OpenMesh
OpenMesh/Core/Utils/SingletonT.hh
00001 /*===========================================================================*\
00002  *                                                                           *
00003  *                               OpenMesh                                    *
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00005  *                           www.openmesh.org                                *
00006  *                                                                           *
00007  *---------------------------------------------------------------------------* 
00008  *  This file is part of OpenMesh.                                           *
00009  *                                                                           *
00010  *  OpenMesh is free software: you can redistribute it and/or modify         * 
00011  *  it under the terms of the GNU Lesser General Public License as           *
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00014  *  following exceptions:                                                    *
00015  *                                                                           *
00016  *  If other files instantiate templates or use macros                       *
00017  *  or inline functions from this file, or you compile this file and         *
00018  *  link it with other files to produce an executable, this file does        *
00019  *  not by itself cause the resulting executable to be covered by the        *
00020  *  GNU Lesser General Public License. This exception does not however       *
00021  *  invalidate any other reasons why the executable file might be            *
00022  *  covered by the GNU Lesser General Public License.                        *
00023  *                                                                           *
00024  *  OpenMesh is distributed in the hope that it will be useful,              *
00025  *  but WITHOUT ANY WARRANTY; without even the implied warranty of           *
00026  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the            *
00027  *  GNU Lesser General Public License for more details.                      *
00028  *                                                                           *
00029  *  You should have received a copy of the GNU LesserGeneral Public          *
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00032  *                                                                           *
00033 \*===========================================================================*/ 
00034 
00035 /*===========================================================================*\
00036  *                                                                           *             
00037  *   $Revision: 362 $                                                         *
00038  *   $Date: 2011-01-26 10:21:12 +0100 (Mi, 26 Jan 2011) $                   *
00039  *                                                                           *
00040 \*===========================================================================*/
00041 
00042 
00043 //=============================================================================
00044 //
00045 //  Implements a simple singleton template
00046 //
00047 //=============================================================================
00048 
00049 
00050 #ifndef __SINGLETON_HH__
00051 #define __SINGLETON_HH__
00052 
00053 
00054 //=== INCLUDES ================================================================
00055 
00056 // OpenMesh
00057 #include <OpenMesh/Core/System/config.h>
00058 
00059 // STL
00060 #include <stdexcept>
00061 #include <iostream>
00062 
00063 
00064 //== NAMESPACES ===============================================================
00065 
00066 
00067 namespace OpenMesh {
00068 
00069 
00070 //=== IMPLEMENTATION ==========================================================
00071 
00072 
00077 template <typename T>
00078 class SingletonT
00079 {
00080 public:
00081 
00088   static T& Instance()
00089   {
00090     if (!pInstance__)
00091     {
00092       // check if singleton alive
00093       if (destroyed__)
00094       {
00095         OnDeadReference();
00096       }
00097       // first time request -> initialize
00098       else
00099       {
00100         Create();
00101       }
00102     }
00103     return *pInstance__;
00104   }
00105 
00106 
00107 private:
00108 
00109   // Disable constructors/assignment to enforce uniqueness
00110   SingletonT();
00111   SingletonT(const SingletonT&);
00112   SingletonT& operator=(const SingletonT&);
00113 
00114   // Create a new singleton and store its pointer
00115   static void Create()
00116   {
00117     static T theInstance;
00118     pInstance__ = &theInstance;
00119   }
00120   
00121   // Will be called if instance is accessed after its lifetime has expired
00122   static void OnDeadReference()
00123   {
00124     throw std::runtime_error("[Singelton error] - Dead reference detected!\n");
00125   }
00126 
00127   virtual ~SingletonT()
00128   {
00129     pInstance__ = 0;
00130     destroyed__ = true;
00131   }
00132   
00133   static T*     pInstance__;
00134   static bool   destroyed__;
00135 };
00136 
00137 
00138 
00139 //=============================================================================
00140 } // namespace OpenMesh
00141 //=============================================================================
00142 #if defined(OM_INCLUDE_TEMPLATES) && !defined(OPENMESH_SINGLETON_C)
00143 #  define OPENMESH_SINGLETON_TEMPLATES
00144 #  include "SingletonT.cc"
00145 #endif
00146 //=============================================================================
00147 #endif // __SINGLETON_HH__
00148 //=============================================================================
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