1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>boost/python/scope.hpp</title> 5<link rel="stylesheet" href="../../boostbook.css" type="text/css"> 6<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 7<link rel="home" href="../index.html" title="Boost.Python Reference Manual"> 8<link rel="up" href="../high_level_components.html" title="Chapter 2. High Level Components"> 9<link rel="prev" href="boost_python_operators_hpp.html" title="boost/python/operators.hpp"> 10<link rel="next" href="boost_python_stl_iterator_hpp.html" title="boost/python/stl_iterator.hpp"> 11</head> 12<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 13<table cellpadding="2" width="100%"><tr><td valign="top"><img alt="" width="" height="" src="../../images/boost.png"></td></tr></table> 14<hr> 15<div class="spirit-nav"> 16<a accesskey="p" href="boost_python_operators_hpp.html"><img src="../../images/prev.png" alt="Prev"></a><a accesskey="u" href="../high_level_components.html"><img src="../../images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../images/home.png" alt="Home"></a><a accesskey="n" href="boost_python_stl_iterator_hpp.html"><img src="../../images/next.png" alt="Next"></a> 17</div> 18<div class="section"> 19<div class="titlepage"><div><div><h2 class="title" style="clear: both"> 20<a name="high_level_components.boost_python_scope_hpp"></a><a class="link" href="boost_python_scope_hpp.html" title="boost/python/scope.hpp">boost/python/scope.hpp</a> 21</h2></div></div></div> 22<div class="toc"><dl class="toc"> 23<dt><span class="section"><a href="boost_python_scope_hpp.html#high_level_components.boost_python_scope_hpp.introduction">Introduction</a></span></dt> 24<dt><span class="section"><a href="boost_python_scope_hpp.html#high_level_components.boost_python_scope_hpp.class_scope">Class 25 <code class="computeroutput"><span class="identifier">scope</span></code></a></span></dt> 26<dt><span class="section"><a href="boost_python_scope_hpp.html#high_level_components.boost_python_scope_hpp.class_scope_constructors_and_des">Class 27 scope constructors and destructor</a></span></dt> 28<dt><span class="section"><a href="boost_python_scope_hpp.html#high_level_components.boost_python_scope_hpp.example">Example</a></span></dt> 29</dl></div> 30<div class="section"> 31<div class="titlepage"><div><div><h3 class="title"> 32<a name="high_level_components.boost_python_scope_hpp.introduction"></a><a class="link" href="boost_python_scope_hpp.html#high_level_components.boost_python_scope_hpp.introduction" title="Introduction">Introduction</a> 33</h3></div></div></div> 34<p> 35 Defines facilities for querying and controlling the Python scope (namespace) 36 which will contain new wrapped classes and functions. 37 </p> 38</div> 39<div class="section"> 40<div class="titlepage"><div><div><h3 class="title"> 41<a name="high_level_components.boost_python_scope_hpp.class_scope"></a><a class="link" href="boost_python_scope_hpp.html#high_level_components.boost_python_scope_hpp.class_scope" title="Class scope">Class 42 <code class="computeroutput"><span class="identifier">scope</span></code></a> 43</h3></div></div></div> 44<p> 45 The scope class has an associated global Python object which controls the 46 Python namespace in which new extension classes and wrapped functions will 47 be defined as attributes. Default-constructing a new scope object binds 48 it to the associated global Python object. Constructing a scope object 49 with an argument changes the associated global Python object to the one 50 held by the argument, until the lifetime of the scope object ends, at which 51 time the associated global Python object reverts to what it was before 52 the scope object was constructed. 53 </p> 54<pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span> <span class="keyword">namespace</span> <span class="identifier">python</span> 55<span class="special">{</span> 56 <span class="keyword">class</span> <span class="identifier">scope</span> <span class="special">:</span> <span class="keyword">public</span> <span class="identifier">object</span> 57 <span class="special">{</span> 58 <span class="keyword">public</span><span class="special">:</span> 59 <span class="identifier">scope</span><span class="special">(</span><span class="identifier">scope</span> <span class="keyword">const</span><span class="special">&);</span> 60 <span class="identifier">scope</span><span class="special">(</span><span class="identifier">object</span> <span class="keyword">const</span><span class="special">&);</span> 61 <span class="identifier">scope</span><span class="special">();</span> 62 <span class="special">~</span><span class="identifier">scope</span><span class="special">()</span> 63 <span class="keyword">private</span><span class="special">:</span> 64 <span class="keyword">void</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">scope</span> <span class="keyword">const</span><span class="special">&);</span> 65 <span class="special">};</span> 66<span class="special">}}</span> 67</pre> 68</div> 69<div class="section"> 70<div class="titlepage"><div><div><h3 class="title"> 71<a name="high_level_components.boost_python_scope_hpp.class_scope_constructors_and_des"></a><a class="link" href="boost_python_scope_hpp.html#high_level_components.boost_python_scope_hpp.class_scope_constructors_and_des" title="Class scope constructors and destructor">Class 72 scope constructors and destructor</a> 73</h3></div></div></div> 74<pre class="programlisting"><span class="keyword">explicit</span> <span class="identifier">scope</span><span class="special">(</span><span class="identifier">scope</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">x</span><span class="special">);</span> 75<span class="keyword">explicit</span> <span class="identifier">scope</span><span class="special">(</span><span class="identifier">object</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">x</span><span class="special">);</span> 76</pre> 77<p> 78 Stores a reference to the current associated scope object, and sets the 79 associated scope object to the one referred to by x.ptr(). The object base 80 class is initialized with x. 81 </p> 82<pre class="programlisting"><span class="identifier">scope</span><span class="special">();</span></pre> 83<p> 84 Stores a reference to the current associated scope object. The object base 85 class is initialized with the current associated scope object. Outside 86 any module initialization function, the current associated Python object 87 is None. 88 </p> 89<pre class="programlisting"><span class="special">~</span><span class="identifier">scope</span><span class="special">()</span></pre> 90<p> 91 Sets the current associated Python object to the stored object. 92 </p> 93</div> 94<div class="section"> 95<div class="titlepage"><div><div><h3 class="title"> 96<a name="high_level_components.boost_python_scope_hpp.example"></a><a class="link" href="boost_python_scope_hpp.html#high_level_components.boost_python_scope_hpp.example" title="Example">Example</a> 97</h3></div></div></div> 98<p> 99 The following example shows how scope setting can be used to define nested 100 classes. 101 </p> 102<p> 103 C++ Module definition: 104 </p> 105<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">python</span><span class="special">/</span><span class="identifier">module</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 106<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">python</span><span class="special">/</span><span class="keyword">class</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 107<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">python</span><span class="special">/</span><span class="identifier">scope</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 108<span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">python</span><span class="special">;</span> 109 110<span class="keyword">struct</span> <span class="identifier">X</span> 111<span class="special">{</span> 112 <span class="keyword">void</span> <span class="identifier">f</span><span class="special">()</span> <span class="special">{}</span> 113 114 <span class="keyword">struct</span> <span class="identifier">Y</span> <span class="special">{</span> <span class="keyword">int</span> <span class="identifier">g</span><span class="special">()</span> <span class="special">{</span> <span class="keyword">return</span> <span class="number">42</span><span class="special">;</span> <span class="special">}</span> <span class="special">};</span> 115<span class="special">};</span> 116 117<span class="identifier">BOOST_PYTHON_MODULE</span><span class="special">(</span><span class="identifier">nested</span><span class="special">)</span> 118<span class="special">{</span> 119 <span class="comment">// add some constants to the current (module) scope</span> 120 <span class="identifier">scope</span><span class="special">().</span><span class="identifier">attr</span><span class="special">(</span><span class="string">"yes"</span><span class="special">)</span> <span class="special">=</span> <span class="number">1</span><span class="special">;</span> 121 <span class="identifier">scope</span><span class="special">().</span><span class="identifier">attr</span><span class="special">(</span><span class="string">"no"</span><span class="special">)</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span> 122 123 <span class="comment">// Change the current scope </span> 124 <span class="identifier">scope</span> <span class="identifier">outer</span> 125 <span class="special">=</span> <span class="identifier">class_</span><span class="special"><</span><span class="identifier">X</span><span class="special">>(</span><span class="string">"X"</span><span class="special">)</span> 126 <span class="special">.</span><span class="identifier">def</span><span class="special">(</span><span class="string">"f"</span><span class="special">,</span> <span class="special">&</span><span class="identifier">X</span><span class="special">::</span><span class="identifier">f</span><span class="special">)</span> 127 <span class="special">;</span> 128 129 <span class="comment">// Define a class Y in the current scope, X</span> 130 <span class="identifier">class_</span><span class="special"><</span><span class="identifier">X</span><span class="special">::</span><span class="identifier">Y</span><span class="special">>(</span><span class="string">"Y"</span><span class="special">)</span> 131 <span class="special">.</span><span class="identifier">def</span><span class="special">(</span><span class="string">"g"</span><span class="special">,</span> <span class="special">&</span><span class="identifier">X</span><span class="special">::</span><span class="identifier">Y</span><span class="special">::</span><span class="identifier">g</span><span class="special">)</span> 132 <span class="special">;</span> 133<span class="special">}</span> 134</pre> 135<p> 136 Interactive Python: 137 </p> 138<pre class="programlisting"><span class="special">>>></span> <span class="identifier">import</span> <span class="identifier">nested</span> 139<span class="special">>>></span> <span class="identifier">nested</span><span class="special">.</span><span class="identifier">yes</span> 140<span class="number">1</span> 141<span class="special">>>></span> <span class="identifier">y</span> <span class="special">=</span> <span class="identifier">nested</span><span class="special">.</span><span class="identifier">X</span><span class="special">.</span><span class="identifier">Y</span><span class="special">()</span> 142<span class="special">>>></span> <span class="identifier">y</span><span class="special">.</span><span class="identifier">g</span><span class="special">()</span> 143<span class="number">42</span> 144</pre> 145</div> 146</div> 147<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 148<td align="left"></td> 149<td align="right"><div class="copyright-footer">Copyright © 2002-2005, 2015 David Abrahams, Stefan Seefeld<p> 150 Distributed under the Boost Software License, Version 1.0. (See accompanying 151 file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a> 152 </p> 153</div></td> 154</tr></table> 155<hr> 156<div class="spirit-nav"> 157<a accesskey="p" href="boost_python_operators_hpp.html"><img src="../../images/prev.png" alt="Prev"></a><a accesskey="u" href="../high_level_components.html"><img src="../../images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../images/home.png" alt="Home"></a><a accesskey="n" href="boost_python_stl_iterator_hpp.html"><img src="../../images/next.png" alt="Next"></a> 158</div> 159</body> 160</html> 161
