Began tutorial and examples.

[SVN r21584]

example/node.hpp

@@ -0,0 +1,60 @@
+// Copyright David Abrahams 2004. Use, modification and distribution is
+// subject to the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+#ifndef NODE_DWA2004110_HPP
+# define NODE_DWA2004110_HPP
+
+# include <iostream>
+
+// Polymorphic list node base class
+
+struct node_base
+{
+	node_base() : m_next(0) {}
+
+    virtual ~node_base()
+    {
+        delete m_next;
+    }
+
+    node_base* next() const
+    {
+        return m_next;
+    }
+
+    virtual void print(std::ostream& s) const = 0;
+    virtual void twice() = 0;
+        
+    void append(node_base* p)
+    {
+        if (m_next)
+            m_next->append(p);
+        else
+            m_next = p;
+    }
+    
+ private:
+	node_base* m_next;
+};
+
+inline std::ostream& operator<<(std::ostream& s, node_base const& n)
+{
+    n.print(s);
+    return s;
+}
+
+template <class T>
+struct node : node_base
+{
+    node(T x)
+      : m_value(x)
+    {}
+
+    void print(std::ostream& s) const { s << this->m_value; }
+    void twice() { m_value += m_value; }
+    
+ private:
+    T m_value;
+};
+    
+#endif // NODE_DWA2004110_HPP