src/Resource/singleton.h

   1 #ifndef SINGLETON_H
   2 #define SINGLETON_H
   3
   4 /**
   5  * @file singleton.h
   6  * This file contains the Singleton template.
   7  *
   8  * @see Singleton
   9  */
  10
  11 #include "Assert.h"
  12
  13 extern bool g_shutdown; /**< Whether we should allow calls to <code>Free</code>. */
  14
  15 /**
  16  * A template class that implements the Singleton pattern.
  17  * Written on 08-23-2006 by Eran Ifrah.
  18  * Many thanks for allowing the free use of this template!
  19  */
  20 template <class T> class Singleton
  21 {
  22         static T* ms_instance; /**< The one instance of this class. */
  23 public:
  24         /**
  25          * Static method to access the only pointer of this instance.
  26          * @return a pointer to the only instance of this class
  27          */
  28         static T* Get();
  29
  30         /** Release resources. */
  31         static void Free();
  32
  33 protected:
  34         /** Default constructor. */
  35         Singleton();
  36
  37         /** Destructor. */
  38         virtual ~Singleton();
  39 };
  40
  41 template <class T> T* Singleton<T>::ms_instance = 0;
  42
  43 template <class T> Singleton<T>::Singleton()
  44 {
  45 }
  46
  47 template <class T> Singleton<T>::~Singleton()
  48 {
  49 }
  50
  51 template <class T> T* Singleton<T>::Get()
  52 {
  53         Assert(!g_shutdown);
  54
  55         if(!ms_instance)
  56                 ms_instance = new T();
  57         return ms_instance;
  58 }
  59
  60 template <class T> void Singleton<T>::Free()
  61 {
  62         if( ms_instance )
  63         {
  64                 delete ms_instance;
  65                 ms_instance = 0;
  66         }
  67 }
  68
  69 #endif // SINGLETON_H