tutorial added

[SVN r15817]
2026-01-26 06:42:27 +00:00 · 2002-10-09 05:03:22 +00:00
parent 4fd20185e9
commit e49e0d2705
39 changed files with 3237 additions and 3 deletions
--- a/doc/tutorial/doc/constructors.html
+++ b/doc/tutorial/doc/constructors.html
@@ -0,0 +1,102 @@
+<html>
+<head>
+<!-- Generated by the Spirit (http://spirit.sf.net) QuickDoc -->
+<title>Constructors</title>
+<link rel="stylesheet" href="theme/style.css" type="text/css">
+<link rel="prev" href="exposing_classes.html">
+<link rel="next" href="class_data_members.html">
+</head>
+<body>
+<table width="100%" height="48" border="0" cellspacing="2">
+  <tr>
+    <td><img src="theme/c%2B%2Bboost.gif">
+    </td>
+    <td width="85%">
+      <font size="6" face="Verdana, Arial, Helvetica, sans-serif"><b>Constructors</b></font>
+    </td>
+  </tr>
+</table>
+<br>
+<table border="0">
+  <tr>
+    <td width="30"><a href="../index.html"><img src="theme/u_arr.gif" border="0"></a></td>
+    <td width="30"><a href="exposing_classes.html"><img src="theme/l_arr.gif" border="0"></a></td>
+    <td width="20"><a href="class_data_members.html"><img src="theme/r_arr.gif" border="0"></a></td>
+   </tr>
+</table>
+<p>
+Our previous example didn't have any explicit constructors.
+Since <tt>World</tt> is declared as a plain struct, it has an implicit default
+constructor. Boost.Python exposes the default constructor by default,
+which is why we were able to write</p>
+<code><pre>
+    <span class=special>&gt;&gt;&gt; </span><span class=identifier>planet </span><span class=special>= </span><span class=identifier>hello</span><span class=special>.</span><span class=identifier>World</span><span class=special>()
+</span></pre></code>
+<p>
+We may wish to wrap a class with a non-default constructor. Let us
+build on our previous example:</p>
+<code><pre>
+    <span class=keyword>struct </span><span class=identifier>World
+    </span><span class=special>{
+        </span><span class=identifier>World</span><span class=special>(</span><span class=identifier>std</span><span class=special>::</span><span class=identifier>string </span><span class=identifier>msg</span><span class=special>): </span><span class=identifier>msg</span><span class=special>(</span><span class=identifier>msg</span><span class=special>) </span><span class=special>{} </span><span class=comment>// added constructor
+        </span><span class=keyword>void </span><span class=identifier>set</span><span class=special>(</span><span class=identifier>std</span><span class=special>::</span><span class=identifier>string </span><span class=identifier>msg</span><span class=special>) </span><span class=special>{ </span><span class=keyword>this</span><span class=special>-&gt;</span><span class=identifier>msg </span><span class=special>= </span><span class=identifier>msg</span><span class=special>; </span><span class=special>}
+        </span><span class=identifier>std</span><span class=special>::</span><span class=identifier>string </span><span class=identifier>greet</span><span class=special>() </span><span class=special>{ </span><span class=keyword>return </span><span class=identifier>msg</span><span class=special>; </span><span class=special>}
+        </span><span class=identifier>std</span><span class=special>::</span><span class=identifier>string </span><span class=identifier>msg</span><span class=special>;
+    </span><span class=special>};
+</span></pre></code>
+<p>
+This time <tt>World</tt> has no default constructor; our previous
+wrapping code would fail to compile when the library tried to expose
+it. We have to tell <tt>class_&lt;World&gt;</tt> about the constructor we want to
+expose instead.</p>
+<code><pre>
+    <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>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=identifier>BOOST_PYTHON_MODULE</span><span class=special>(</span><span class=identifier>hello</span><span class=special>)
+    </span><span class=special>{
+        </span><span class=identifier>class_</span><span class=special>&lt;</span><span class=identifier>World</span><span class=special>&gt;(</span><span class=string>&quot;World&quot;</span><span class=special>, </span><span class=identifier>init</span><span class=special>&lt;</span><span class=identifier>std</span><span class=special>::</span><span class=identifier>string</span><span class=special>&gt;())
+            </span><span class=special>.</span><span class=identifier>def</span><span class=special>(</span><span class=string>&quot;greet&quot;</span><span class=special>, </span><span class=special>&amp;</span><span class=identifier>World</span><span class=special>::</span><span class=identifier>greet</span><span class=special>)
+            </span><span class=special>.</span><span class=identifier>def</span><span class=special>(</span><span class=string>&quot;set&quot;</span><span class=special>, </span><span class=special>&amp;</span><span class=identifier>World</span><span class=special>::</span><span class=identifier>set</span><span class=special>)
+        </span><span class=special>;
+    </span><span class=special>}
+</span></pre></code>
+<p>
+<tt>init&lt;std::string&gt;()</tt> exposes the constructor taking in a
+<tt>std::string</tt> (in Python, constructors are spelled
+&quot;<tt>__init__(...)</tt>&quot;).</p>
+<p>
+We can expose additional constructors by passing more <tt>init&lt;...&gt;</tt>s to
+the <tt>def()</tt> member function. Say for example we have another World
+constructor taking in two doubles:</p>
+<code><pre>
+    <span class=identifier>class_</span><span class=special>&lt;</span><span class=identifier>World</span><span class=special>&gt;(</span><span class=string>&quot;World&quot;</span><span class=special>, </span><span class=identifier>init</span><span class=special>&lt;</span><span class=identifier>std</span><span class=special>::</span><span class=identifier>string</span><span class=special>&gt;())
+        </span><span class=special>.</span><span class=identifier>def</span><span class=special>(</span><span class=identifier>init</span><span class=special>&lt;</span><span class=keyword>double</span><span class=special>, </span><span class=keyword>double</span><span class=special>&gt;())
+        </span><span class=special>.</span><span class=identifier>def</span><span class=special>(</span><span class=string>&quot;greet&quot;</span><span class=special>, </span><span class=special>&amp;</span><span class=identifier>World</span><span class=special>::</span><span class=identifier>greet</span><span class=special>)
+        </span><span class=special>.</span><span class=identifier>def</span><span class=special>(</span><span class=string>&quot;set&quot;</span><span class=special>, </span><span class=special>&amp;</span><span class=identifier>World</span><span class=special>::</span><span class=identifier>set</span><span class=special>)
+    </span><span class=special>;
+</span></pre></code>
+<p>
+On the other hand, if we do not wish to expose any constructors at
+all, we may use <tt>no_init</tt> instead:</p>
+<code><pre>
+    <span class=identifier>class_</span><span class=special>&lt;</span><span class=identifier>Abstract</span><span class=special>&gt;(</span><span class=string>&quot;Abstract&quot;</span><span class=special>, </span><span class=identifier>no_init</span><span class=special>)
+</span></pre></code>
+<p>
+This actually adds an <tt>__init__</tt> method which always raises a
+Python RuntimeError exception.</p>
+<table border="0">
+  <tr>
+    <td width="30"><a href="../index.html"><img src="theme/u_arr.gif" border="0"></a></td>
+    <td width="30"><a href="exposing_classes.html"><img src="theme/l_arr.gif" border="0"></a></td>
+    <td width="20"><a href="class_data_members.html"><img src="theme/r_arr.gif" border="0"></a></td>
+   </tr>
+</table>
+<br>
+<hr size="1"><p class="copyright">Copyright &copy; 2002 David Abrahams<br>Copyright &copy; 2002 Joel de Guzman<br><br>
+<font size="2">Permission to copy, use, modify, sell and distribute this document
+ is granted provided this copyright notice appears in all copies. This document
+ is provided &quot;as is&quot; without express or implied warranty, and with
+ no claim as to its suitability for any purpose. </font> </p>
+</body>
+</html>