a singleton template class to simplify the implementation of a few classes

src/simulator/simulation-singleton.h

@@ -0,0 +1,89 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2007 INRIA
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation;
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ * Author: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>
+ */
+#ifndef SIMULATION_SINGLETON_H
+#define SIMULATION_SINGLETON_H
+
+namespace ns3 {
+
+/**
+ * This singleton class template ensures that the type
+ * for which we want a singleton has a lifetime bounded
+ * by the simulation lifetime. That it, the underlying
+ * type will be automatically deleted upon a users' call
+ * to Simulator::Destroy.
+ */
+template <typename T>
+class SimulationSingleton
+{
+public:
+  /**
+   * \returns the instance underlying this singleton.
+   *
+   * This instance will be automatically deleted when the
+   * user calls ns3::Simulator::Destroy.
+   */
+  static T *Get (void);
+private:
+  static T **GetObject (void);
+  static void DeleteObject (void);
+};
+
+}//namespace ns3
+
+
+#include "simulator.h"
+
+namespace ns3 {
+
+template <typename T>
+T *
+SimulationSingleton<T>::Get (void)
+{
+  T ** ppobject = GetObject ();
+  return *ppobject;
+}
+
+template <typename T>
+T **
+SimulationSingleton<T>::GetObject (void)
+{
+  static T *pobject = 0;
+  if (pobject == 0)
+    {
+      pobject = new T ();
+      Simulator::ScheduleDestroy (&SimulationSingleton<T>::DeleteObject);
+    }
+  return &pobject;
+}
+
+template <typename T>
+void
+SimulationSingleton<T>::DeleteObject (void)
+{
+  T **ppobject = GetObject ();
+  delete (*ppobject);
+  *ppobject = 0;
+}
+
+} // namespace ns3
+
+
+#endif /* SIMULATION_SINGLETON_H */