libs/python/doc/html/reference/high_level_components/boost_python_wrapper_hpp.html


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
<title>boost/python/wrapper.hpp</title>
<link rel="stylesheet" href="../../boostbook.css" type="text/css">
<meta name="generator" content="DocBook XSL Stylesheets V1.76.1">
<link rel="home" href="../index.html" title="Boost.Python Reference Manual">
<link rel="up" href="../high_level_components.html" title="Chapter&#160;2.&#160;High Level Components">
<link rel="prev" href="boost_python_stl_iterator_hpp.html" title="boost/python/stl_iterator.hpp">
<link rel="next" href="../object_wrappers.html" title="Chapter&#160;3.&#160;Object Wrappers">
</head>
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
<table cellpadding="2" width="100%"><tr><td valign="top"><img alt="" width="" height="" src="../../images/boost.png"></td></tr></table>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="boost_python_stl_iterator_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="../object_wrappers.html"><img src="../../images/next.png" alt="Next"></a>
</div>
<div class="section">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="high_level_components.boost_python_wrapper_hpp"></a><a class="link" href="boost_python_wrapper_hpp.html" title="boost/python/wrapper.hpp">boost/python/wrapper.hpp</a>
</h2></div></div></div>
<div class="toc"><dl>
<dt><span class="section"><a href="boost_python_wrapper_hpp.html#high_level_components.boost_python_wrapper_hpp.introduction">Introduction</a></span></dt>
<dt><span class="section"><a href="boost_python_wrapper_hpp.html#high_level_components.boost_python_wrapper_hpp.class_override">Class
        <code class="computeroutput"><span class="identifier">override</span></code></a></span></dt>
<dt><span class="section"><a href="boost_python_wrapper_hpp.html#high_level_components.boost_python_wrapper_hpp.class_override_observer_function">Class
        <code class="computeroutput"><span class="identifier">override</span></code> observer functions</a></span></dt>
<dt><span class="section"><a href="boost_python_wrapper_hpp.html#high_level_components.boost_python_wrapper_hpp.class_template_wrapper">Class
        template <code class="computeroutput"><span class="identifier">wrapper</span></code></a></span></dt>
<dt><span class="section"><a href="boost_python_wrapper_hpp.html#high_level_components.boost_python_wrapper_hpp.class_template_wrapper_observer_">Class
        template <code class="computeroutput"><span class="identifier">wrapper</span></code> observer
        functions</a></span></dt>
<dt><span class="section"><a href="boost_python_wrapper_hpp.html#high_level_components.boost_python_wrapper_hpp.example">Example</a></span></dt>
</dl></div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="high_level_components.boost_python_wrapper_hpp.introduction"></a><a class="link" href="boost_python_wrapper_hpp.html#high_level_components.boost_python_wrapper_hpp.introduction" title="Introduction">Introduction</a>
</h3></div></div></div>
<p>
          To wrap a class T such that its virtual functions can be "overridden
          in Python"&#8212;so that the corresponding method of a Python derived
          class will be called when the virtual function is invoked from C++&#8212;you
          must create a C++ wrapper class derived from <code class="computeroutput"><span class="identifier">T</span></code>
          that overrides those virtual functions so that they call into Python. This
          header contains classes that can be used to make that job easier.
        </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="high_level_components.boost_python_wrapper_hpp.class_override"></a><a class="link" href="boost_python_wrapper_hpp.html#high_level_components.boost_python_wrapper_hpp.class_override" title="Class override">Class
        <code class="computeroutput"><span class="identifier">override</span></code></a>
</h3></div></div></div>
<p>
          Encapsulates a Python override of a C++ virtual function. An override object
          either holds a callable Python object or <code class="computeroutput"><span class="identifier">None</span></code>.
        </p>
<pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">boost</span>
<span class="special">{</span>
  <span class="keyword">class</span> <span class="identifier">override</span> <span class="special">:</span> <span class="identifier">object</span>
  <span class="special">{</span>
   <span class="keyword">public</span><span class="special">:</span>
      <span class="identifier">unspecified</span> <span class="keyword">operator</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span>
      <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">A0</span><span class="special">&gt;</span>
      <span class="identifier">unspecified</span> <span class="keyword">operator</span><span class="special">(</span><span class="identifier">A0</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
      <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">A0</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">A1</span><span class="special">&gt;</span>
      <span class="identifier">unspecified</span> <span class="keyword">operator</span><span class="special">(</span><span class="identifier">A0</span><span class="special">,</span> <span class="identifier">A1</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
      <span class="special">...</span>
      <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">A0</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">A1</span><span class="special">,</span> <span class="special">...</span><span class="keyword">class</span> <span class="identifier">An</span><span class="special">&gt;</span>
      <span class="identifier">unspecified</span> <span class="keyword">operator</span><span class="special">(</span><span class="identifier">A0</span><span class="special">,</span> <span class="identifier">A1</span><span class="special">,</span> <span class="special">...</span><span class="identifier">An</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  <span class="special">};</span>
<span class="special">};</span>
</pre>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="high_level_components.boost_python_wrapper_hpp.class_override_observer_function"></a><a class="link" href="boost_python_wrapper_hpp.html#high_level_components.boost_python_wrapper_hpp.class_override_observer_function" title="Class override observer functions">Class
        <code class="computeroutput"><span class="identifier">override</span></code> observer functions</a>
</h3></div></div></div>
<pre class="programlisting"><span class="identifier">unspecified</span> <span class="keyword">operator</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span>
<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">A0</span><span class="special">&gt;</span>
<span class="identifier">unspecified</span> <span class="keyword">operator</span><span class="special">(</span><span class="identifier">A0</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">A0</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">A1</span><span class="special">&gt;</span>
<span class="identifier">unspecified</span> <span class="keyword">operator</span><span class="special">(</span><span class="identifier">A0</span><span class="special">,</span> <span class="identifier">A1</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
<span class="special">...</span>
<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">A0</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">A1</span><span class="special">,</span> <span class="special">...</span><span class="keyword">class</span> <span class="identifier">An</span><span class="special">&gt;</span>
<span class="identifier">unspecified</span> <span class="keyword">operator</span><span class="special">(</span><span class="identifier">A0</span><span class="special">,</span> <span class="identifier">A1</span><span class="special">,</span> <span class="special">...</span><span class="identifier">An</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl>
<dt><span class="term">Effects</span></dt>
<dd><p>
                If *this holds a callable Python object, it is invoked with the specified
                arguments in the manner specified here. Otherwise, throws <a class="link" href="boost_python_errors_hpp.html#high_level_components.boost_python_errors_hpp.class_error_already_set" title="Class error_already_set">error_already_set</a>.
              </p></dd>
<dt><span class="term">Returns</span></dt>
<dd><p>
                An object of unspecified type that holds the Python result of the
                invocation and, when converted to a C++ type R, attempts to convert
                that result object to R. If that conversion fails, throws <a class="link" href="boost_python_errors_hpp.html#high_level_components.boost_python_errors_hpp.class_error_already_set" title="Class error_already_set">error_already_set</a>.
              </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="high_level_components.boost_python_wrapper_hpp.class_template_wrapper"></a><a class="link" href="boost_python_wrapper_hpp.html#high_level_components.boost_python_wrapper_hpp.class_template_wrapper" title="Class template wrapper">Class
        template <code class="computeroutput"><span class="identifier">wrapper</span></code></a>
</h3></div></div></div>
<p>
          Deriving your wrapper class from both <code class="computeroutput"><span class="identifier">T</span></code>
          and <code class="computeroutput"><span class="identifier">wrapper</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span></code>
          makes writing that derived class easier.
        </p>
<pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">boost</span>
<span class="special">{</span>
  <span class="keyword">class</span> <span class="identifier">wrapper</span>
  <span class="special">{</span>
   <span class="keyword">protected</span><span class="special">:</span>
      <span class="identifier">override</span> <span class="identifier">get_override</span><span class="special">(</span><span class="keyword">char</span> <span class="keyword">const</span><span class="special">*</span> <span class="identifier">name</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  <span class="special">};</span>
<span class="special">};</span>
</pre>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="high_level_components.boost_python_wrapper_hpp.class_template_wrapper_observer_"></a><a class="link" href="boost_python_wrapper_hpp.html#high_level_components.boost_python_wrapper_hpp.class_template_wrapper_observer_" title="Class template wrapper observer functions">Class
        template <code class="computeroutput"><span class="identifier">wrapper</span></code> observer
        functions</a>
</h3></div></div></div>
<pre class="programlisting"><span class="identifier">override</span> <span class="identifier">get_override</span><span class="special">(</span><span class="keyword">char</span> <span class="keyword">const</span><span class="special">*</span> <span class="identifier">name</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl>
<dt><span class="term">Requires</span></dt>
<dd><p>
                name is a <a class="link" href="../glossary.html#ntbs">ntbs</a>.
              </p></dd>
<dt><span class="term">Returns</span></dt>
<dd><p>
                If <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                is the C++ base class subobject of a Python derived class instance
                that overrides the named function, returns an override object that
                delegates to the Python override. Otherwise, returns an override
                object that holds <code class="computeroutput"><span class="identifier">None</span></code>.
              </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="high_level_components.boost_python_wrapper_hpp.example"></a><a class="link" href="boost_python_wrapper_hpp.html#high_level_components.boost_python_wrapper_hpp.example" title="Example">Example</a>
</h3></div></div></div>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</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">&gt;</span>
<span class="preprocessor">#include</span> <span class="special">&lt;</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">&gt;</span>
<span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">python</span><span class="special">/</span><span class="identifier">wrapper</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
<span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">python</span><span class="special">/</span><span class="identifier">call</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>

<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>

<span class="comment">// Class with one pure virtual function</span>
<span class="keyword">struct</span> <span class="identifier">P</span>
<span class="special">{</span>
    <span class="keyword">virtual</span> <span class="special">~</span><span class="identifier">P</span><span class="special">(){}</span>
    <span class="keyword">virtual</span> <span class="keyword">char</span> <span class="keyword">const</span><span class="special">*</span> <span class="identifier">f</span><span class="special">()</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span>
    <span class="keyword">char</span> <span class="keyword">const</span><span class="special">*</span> <span class="identifier">g</span><span class="special">()</span> <span class="special">{</span> <span class="keyword">return</span> <span class="string">"P::g()"</span><span class="special">;</span> <span class="special">}</span>
<span class="special">};</span>

<span class="keyword">struct</span> <span class="identifier">PCallback</span> <span class="special">:</span> <span class="identifier">P</span><span class="special">,</span> <span class="identifier">wrapper</span><span class="special">&lt;</span><span class="identifier">P</span><span class="special">&gt;</span>
<span class="special">{</span>
    <span class="keyword">char</span> <span class="keyword">const</span><span class="special">*</span> <span class="identifier">f</span><span class="special">()</span>
    <span class="special">{</span>
        <span class="keyword">return</span> <span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get_override</span><span class="special">(</span><span class="string">"f"</span><span class="special">)();</span>
    <span class="special">}</span>
<span class="special">};</span>

<span class="comment">// Class with one non-pure virtual function</span>
<span class="keyword">struct</span> <span class="identifier">A</span>
<span class="special">{</span>
    <span class="keyword">virtual</span> <span class="special">~</span><span class="identifier">A</span><span class="special">(){}</span>
    <span class="keyword">virtual</span> <span class="keyword">char</span> <span class="keyword">const</span><span class="special">*</span> <span class="identifier">f</span><span class="special">()</span> <span class="special">{</span> <span class="keyword">return</span> <span class="string">"A::f()"</span><span class="special">;</span> <span class="special">}</span>
<span class="special">};</span>

<span class="keyword">struct</span> <span class="identifier">ACallback</span> <span class="special">:</span>  <span class="identifier">A</span><span class="special">,</span> <span class="identifier">wrapper</span><span class="special">&lt;</span><span class="identifier">A</span><span class="special">&gt;</span>
<span class="special">{</span>
    <span class="keyword">char</span> <span class="keyword">const</span><span class="special">*</span> <span class="identifier">f</span><span class="special">()</span>
    <span class="special">{</span>
        <span class="keyword">if</span> <span class="special">(</span><span class="identifier">override</span> <span class="identifier">f</span> <span class="special">=</span> <span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get_override</span><span class="special">(</span><span class="string">"f"</span><span class="special">))</span>
            <span class="keyword">return</span> <span class="identifier">f</span><span class="special">();</span>
        <span class="keyword">return</span> <span class="identifier">A</span><span class="special">::</span><span class="identifier">f</span><span class="special">();</span>
    <span class="special">}</span>

    <span class="keyword">char</span> <span class="keyword">const</span><span class="special">*</span> <span class="identifier">default_f</span><span class="special">()</span> <span class="special">{</span> <span class="keyword">return</span> <span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">A</span><span class="special">::</span><span class="identifier">f</span><span class="special">();</span> <span class="special">}</span>
<span class="special">};</span>

<span class="identifier">BOOST_PYTHON_MODULE_INIT</span><span class="special">(</span><span class="identifier">polymorphism</span><span class="special">)</span>
<span class="special">{</span>
    <span class="identifier">class_</span><span class="special">&lt;</span><span class="identifier">PCallback</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">noncopyable</span><span class="special">&gt;(</span><span class="string">"P"</span><span class="special">)</span>
        <span class="special">.</span><span class="identifier">def</span><span class="special">(</span><span class="string">"f"</span><span class="special">,</span> <span class="identifier">pure_virtual</span><span class="special">(&amp;</span><span class="identifier">P</span><span class="special">::</span><span class="identifier">f</span><span class="special">))</span>
        <span class="special">;</span>

    <span class="identifier">class_</span><span class="special">&lt;</span><span class="identifier">ACallback</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">noncopyable</span><span class="special">&gt;(</span><span class="string">"A"</span><span class="special">)</span>
        <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">&amp;</span><span class="identifier">A</span><span class="special">::</span><span class="identifier">f</span><span class="special">,</span> <span class="special">&amp;</span><span class="identifier">ACallback</span><span class="special">::</span><span class="identifier">default_f</span><span class="special">)</span>
        <span class="special">;</span>
<span class="special">}</span>
</pre>
</div>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"></td>
<td align="right"><div class="copyright-footer">Copyright &#169; 2002-2005, 2015 David Abrahams, Stefan Seefeld<p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        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>
      </p>
</div></td>
</tr></table>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="boost_python_stl_iterator_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="../object_wrappers.html"><img src="../../images/next.png" alt="Next"></a>
</div>
</body>
</html>