Planet
navi homePPSaboutscreenshotsdownloaddevelopmentforum

source: downloads/boost_1_34_1/libs/python/pyste/doc/templates.html @ 69

Last change on this file since 69 was 29, checked in by landauf, 17 years ago

updated boost from 1_33_1 to 1_34_1
File size: 8.8 KB
Line 
1<html>
2<head>
3<!-- Generated by the Spirit (http://spirit.sf.net) QuickDoc -->
4<title>Templates</title>
5<link rel="stylesheet" href="theme/style.css" type="text/css">
6<link rel="prev" href="policies.html">
7<link rel="next" href="wrappers.html">
8</head>
9<body>
10<table width="100%" height="48" border="0" cellspacing="2">
11  <tr>
12    <td><img src="../../../../boost.png">
13    </td>
14    <td width="85%">
15      <font size="6" face="Verdana, Arial, Helvetica, sans-serif"><b>Templates</b></font>
16    </td>
17  </tr>
18</table>
19<br>
20<table border="0">
21  <tr>
22    <td width="30"><a href="../index.html"><img src="theme/u_arr.gif" border="0"></a></td>
23    <td width="30"><a href="policies.html"><img src="theme/l_arr.gif" border="0"></a></td>
24    <td width="20"><a href="wrappers.html"><img src="theme/r_arr.gif" border="0"></a></td>
25   </tr>
26</table>
27<p>
28Template classes can easily be exported too, but you can't export the template
29itself... you have to export instantiations of it! So, if you want to export a
30<tt>std::vector</tt>, you will have to export vectors of int, doubles, etc.</p>
31<p>
32Suppose we have this code:</p>
33<code><pre>
34    <span class=keyword>template </span><span class=special>&lt;</span><span class=keyword>class </span><span class=identifier>T</span><span class=special>&gt;
35    </span><span class=keyword>struct </span><span class=identifier>Point
36    </span><span class=special>{
37        </span><span class=identifier>T </span><span class=identifier>x</span><span class=special>;
38        </span><span class=identifier>T </span><span class=identifier>y</span><span class=special>;
39    };
40</span></pre></code>
41<p>
42And we want to export <tt>Point</tt>s of int and double:</p>
43<code><pre>
44    <span class=identifier>Point </span><span class=special>= </span><span class=identifier>Template</span><span class=special>(</span><span class=string>&quot;Point&quot;</span><span class=special>, </span><span class=string>&quot;point.h&quot;</span><span class=special>)
45    </span><span class=identifier>Point</span><span class=special>(</span><span class=string>&quot;int&quot;</span><span class=special>)
46    </span><span class=identifier>Point</span><span class=special>(</span><span class=string>&quot;double&quot;</span><span class=special>)
47</span></pre></code>
48<p>
49Pyste will assign default names for each instantiation. In this example, those
50would be &quot;<tt>Point_int</tt>&quot; and &quot;<tt>Point_double</tt>&quot;, but most of the time users will want to
51rename the instantiations:</p>
52<code><pre>
53    <span class=identifier>Point</span><span class=special>(</span><span class=string>&quot;int&quot;</span><span class=special>, </span><span class=string>&quot;IPoint&quot;</span><span class=special>)         // </span><span class=identifier>renames </span><span class=identifier>the </span><span class=identifier>instantiation
54    </span><span class=identifier>double_inst </span><span class=special>= </span><span class=identifier>Point</span><span class=special>(</span><span class=string>&quot;double&quot;</span><span class=special>)  // </span><span class=identifier>another </span><span class=identifier>way </span><span class=identifier>to </span><span class=keyword>do </span><span class=identifier>the </span><span class=identifier>same
55    </span><span class=identifier>rename</span><span class=special>(</span><span class=identifier>double_inst</span><span class=special>, </span><span class=string>&quot;DPoint&quot;</span><span class=special>)
56</span></pre></code>
57<p>
58Note that you can rename, exclude, set policies, etc, in the <tt>Template</tt> object
59like you would do with a <tt>Function</tt> or a <tt>Class</tt>. This changes affect all
60<b>future</b> instantiations:</p>
61<code><pre>
62    <span class=identifier>Point </span><span class=special>= </span><span class=identifier>Template</span><span class=special>(</span><span class=string>&quot;Point&quot;</span><span class=special>, </span><span class=string>&quot;point.h&quot;</span><span class=special>)
63    </span><span class=identifier>Point</span><span class=special>(</span><span class=string>&quot;float&quot;</span><span class=special>, </span><span class=string>&quot;FPoint&quot;</span><span class=special>)        // </span><span class=identifier>will </span><span class=identifier>have </span><span class=identifier>x </span><span class=keyword>and </span><span class=identifier>y </span><span class=identifier>as </span><span class=identifier>data </span><span class=identifier>members
64    </span><span class=identifier>rename</span><span class=special>(</span><span class=identifier>Point</span><span class=special>.</span><span class=identifier>x</span><span class=special>, </span><span class=string>&quot;X&quot;</span><span class=special>)
65    </span><span class=identifier>rename</span><span class=special>(</span><span class=identifier>Point</span><span class=special>.</span><span class=identifier>y</span><span class=special>, </span><span class=string>&quot;Y&quot;</span><span class=special>)
66    </span><span class=identifier>Point</span><span class=special>(</span><span class=string>&quot;int&quot;</span><span class=special>, </span><span class=string>&quot;IPoint&quot;</span><span class=special>)          // </span><span class=identifier>will </span><span class=identifier>have </span><span class=identifier>X </span><span class=keyword>and </span><span class=identifier>Y </span><span class=identifier>as </span><span class=identifier>data </span><span class=identifier>members
67    </span><span class=identifier>Point</span><span class=special>(</span><span class=string>&quot;double&quot;</span><span class=special>, </span><span class=string>&quot;DPoint&quot;</span><span class=special>)       // </span><span class=identifier>also </span><span class=identifier>will </span><span class=identifier>have </span><span class=identifier>X </span><span class=keyword>and </span><span class=identifier>Y </span><span class=identifier>as </span><span class=identifier>data </span><span class=identifier>member
68</span></pre></code>
69<p>
70If you want to change a option of a particular instantiation, you can do so:</p>
71<code><pre>
72    <span class=identifier>Point </span><span class=special>= </span><span class=identifier>Template</span><span class=special>(</span><span class=string>&quot;Point&quot;</span><span class=special>, </span><span class=string>&quot;point.h&quot;</span><span class=special>)
73    </span><span class=identifier>Point</span><span class=special>(</span><span class=string>&quot;int&quot;</span><span class=special>, </span><span class=string>&quot;IPoint&quot;</span><span class=special>)         
74    </span><span class=identifier>d_inst </span><span class=special>= </span><span class=identifier>Point</span><span class=special>(</span><span class=string>&quot;double&quot;</span><span class=special>, </span><span class=string>&quot;DPoint&quot;</span><span class=special>)       
75    </span><span class=identifier>rename</span><span class=special>(</span><span class=identifier>d_inst</span><span class=special>.</span><span class=identifier>x</span><span class=special>, </span><span class=string>&quot;X&quot;</span><span class=special>)           // </span><span class=identifier>only </span><span class=identifier>DPoint </span><span class=identifier>is </span><span class=identifier>affect </span><span class=identifier>by </span><span class=keyword>this </span><span class=identifier>renames</span><span class=special>,
76    </span><span class=identifier>rename</span><span class=special>(</span><span class=identifier>d_inst</span><span class=special>.</span><span class=identifier>y</span><span class=special>, </span><span class=string>&quot;Y&quot;</span><span class=special>)           // </span><span class=identifier>IPoint </span><span class=identifier>stays </span><span class=identifier>intact
77</span></pre></code>
78<table width="80%" border="0" align="center">
79  <tr>
80    <td class="note_box">
81<img src="theme/note.gif"></img> <b>What if my template accepts more than one type?</b>
82<br><br>
83When you want to instantiate a template with more than one type, you can pass
84either a string with the types separated by whitespace, or a list of strings
85(&quot;int double&quot; or [&quot;int&quot;, &quot;double&quot;] would both work).
86    </td>
87  </tr>
88</table>
89<table border="0">
90  <tr>
91    <td width="30"><a href="../index.html"><img src="theme/u_arr.gif" border="0"></a></td>
92    <td width="30"><a href="policies.html"><img src="theme/l_arr.gif" border="0"></a></td>
93    <td width="20"><a href="wrappers.html"><img src="theme/r_arr.gif" border="0"></a></td>
94   </tr>
95</table>
96<br>
97<hr size="1"><p class="copyright">Copyright &copy; 2003 Bruno da Silva de Oliveira<br>Copyright &copy; 2002-2003 Joel de Guzman<br><br>
98<font size="2">Distributed under
99  the Boost Software License, Version 1.0. (See accompanying file
100  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) </font> </p>
101</body>
102</html>
Note: See TracBrowser for help on using the repository browser.