source: downloads/ogre/OgreMain/include/OgreSingleton.h @ 17

/*
-----------------------------------------------------------------------------
This source file is part of OGRE
    (Object-oriented Graphics Rendering Engine)
For the latest info, see http://www.ogre3d.org/

Copyright (c) 2000-2006 Torus Knot Software Ltd
Also see acknowledgements in Readme.html

This program 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 program 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 program; if not, write to the Free Software Foundation, Inc., 59 Temple
Place - Suite 330, Boston, MA 02111-1307, USA, or go to
http://www.gnu.org/copyleft/lesser.txt.

You may alternatively use this source under the terms of a specific version of
the OGRE Unrestricted License provided you have obtained such a license from
Torus Knot Software Ltd.
-----------------------------------------------------------------------------
*/
/* Original version Copyright (C) Scott Bilas, 2000.
 * All rights reserved worldwide.
 *
 * This software is provided "as is" without express or implied
 * warranties. You may freely copy and compile this source into
 * applications you distribute provided that the copyright text
 * below is included in the resulting source code, for example:
 * "Portions Copyright (C) Scott Bilas, 2000"
 */
#ifndef _SINGLETON_H__
#define _SINGLETON_H__

// Added by Steve Streeting for Ogre
#include "OgrePrerequisites.h"

#if OGRE_COMPILER == OGRE_COMPILER_MSVC
// Turn off warnings generated by this singleton implementation
#   pragma warning (disable : 4311)
#   pragma warning (disable : 4312)
#endif

#if defined ( OGRE_GCC_VISIBILITY )
#   pragma GCC visibility push(default)
#endif
namespace Ogre {
// End SJS additions
    /** Template class for creating single-instance global classes.
    */
    template <typename T> class Singleton
    {
    protected:

        static T* ms_Singleton;

    public:
        Singleton( void )
        {
            assert( !ms_Singleton );
#if defined( _MSC_VER ) && _MSC_VER < 1200       
            int offset = (int)(T*)1 - (int)(Singleton <T>*)(T*)1;
            ms_Singleton = (T*)((int)this + offset);
#else
            ms_Singleton = static_cast< T* >( this );
#endif
        }
        ~Singleton( void )
            {  assert( ms_Singleton );  ms_Singleton = 0;  }
        static T& getSingleton( void )
                {       assert( ms_Singleton );  return ( *ms_Singleton ); }
        static T* getSingletonPtr( void )
                { return ms_Singleton; }
    };
}
#if defined ( OGRE_GCC_VISIBILITY )
#   pragma GCC visibility pop
#endif
#endif