c++ singleton pattern

Singleton.h

//
//  Singleton.h
//
//  Created by Alexander Sukharev on 05.01.13.
//  Distributed under the MIT software license, see the accompanying
//  file COPYING or http://www.opensource.org/licenses/mit-license.php
//

#ifndef Singleton_h
#define Singleton_h

template<class Class>
class Singleton {
public:
  Singleton(void) {
		if (instance_)
			throw; // or what have you...
		instance_ = (Class*) this;
	}

	static inline Class& instance(void) {
		return *instance_;
	}

	static inline bool exists(void) {
		return instance_ != 0;
	}

	virtual ~Singleton(void) {
		instance_ = 0;
	}

protected:

	static Class* instance_;
};

template<typename Class>
Class* Singleton<Class>::instance_ = 0;

#endif