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//

// SingletonHolder.h

//

// $Id: //poco/1.3/Foundation/include/Poco/SingletonHolder.h#1 $

//

// Library: Foundation

// Package: Core

// Module:  SingletonHolder

//

// Definition of the SingletonHolder template.

//

// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.

// and Contributors.

//

// Permission is hereby granted, free of charge, to any person or organization

// obtaining a copy of the software and accompanying documentation covered by

// this license (the "Software") to use, reproduce, display, distribute,

// execute, and transmit the Software, and to prepare derivative works of the

// Software, and to permit third-parties to whom the Software is furnished to

// do so, all subject to the following:

// 

// The copyright notices in the Software and this entire statement, including

// the above license grant, this restriction and the following disclaimer,

// must be included in all copies of the Software, in whole or in part, and

// all derivative works of the Software, unless such copies or derivative

// works are solely in the form of machine-executable object code generated by

// a source language processor.

// 

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT

// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE

// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,

// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER

// DEALINGS IN THE SOFTWARE.

//

#ifndef Foundation_SingletonHolder_INCLUDED

#define Foundation_SingletonHolder_INCLUDED

#include "Poco/Foundation.h"

#include "Poco/Mutex.h"

namespace Poco {

template <class S>

class SingletonHolder

        /// This is a helper template class for managing

        /// singleton objects allocated on the heap.

        /// The class ensures proper deletion (including

        /// calling of the destructor) of singleton objects

        /// when the application that created them terminates.

{

public:

        SingletonHolder()

                /// Creates the SingletonHolder.

        {

                _pS = 0;

        }

        ~SingletonHolder()

                /// Destroys the SingletonHolder and the singleton

                /// object that it holds.

        {

                delete _pS;

        }

        S* get()

                /// Returns a pointer to the singleton object

                /// hold by the SingletonHolder. The first call

                /// to get will create the singleton.

        {

                FastMutex::ScopedLock lock(_m);

                if (!_pS) _pS = new S;

                return _pS;

        }

private:

        S* _pS;

        FastMutex _m;

};

} // namespace Poco

#endif // Foundation_SingletonHolder_INCLUDED