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SingletonT.hh
1 /*===========================================================================*\
2 * *
3 * OpenMesh *
4 * Copyright (C) 2001-2012 by Computer Graphics Group, RWTH Aachen *
5 * www.openmesh.org *
6 * *
7 *---------------------------------------------------------------------------*
8 * This file is part of OpenMesh. *
9 * *
10 * OpenMesh is free software: you can redistribute it and/or modify *
11 * it under the terms of the GNU Lesser General Public License as *
12 * published by the Free Software Foundation, either version 3 of *
13 * the License, or (at your option) any later version with the *
14 * following exceptions: *
15 * *
16 * If other files instantiate templates or use macros *
17 * or inline functions from this file, or you compile this file and *
18 * link it with other files to produce an executable, this file does *
19 * not by itself cause the resulting executable to be covered by the *
20 * GNU Lesser General Public License. This exception does not however *
21 * invalidate any other reasons why the executable file might be *
22 * covered by the GNU Lesser General Public License. *
23 * *
24 * OpenMesh is distributed in the hope that it will be useful, *
25 * but WITHOUT ANY WARRANTY; without even the implied warranty of *
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27 * GNU Lesser General Public License for more details. *
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33 \*===========================================================================*/
34
35 /*===========================================================================*\
36 * *
37 * $Revision: 736 $ *
38 * $Date: 2012-10-08 09:30:49 +0200 (Mo, 08. Okt 2012) $ *
39 * *
40 \*===========================================================================*/
41
42
43 //=============================================================================
44 //
45 // Implements a simple singleton template
46 //
47 //=============================================================================
48
49
50 #ifndef __SINGLETON_HH__
51 #define __SINGLETON_HH__
52
53
54 //=== INCLUDES ================================================================
55
56 // OpenMesh
57 #include <OpenMesh/Core/System/config.h>
58
59 // STL
60 #include <stdexcept>
61 #include <iostream>
62
63
64 //== NAMESPACES ===============================================================
65
66
67 namespace OpenMesh {
68
69
70 //=== IMPLEMENTATION ==========================================================
71
72
77 template <typename T>
78 class SingletonT
79 {
80 public:
81
88 static T& Instance()
89 {
90 if (!pInstance__)
91 {
92 // check if singleton alive
93 if (destroyed__)
94 {
95 OnDeadReference();
96 }
97 // first time request -> initialize
98 else
99 {
100 Create();
101 }
102 }
103 return *pInstance__;
104 }
105
106
107 private:
108
109 // Disable constructors/assignment to enforce uniqueness
110 SingletonT();
111 SingletonT(const SingletonT&);
112 SingletonT& operator=(const SingletonT&);
113
114 // Create a new singleton and store its pointer
115 static void Create()
116 {
117 static T theInstance;
118 pInstance__ = &theInstance;
119 }
120
121 // Will be called if instance is accessed after its lifetime has expired
122 static void OnDeadReference()
123 {
124 throw std::runtime_error("[Singelton error] - Dead reference detected!\n");
125 }
126
127 virtual ~SingletonT()
128 {
129 pInstance__ = 0;
130 destroyed__ = true;
131 }
132
133 static T* pInstance__;
134 static bool destroyed__;
135 };
136
137
138
139 //=============================================================================
140 } // namespace OpenMesh
141 //=============================================================================
142 #if defined(OM_INCLUDE_TEMPLATES) && !defined(OPENMESH_SINGLETON_C)
143 # define OPENMESH_SINGLETON_TEMPLATES
144 # include "SingletonT.cc"
145 #endif
146 //=============================================================================
147 #endif // __SINGLETON_HH__
148 //=============================================================================