oasissingleton.h

使用stl技术,(还没看,是听说的)

/******************************************************************************
 * This source file is part of Bad Camel Gaming
 * Copyright (C) 2003  Zephie Greyvenstein
 * See Readme.html for acknowledgements
 *
 * 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 2.1 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
 *****************************************************************************/

/******************************************************************************
 * FILENAME    : oasisSingleton.h
 * DESCRIPTION : Singleton class
 * AUTHOR      : Zephie Greyvenstein
 *****************************************************************************/

/// Avoid double inclusion
#ifndef __SINGLETON_H__
#define __SINGLETON_H__

/// Include common stuff
#include "oasisCommon.h"
/// Include the rest of the needed oasis stuff
#include "oasisException.h"

namespace Oasis {
  /// Singleton class to ensure only one of this class tpye exists
  template < typename T > class singleton {  
  public:
    /// Constructor
    singleton( ) {
      if ( singletonPtr ) {
	oasisError( exception::ET_INTERNAL_ERROR,
		    "This class may only have one instance",
		    "singleton::()" );
      }
      
      singletonPtr = static_cast< T* >( this );
    }
    
    /// Destructor
    ~singleton( ) {
      singletonPtr = 0;
    }
    
    /// Get the singleton for this class
    static T &get( void ) {
      if ( !singletonPtr ) {
	oasisError( exception::ET_INTERNAL_ERROR,
		    "This class does not have an instance",
		    "singleton::get" );
      }
      
      return *singletonPtr;
    }

    /// Get the singleton pointer for this class
    static T *getPtr( void ) {      
      return singletonPtr;
    }
    
  protected:
    /// The singleton handle
    static T *singletonPtr;
  };
};

#endif