psingleton.h

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/*
 *   P::Classes - Portable C++ Application Framework
 *   Copyright (C) 2000-2004  Christian Prochnow <cproch@seculogix.de>
 *
 *   This library is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU Lesser General Public
 *   License as published by the Free Software Foundation; either
 *   version 2 of the License, or (at your option) any later version.
 *
 *   This library 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
 *   Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public
 *   License along with this library; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#ifndef _psingleton_h_
#define _psingleton_h_

#include <pclasses/plocktraits.h>

namespace P {


template <typename _T, class _Mutex = VoidMutex>
class Singleton {
  public:
    typedef typename LockTraits<_Mutex>::MutexType MutexType;
    typedef typename LockTraits<_Mutex>::WriteLock WriteLock;

    static _T& instance()
    {
      WriteLock l(_mutex);
      if(!_instance)
        _instance = new _T();

      return *_instance;
    }

  protected:
    Singleton() {}
    ~Singleton() {}
    
  private:
    static MutexType  _mutex;
    static _T*        _instance;
};

template <class _T, class _Mutex>
typename Singleton<_T,_Mutex>::MutexType Singleton<_T,_Mutex>::_mutex;

template <class _T, class _Mutex>
_T* Singleton<_T,_Mutex>::_instance = 0;

}

#endif

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