PostgreSQL/libpqxx Class Generator

/***************************************************************************
 Singleton.h - Implementation of the Singleton design pattern.

 begin     : August 2006
 copyright : (C) 2006 by Phil Cairns
 email     : oti169@hotmail.com
 $Id: Singleton.h 2080 2006-08-18 01:53:19Z phil $

 This code may be used in compiled form in any way you desire (including
 commercial use). The code may be redistributed unmodified by any means
 providing it is not sold for profit without the authors written consent,
 and providing that this notice and the authors name and all copyright
 notices remains intact.

 This software is provided "as is" without express or implied warranty. Use
 it at your own risk!
 ***************************************************************************/

#pragma once

namespace Pagaros
{
	template <typename TYPE> 
	class Singleton
	{
	public:
		/// Global access point to the Singleton.
		static TYPE& instance(void)
		{
			Singleton<TYPE>& singleton = Singleton<TYPE>::instance_i();

			if (singleton._instance == 0)
			{
				singleton._instance = new TYPE;
			}

			return *singleton._instance;
		}

		/// Explicitly delete the Singleton instance.
		static void close(void)
		{
			Singleton<TYPE>& singleton = Singleton<TYPE>::instance_i();
			if (singleton._instance) 
			{
				delete singleton._instance;
			}
		}

	protected:
		/// Contained instance.
		TYPE* _instance;

		/// Get pointer to the Singleton instance.
		static Singleton<TYPE> &instance_i (void)
		{
			static Singleton<TYPE> _singleton;
			return _singleton;
		}
	};
};