* This is also useful.

src/boost/enable_shared_from_this.hpp

@@ -0,0 +1,68 @@
+#ifndef BOOST_ENABLE_SHARED_FROM_THIS_HPP_INCLUDED
+#define BOOST_ENABLE_SHARED_FROM_THIS_HPP_INCLUDED
+
+//
+//  enable_shared_from_this.hpp
+//
+//  Copyright (c) 2002 Peter Dimov
+//
+//  Permission to copy, use, modify, sell and distribute this software
+//  is granted provided this copyright notice appears in all copies.
+//  This software is provided "as is" without express or implied
+//  warranty, and with no claim as to its suitability for any purpose.
+//
+//  http://www.boost.org/libs/smart_ptr/enable_shared_from_this.html
+//
+
+#include <boost/weak_ptr.hpp>
+#include <boost/shared_ptr.hpp>
+#include <boost/assert.hpp>
+//#include <boost/config.hpp>
+
+namespace boost
+{
+
+template<class T> class enable_shared_from_this
+{
+protected:
+
+    enable_shared_from_this()
+    {
+    }
+
+    enable_shared_from_this(enable_shared_from_this const &)
+    {
+    }
+
+    enable_shared_from_this & operator=(enable_shared_from_this const &)
+    {
+        return *this;
+    }
+
+    ~enable_shared_from_this()
+    {
+    }
+
+public:
+
+    shared_ptr<T> shared_from_this()
+    {
+        shared_ptr<T> p(_internal_weak_this);
+        BOOST_ASSERT(p.get() == this);
+        return p;
+    }
+
+    shared_ptr<T const> shared_from_this() const
+    {
+        shared_ptr<T const> p(_internal_weak_this);
+        BOOST_ASSERT(p.get() == this);
+        return p;
+    }
+
+    typedef T _internal_element_type; // for bcc 5.5.1
+    weak_ptr<_internal_element_type> _internal_weak_this;
+};
+
+} // namespace boost
+
+#endif  // #ifndef BOOST_ENABLE_SHARED_FROM_THIS_HPP_INCLUDED