| 1 | <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> |
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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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| 5 | <!-- file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) --> |
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| 13 | <title>Boost.Python - <boost/python/handle.hpp></title> |
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| 21 | </head> |
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| 22 | |
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| 23 | <body> |
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| 24 | <table border="0" cellpadding="7" cellspacing="0" width="100%" summary= |
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| 25 | "header"> |
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| 26 | <tr> |
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| 27 | <td valign="top" width="300"> |
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| 28 | <h3><a href="../../../../index.htm"><img height="86" width="277" |
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| 29 | alt="C++ Boost" src="../../../../boost.png" border="0"></a></h3> |
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| 30 | </td> |
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| 31 | |
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| 32 | <td valign="top"> |
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| 33 | <h1 class="c1"><a href="../index.html">Boost.Python</a></h1> |
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| 34 | |
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| 35 | <h2 class="c2">Header <boost/python/handle.hpp></h2> |
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| 36 | </td> |
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| 37 | </tr> |
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| 38 | </table> |
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| 39 | <hr> |
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| 40 | |
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| 41 | <h2>Contents</h2> |
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| 42 | |
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| 43 | <dl class="page-index"> |
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| 44 | <dt><a href="#introduction">Introduction</a></dt> |
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| 45 | |
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| 46 | <dt><a href="#classes">Classes</a></dt> |
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| 47 | |
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| 48 | <dd> |
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| 49 | <dl class="page-index"> |
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| 50 | <dt><a href="#handle-spec">Class template |
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| 51 | <code>handle</code></a></dt> |
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| 52 | |
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| 53 | <dd> |
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| 54 | <dl class="page-index"> |
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| 55 | <dt><a href="#handle-spec-synopsis">Class <code>handle</code> |
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| 56 | synopsis</a></dt> |
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| 57 | |
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| 58 | <dt><a href="#handle-spec-ctors">Class <code>handle</code> |
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| 59 | constructors and destructor</a></dt> |
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| 60 | |
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| 61 | <dt><a href="#handle-spec-modifiers">Class <code>handle</code> |
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| 62 | modifier functions</a></dt> |
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| 63 | |
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| 64 | <dt><a href="#handle-spec-observers">Class <code>handle</code> |
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| 65 | observer functions</a></dt> |
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| 66 | </dl> |
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| 67 | </dd> |
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| 68 | </dl> |
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| 69 | </dd> |
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| 70 | |
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| 71 | <dt><a href="#functions">Functions</a></dt> |
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| 72 | |
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| 73 | <dd> |
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| 74 | <dl class="page-index"> |
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| 75 | <dt><a href="#borrowed-spec"><code>borrowed</code></a></dt> |
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| 76 | |
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| 77 | <dt><a href="#allow_null-spec"><code>allow_null</code></a></dt> |
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| 78 | </dl> |
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| 79 | </dd> |
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| 80 | </dl> |
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| 81 | <hr> |
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| 82 | |
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| 83 | <h2><a name="introduction"></a>Introduction</h2> |
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| 84 | |
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| 85 | <p><code><boost/python/handle.hpp></code> provides |
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| 86 | <code>class template handle</code>, a smart pointer for |
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| 87 | managing reference-counted Python objects.</p> |
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| 88 | |
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| 89 | <h2><a name="classes"></a>Classes</h2> |
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| 90 | |
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| 91 | <h3><a name="handle-spec"></a>Class template <code>handle</code></h3> |
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| 92 | |
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| 93 | <p><code>handle</code> is a smart pointer to a Python object type; it |
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| 94 | holds a pointer of type <code>T*</code>, where T is its template |
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| 95 | parameter. <code>T</code> must be either a type derived from |
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| 96 | <code>PyObject</code> or a <a href="definitions.html#POD">POD</a> type |
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| 97 | whose initial <code>sizeof(PyObject)</code> bytes are layout-compatible |
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| 98 | with <code>PyObject</code>. Use <code>handle<></code> at the |
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| 99 | boundary between the Python/'C' API and high-level code; prefer <code><a |
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| 100 | href="object.html#object-spec">object</a></code> for a generalized |
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| 101 | interface to Python objects.</p> |
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| 102 | |
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| 103 | <p><a name="upcast"></a>In this document, the term "upcast" refers to an |
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| 104 | operation which converts a pointer <code>Y*</code> to a base class |
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| 105 | pointer <code>T*</code> via <code>static_cast<T*></code> if |
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| 106 | <code>Y</code> is derived from <code>T</code>, or via C-style cast |
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| 107 | <code>(T*)</code> if it is not. However, in the latter case the "upcast" |
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| 108 | is ill-formed if the initial <code>sizeof(PyObject)</code> bytes of |
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| 109 | <code>Y</code> are not layout-compatible with <code>PyObject</code>.</p> |
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| 110 | |
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| 111 | <h4><a name="handle-spec-synopsis"></a>Class template handle |
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| 112 | synopsis</h4> |
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| 113 | <pre> |
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| 114 | namespace boost { namespace python |
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| 115 | { |
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| 116 | template <class T> |
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| 117 | class handle |
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| 118 | { |
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| 119 | typedef <i>unspecified-member-function-pointer</i> bool_type; |
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| 120 | |
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| 121 | public: // types |
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| 122 | typedef T element_type; |
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| 123 | |
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| 124 | public: // member functions |
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| 125 | ~handle(); |
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| 126 | |
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| 127 | template <class Y> |
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| 128 | explicit handle(detail::borrowed<null_ok<Y> >* p); |
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| 129 | |
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| 130 | template <class Y> |
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| 131 | explicit handle(null_ok<detail::borrowed<Y> >* p); |
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| 132 | |
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| 133 | template <class Y> |
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| 134 | explicit handle(detail::borrowed<Y>* p); |
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| 135 | |
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| 136 | template <class Y> |
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| 137 | explicit handle(null_ok<Y>* p); |
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| 138 | |
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| 139 | template <class Y> |
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| 140 | explicit handle(Y* p); |
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| 141 | |
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| 142 | handle(); |
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| 143 | |
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| 144 | handle& operator=(handle const& r); |
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| 145 | |
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| 146 | template<typename Y> |
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| 147 | handle& operator=(handle<Y> const & r); // never throws |
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| 148 | |
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| 149 | |
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| 150 | template <typename Y> |
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| 151 | handle(handle<Y> const& r); |
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| 152 | |
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| 153 | handle(handle const& r); |
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| 154 | |
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| 155 | T* operator-> () const; |
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| 156 | T& operator* () const; |
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| 157 | T* get() const; |
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| 158 | void reset(); |
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| 159 | T* release(); |
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| 160 | |
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| 161 | operator bool_type() const; // never throws |
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| 162 | private: |
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| 163 | T* m_p; |
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| 164 | }; |
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| 165 | |
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| 166 | template <class T> struct null_ok; |
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| 167 | namespace detail { template <class T> struct borrowed; } |
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| 168 | }} |
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| 169 | </pre> |
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| 170 | |
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| 171 | <h4><a name="handle-spec-ctors">Class <code>handle</code> constructors |
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| 172 | and destructor</a></h4> |
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| 173 | <pre> |
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| 174 | virtual ~handle(); |
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| 175 | </pre> |
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| 176 | |
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| 177 | <dl class="function-semantics"> |
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| 178 | <dt><b>Effects:</b> |
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| 179 | <code>Py_XDECREF(</code><i>upcast</i><code><PyObject*>(m_p))</code></dt> |
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| 180 | </dl> |
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| 181 | <pre> |
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| 182 | template <class Y> |
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| 183 | explicit handle(detail::borrowed<null_ok<Y> >* p); |
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| 184 | </pre> |
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| 185 | |
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| 186 | <dl class="function-semantics"> |
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| 187 | <dt><b>Effects:</b> |
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| 188 | <code>Py_XINCREF(</code><i>upcast</i><code><PyObject*>(p)); |
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| 189 | m_p = </code><i>upcast</i><code><T*>(p);</code></dt> |
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| 190 | </dl> |
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| 191 | <pre> |
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| 192 | template <class Y> |
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| 193 | explicit handle(null_ok<detail::borrowed<Y> >* p); |
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| 194 | </pre> |
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| 195 | |
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| 196 | <dl class="function-semantics"> |
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| 197 | <dt><b>Effects:</b> |
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| 198 | <code>Py_XINCREF(</code><i>upcast</i><code><PyObject*>(p)); |
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| 199 | m_p = </code><i>upcast</i><code><T*>(p);</code></dt> |
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| 200 | </dl> |
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| 201 | <pre> |
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| 202 | template <class Y> |
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| 203 | explicit handle(detail::borrowed<Y>* p); |
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| 204 | </pre> |
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| 205 | |
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| 206 | <dl class="function-semantics"> |
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| 207 | <dt><b>Effects:</b> |
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| 208 | <code>Py_XINCREF(</code><i>upcast</i><code><PyObject*>(p)); |
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| 209 | m_p = </code><i>upcast</i><code><T*>(<a href= |
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| 210 | "errors.html#expect_non_null-spec">expect_non_null</a>(p));</code></dt> |
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| 211 | </dl> |
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| 212 | <pre> |
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| 213 | template <class Y> |
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| 214 | explicit handle(null_ok<Y>* p); |
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| 215 | </pre> |
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| 216 | |
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| 217 | <dl class="function-semantics"> |
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| 218 | <dt><b>Effects:</b> |
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| 219 | <code>m_p = </code><i>upcast</i><code><T*>(p);</code></dt> |
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| 220 | </dl> |
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| 221 | <pre> |
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| 222 | template <class Y> |
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| 223 | explicit handle(Y* p); |
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| 224 | </pre> |
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| 225 | |
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| 226 | <dl class="function-semantics"> |
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| 227 | <dt><b>Effects:</b> |
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| 228 | <code>m_p = </code><i>upcast</i><code><T*>(<a href= |
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| 229 | "errors.html#expect_non_null-spec">expect_non_null</a>(p));</code></dt> |
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| 230 | </dl> |
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| 231 | <pre> |
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| 232 | handle(); |
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| 233 | </pre> |
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| 234 | |
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| 235 | <dl class="function-semantics"> |
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| 236 | <dt><b>Effects:</b> <code>m_p = 0;</code></dt> |
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| 237 | </dl> |
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| 238 | <pre> |
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| 239 | template <typename Y> |
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| 240 | handle(handle<Y> const& r); |
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| 241 | handle(handle const& r); |
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| 242 | </pre> |
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| 243 | |
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| 244 | <dl class="function-semantics"> |
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| 245 | <dt><b>Effects:</b> |
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| 246 | <code>m_p = r.m_p; Py_XINCREF(</code><i>upcast</i><code><PyObject*>(m_p));</code></dt> |
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| 247 | </dl> |
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| 248 | |
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| 249 | <h4><a name="handle-spec-modifiers">Class <code>handle</code> |
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| 250 | modifiers</a></h4> |
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| 251 | <pre> |
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| 252 | handle& operator=(handle const& r); |
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| 253 | template<typename Y> |
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| 254 | handle& operator=(handle<Y> const & r); // never throws |
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| 255 | </pre> |
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| 256 | |
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| 257 | <dl class="function-semantics"> |
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| 258 | <dt><b>Effects:</b> |
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| 259 | <code>Py_XINCREF(</code><i>upcast</i><code><PyObject*>(r.m_p)); Py_XDECREF(</code><i> |
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| 260 | upcast</i><code><PyObject*>(m_p)); m_p = r.m_p;</code></dt> |
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| 261 | </dl> |
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| 262 | <pre> |
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| 263 | T* release(); |
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| 264 | </pre> |
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| 265 | |
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| 266 | <dl class="function-semantics"> |
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| 267 | <dt><b>Effects:</b> <code>T* x = m_p; m_p = 0;return |
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| 268 | x;</code></dt> |
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| 269 | </dl> |
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| 270 | <pre> |
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| 271 | void reset(); |
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| 272 | </pre> |
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| 273 | |
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| 274 | <dl class="function-semantics"> |
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| 275 | <dt><b>Effects:</b> |
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| 276 | <code>*this = handle<T>();</code></dt> |
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| 277 | </dl> |
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| 278 | |
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| 279 | <h4><a name="handle-spec-observers">Class <code>handle</code> |
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| 280 | observers</a></h4> |
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| 281 | <pre> |
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| 282 | T* operator-> () const; |
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| 283 | T* get() const; |
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| 284 | </pre> |
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| 285 | |
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| 286 | <dl class="function-semantics"> |
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| 287 | <dt><b>Returns:</b> <code>m_p;</code></dt> |
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| 288 | </dl> |
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| 289 | <pre> |
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| 290 | T& operator* () const; |
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| 291 | </pre> |
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| 292 | |
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| 293 | <dl class="function-semantics"> |
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| 294 | <dt><b>Returns:</b> <code>*m_p;</code></dt> |
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| 295 | </dl> |
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| 296 | <pre> |
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| 297 | operator bool_type() const; // never throws |
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| 298 | </pre> |
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| 299 | |
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| 300 | <dl class="function-semantics"> |
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| 301 | <dt><b>Returns:</b> 0 if <code>m_p == 0</code>, a pointer |
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| 302 | convertible to <code>true</code> otherwise.</dt> |
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| 303 | </dl> |
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| 304 | |
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| 305 | <h2><a name="functions"></a>Functions</h2> |
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| 306 | |
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| 307 | <h3><a name="borrowed-spec"></a><code>borrowed</code></h3> |
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| 308 | <pre> |
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| 309 | template <class T> |
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| 310 | detail::borrowed<T>* borrowed(T* p) |
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| 311 | { |
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| 312 | return (detail::borrowed<T>*)p; |
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| 313 | } |
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| 314 | </pre> |
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| 315 | |
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| 316 | <h3><a name="allow_null-spec"></a><code>allow_null</code></h3> |
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| 317 | <pre> |
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| 318 | template <class T> |
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| 319 | null_ok<T>* allow_null(T* p) |
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| 320 | { |
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| 321 | return (null_ok<T>*)p; |
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| 322 | } |
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| 323 | </pre> |
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| 324 | |
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| 325 | <p>Revised |
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| 326 | <!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B, %Y" startspan --> |
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| 327 | 13 November, 2002 |
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| 328 | <!--webbot bot="Timestamp" endspan i-checksum="39359" --> |
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| 329 | </p> |
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| 330 | |
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| 331 | <p class="c4">© Copyright <a href= |
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| 332 | "../../../../people/dave_abrahams.htm">Dave Abrahams</a> 2002 |
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| 333 | .</p> |
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| 334 | </body> |
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| 335 | </html> |
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| 336 | |
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