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| <h1 class="c1"><a href="../index.html">Boost.Python</a></h1> |
| |
| <h2 class="c2">Header <boost/python/handle.hpp></h2> |
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| |
| <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 |
| <!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B, %Y" startspan --> |
| 13 November, 2002 |
| <!--webbot bot="Timestamp" endspan i-checksum="39359" --> |
| </p> |
| |
| <p class="c4">© Copyright <a href= |
| "http://www.boost.org/people/dave_abrahams.htm">Dave Abrahams</a> 2002 |
| .</p> |
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