Singleton.h

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#ifndef _utl_Singleton_h_
#define _utl_Singleton_h_


namespace utl {

#ifndef OFFLINE_USE_GAMMA_SINGLETON

  template<typename T>
  class Singleton {
  public:
    static
    T&
    GetInstance()
#  ifdef __MAKECINT__
    ;
#  else
    {
      static T instance;
      return instance;
    }
#  endif

  protected:
    // derived class can call ctor and dtor
    Singleton() { }
    ~Singleton() { }

  private:
    // no one should do copies
    Singleton(const Singleton&);
    Singleton& operator=(const Singleton&);
  };

#else

  template<typename T>
  class Singleton {
  public:
    static
    T&
    GetInstance()
    {
      if (!fgInstance)
        fgInstance = new T;
      return *fgInstance;
    }

  protected:
    // derived class can call ctor and dtor
    Singleton() { }
    ~Singleton() { }

  private:
    // no one should do copies
    Singleton(const Singleton&);
    Singleton& operator=(const Singleton&);

    static T* fgInstance = 0;
  };

#endif


  template<class T>
  class LeakingSingleton {
  public:
    static
    T&
    GetInstance()
    {
      static T* const instance = new T;
      return *instance;
    }

  protected:
    // derived class can call ctor and dtor
    LeakingSingleton() { }
    ~LeakingSingleton() { }

  private:
    // no one should do copies
    LeakingSingleton(const LeakingSingleton&);
    LeakingSingleton& operator=(const LeakingSingleton&);
  };

}


#endif