call policies</em> are replaced by a reference to <code>policies</code>.</dt> </dl> <h3><a name="optional-spec"></a>Class template <code>optional<T1 =</code> <i>unspecified</i><code>, T2 =</code> <i>unspecified</i><code>,</code>...<code>Tn</code> = <i>unspecified</i><code>></code></h3> <p>A <a href="../../../mpl/doc/refmanual/forward-sequence.html">MPL sequence</a> which can be used to specify the optional arguments to an <code>__init__</code> function.</p> <h4><a name="optional-spec-synopsis"></a>Class template <code>optional</code> synopsis</h4> <pre> namespace boost { namespace python { template <T1 = <i>unspecified</i>,...T<i>n</i> = <i>unspecified</i>> struct optional {}; }} </pre> <h2><a name="examples"></a>Example(s)</h2> <p>Given the C++ declarations:</p> <pre> class Y; class X { public: X(int x, Y* y) : m_y(y) {} X(double); private: Y* m_y; }; </pre> A corresponding Boost.Python extension class can be created with: <pre> using namespace boost::python; class_<X>("X", "This is X's docstring.", init<int,char const*>(args("x","y"), "X.__init__'s docstring")[ with_custodian_and_ward<1,3>()] ) .def(init<double>()) ; </pre> <hr> Revised  13 November, 2002  <p><i>© Copyright <a href= "http://www.boost.org/people/dave_abrahams.htm">Dave Abrahams</a> 2002.</i></p> </body> </html>