2002-11-19 14:22:58 +00:00
|
|
|
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
|
|
|
|
|
|
<html>
|
|
|
|
|
|
<head>
|
|
|
|
|
|
<title>Boost: enable_shared_from_this.hpp documentation</title>
|
|
|
|
|
|
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
|
|
|
|
|
|
</head>
|
|
|
|
|
|
<body bgcolor="white" style="MARGIN-LEFT: 5%; MARGIN-RIGHT: 5%">
|
|
|
|
|
|
<table border="0" width="100%">
|
|
|
|
|
|
<tr>
|
2005-09-25 21:54:19 +00:00
|
|
|
|
<td width="277"><A href="../../index.htm"> <img src="../../boost.png" alt="boost.png (6897 bytes)" width="277" height="86" border="0"></A>
|
2002-11-19 14:22:58 +00:00
|
|
|
|
</td>
|
2005-09-25 21:54:19 +00:00
|
|
|
|
<td align="center">
|
2002-11-19 14:22:58 +00:00
|
|
|
|
<h1>enable_shared_from_this.hpp</h1>
|
|
|
|
|
|
</td>
|
|
|
|
|
|
</tr>
|
|
|
|
|
|
<tr>
|
|
|
|
|
|
<td colspan="2" height="64"> </td>
|
|
|
|
|
|
</tr>
|
|
|
|
|
|
</table>
|
|
|
|
|
|
<h3><a name="Purpose">Purpose</a></h3>
|
|
|
|
|
|
<p>
|
|
|
|
|
|
The header <STRONG><boost/enable_shared_from_this.hpp></STRONG> defines
|
|
|
|
|
|
the class template <STRONG>enable_shared_from_this</STRONG>. It is used as a
|
|
|
|
|
|
base class that allows a <A href="shared_ptr.htm">shared_ptr</A> to the current
|
|
|
|
|
|
object to be obtained from within a member function.
|
|
|
|
|
|
</p>
|
|
|
|
|
|
<P><STRONG>enable_shared_from_this<T></STRONG> defines two member functions
|
|
|
|
|
|
called <STRONG>shared_from_this</STRONG> that return a <STRONG>shared_ptr<T></STRONG>
|
|
|
|
|
|
and <STRONG>shared_ptr<T const></STRONG>, depending on constness, to <STRONG>this</STRONG>.</P>
|
|
|
|
|
|
<h3><a name="Example">Example</a></h3>
|
|
|
|
|
|
<pre>
|
|
|
|
|
|
class Y: public enable_shared_from_this<Y>
|
|
|
|
|
|
{
|
|
|
|
|
|
public:
|
|
|
|
|
|
|
|
|
|
|
|
shared_ptr<Y> f()
|
|
|
|
|
|
{
|
|
|
|
|
|
return shared_from_this();
|
|
|
|
|
|
}
|
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
int main()
|
|
|
|
|
|
{
|
|
|
|
|
|
shared_ptr<Y> p(new Y);
|
|
|
|
|
|
shared_ptr<Y> q = p->f();
|
|
|
|
|
|
assert(p == q);
|
|
|
|
|
|
assert(!(p < q || q < p)); // p and q must share ownership
|
|
|
|
|
|
}
|
|
|
|
|
|
</pre>
|
|
|
|
|
|
<h3><a name="Synopsis">Synopsis</a></h3>
|
|
|
|
|
|
<pre>
|
|
|
|
|
|
namespace boost
|
|
|
|
|
|
{
|
|
|
|
|
|
|
|
|
|
|
|
template<class T> class enable_shared_from_this
|
|
|
|
|
|
{
|
|
|
|
|
|
public:
|
|
|
|
|
|
|
|
|
|
|
|
shared_ptr<T> shared_from_this();
|
|
|
|
|
|
shared_ptr<T const> shared_from_this() const;
|
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
}
|
|
|
|
|
|
</pre>
|
|
|
|
|
|
<h4>template<class T> shared_ptr<T>
|
|
|
|
|
|
enable_shared_from_this<T>::shared_from_this();</h4>
|
|
|
|
|
|
<h4>template<class T> shared_ptr<T const>
|
|
|
|
|
|
enable_shared_from_this<T>::shared_from_this() const;</h4>
|
|
|
|
|
|
<blockquote>
|
|
|
|
|
|
<p>
|
|
|
|
|
|
<b>Requires:</b> <STRONG>enable_shared_from_this<T></STRONG> must be an
|
|
|
|
|
|
accessible base class of <b>T</b>. <STRONG>*this</STRONG> must be a subobject
|
2003-02-05 12:56:48 +00:00
|
|
|
|
of an instance <STRONG>t</STRONG> of type <STRONG>T</STRONG> . There must exist
|
|
|
|
|
|
at least one <STRONG>shared_ptr</STRONG> instance <STRONG>p</STRONG> that <EM>owns</EM>
|
|
|
|
|
|
<STRONG>t</STRONG>.
|
2002-11-19 14:22:58 +00:00
|
|
|
|
</p>
|
|
|
|
|
|
<p>
|
|
|
|
|
|
<b>Returns:</b> A <b>shared_ptr<T></b> instance <b>r</b> that shares
|
|
|
|
|
|
ownership with <b>p</b>.
|
|
|
|
|
|
</p>
|
|
|
|
|
|
<p>
|
|
|
|
|
|
<b>Postconditions:</b> <tt>r.get() == this</tt>.
|
|
|
|
|
|
</p>
|
|
|
|
|
|
</blockquote>
|
|
|
|
|
|
<p>
|
|
|
|
|
|
<br>
|
2006-11-09 20:24:23 +00:00
|
|
|
|
<small>Copyright <20> 2002, 2003 by Peter Dimov. Distributed under the Boost Software License, Version
|
|
|
|
|
|
1.0. See accompanying file <A href="../../LICENSE_1_0.txt">LICENSE_1_0.txt</A> or
|
|
|
|
|
|
copy at <A href="http://www.boost.org/LICENSE_1_0.txt">http://www.boost.org/LICENSE_1_0.txt</A>.</small></p>
|
2002-11-19 14:22:58 +00:00
|
|
|
|
</body>
|
|
|
|
|
|
</html>
|
