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/handle.hpp></title> <style type="text/css"> p.c4 {font-style: italic} span.c3 {color: #ff0000} h2.c2 {text-align: center} h1.c1 {text-align: center} </style> </head> <body> <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 class="c1"><a href="../index.html">Boost.Python</a></h1> <h2 class="c2">Header <boost/python/handle.hpp></h2> </td> </tr> </table> <hr> <h2>Contents</h2> <dl class="page-index"> <dt><a href="#introduction">Introduction</a></dt> <dt><a href="#classes">Classes</a></dt> <dd> <dl class="page-index"> <dt><a href="#handle-spec">Class template <code>handle</code></a></dt> <dd> <dl class="page-index"> <dt><a href="#handle-spec-synopsis">Class <code>handle</code> synopsis</a></dt> <dt><a href="#handle-spec-ctors">Class <code>handle</code> constructors and destructor</a></dt> <dt><a href="#handle-spec-modifiers">Class <code>handle</code> modifier functions</a></dt> <dt><a href="#handle-spec-observers">Class <code>handle</code> observer functions</a></dt> </dl> </dd> </dl> </dd> <dt><a href="#functions">Functions</a></dt> <dd> <dl class="page-index"> <dt><a href="#borrowed-spec"><code>borrowed</code></a></dt> <dt><a href="#allow_null-spec"><code>allow_null</code></a></dt> </dl> </dd> </dl> <hr> <h2><a name="introduction"></a>Introduction</h2> <p><code><boost/python/handle.hpp></code> provides <code>class template handle</code>, a smart pointer for managing reference-counted Python objects.</p> <h2><a name="classes"></a>Classes</h2> <h3><a name="handle-spec"></a>Class template <code>handle</code></h3> <p><code>handle</code> is a smart pointer to a Python object type; it holds a pointer of type <code>T*</code>, where T is its template parameter. <code>T</code> must be either a type derived from <code>PyObject</code> or a <a href="definitions.html#POD">POD</a> type whose initial <code>sizeof(PyObject)</code> bytes are layout-compatible with <code>PyObject</code>. Use <code>handle<></code> at the boundary between the Python/'C' API and high-level code; prefer <code><a href="object.html#object-spec">object</a></code> for a generalized interface to Python objects.</p> <p><a name="upcast"></a>In this document, the term "upcast" refers to an operation which converts a pointer <code>Y*</code> to a base class pointer <code>T*</code> via <code>static_cast<T*></code> if <code>Y</code> is derived from <code>T</code>, or via C-style cast <code>(T*)</code> if it is not. However, in the latter case the "upcast" is ill-formed if the initial <code>sizeof(PyObject)</code> bytes of <code>Y</code> are not layout-compatible with <code>PyObject</code>.</p> <h4><a name="handle-spec-synopsis"></a>Class template handle synopsis</h4> <pre> namespace boost { namespace python { template <class T> class handle { typedef <i>unspecified-member-function-pointer</i> bool_type; public: // types typedef T element_type; public: // member functions ~handle(); template <class Y> explicit handle(detail::borrowed<null_ok<Y> >* p); template <class Y> explicit handle(null_ok<detail::borrowed<Y> >* p); template <class Y> explicit handle(detail::borrowed<Y>* p); template <class Y> explicit handle(null_ok<Y>* p); template <class Y> explicit handle(Y* p); handle(); handle& operator=(handle const& r); template<typename Y> handle& operator=(handle<Y> const & r); // never throws template <typename Y> handle(handle<Y> const& r); handle(handle const& r); T* operator-> () const; T& operator* () const; T* get() const; void reset(); T* release(); operator bool_type() const; // never throws private: T* m_p; }; template <class T> struct null_ok; namespace detail { template <class T> struct borrowed; } }} </pre> <h4><a name="handle-spec-ctors">Class <code>handle</code> constructors and destructor</a></h4> <pre> virtual ~handle(); </pre> <dl class="function-semantics"> <dt><b>Effects:</b> <code>Py_XDECREF(</code><i>upcast</i><code><PyObject*>(m_p))</code></dt> </dl> <pre> template <class Y> explicit handle(detail::borrowed<null_ok<Y> >* p); </pre> <dl class="function-semantics"> <dt><b>Effects:</b> <code>Py_XINCREF(</code><i>upcast</i><code><PyObject*>(p)); m_p = </code><i>upcast</i><code><T*>(p);</code></dt> </dl> <pre> template <class Y> explicit handle(null_ok<detail::borrowed<Y> >* p); </pre> <dl class="function-semantics"> <dt><b>Effects:</b> <code>Py_XINCREF(</code><i>upcast</i><code><PyObject*>(p)); m_p = </code><i>upcast</i><code><T*>(p);</code></dt> </dl> <pre> template <class Y> explicit handle(detail::borrowed<Y>* p); </pre> <dl class="function-semantics"> <dt><b>Effects:</b> <code>Py_XINCREF(</code><i>upcast</i><code><PyObject*>(p)); m_p = </code><i>upcast</i><code><T*>(<a href= "errors.html#expect_non_null-spec">expect_non_null</a>(p));</code></dt> </dl> <pre> template <class Y> explicit handle(null_ok<Y>* p); </pre> <dl class="function-semantics"> <dt><b>Effects:</b> <code>m_p = </code><i>upcast</i><code><T*>(p);</code></dt> </dl> <pre> template <class Y> explicit handle(Y* p); </pre> <dl class="function-semantics"> <dt><b>Effects:</b> <code>m_p = </code><i>upcast</i><code><T*>(<a href= "errors.html#expect_non_null-spec">expect_non_null</a>(p));</code></dt> </dl> <pre> handle(); </pre> <dl class="function-semantics"> <dt><b>Effects:</b> <code>m_p = 0;</code></dt> </dl> <pre> template <typename Y> handle(handle<Y> const& r); handle(handle const& r); </pre> <dl class="function-semantics"> <dt><b>Effects:</b> <code>m_p = r.m_p; Py_XINCREF(</code><i>upcast</i><code><PyObject*>(m_p));</code></dt> </dl> <h4><a name="handle-spec-modifiers">Class <code>handle</code> modifiers</a></h4> <pre> handle& operator=(handle const& r); template<typename Y> handle& operator=(handle<Y> const & r); // never throws </pre> <dl class="function-semantics"> <dt><b>Effects:</b> <code>Py_XINCREF(</code><i>upcast</i><code><PyObject*>(r.m_p)); Py_XDECREF(</code><i> upcast</i><code><PyObject*>(m_p)); m_p = r.m_p;</code></dt> </dl> <pre> T* release(); </pre> <dl class="function-semantics"> <dt><b>Effects:</b> <code>T* x = m_p; m_p = 0;return x;</code></dt> </dl> <pre> void reset(); </pre> <dl class="function-semantics"> <dt><b>Effects:</b> <code>*this = handle<T>();</code></dt> </dl> <h4><a name="handle-spec-observers">Class <code>handle</code> observers</a></h4> <pre> T* operator-> () const; T* get() const; </pre> <dl class="function-semantics"> <dt><b>Returns:</b> <code>m_p;</code></dt> </dl> <pre> T& operator* () const; </pre> <dl class="function-semantics"> <dt><b>Returns:</b> <code>*m_p;</code></dt> </dl> <pre> operator bool_type() const; // never throws </pre> <dl class="function-semantics"> <dt><b>Returns:</b> 0 if <code>m_p == 0</code>, a pointer convertible to <code>true</code> otherwise.</dt> </dl> <h2><a name="functions"></a>Functions</h2> <h3><a name="borrowed-spec"></a><code>borrowed</code></h3> <pre> template <class T> detail::borrowed<T>* borrowed(T* p) { return (detail::borrowed<T>*)p; } </pre> <h3><a name="allow_null-spec"></a><code>allow_null</code></h3> <pre> template <class T> null_ok<T>* allow_null(T* p) { return (null_ok<T>*)p; } </pre> <p>Revised  13 November, 2002  </p> <p class="c4">© Copyright <a href= "http://www.boost.org/people/dave_abrahams.htm">Dave Abrahams</a> 2002 .</p> </body> </html>