TuttleOFX/libraries/tuttle/src/tuttle/common/patterns/StaticSingleton.hpp

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#ifndef StaticSingleton_HPP
#define StaticSingleton_HPP

/**
 * @brief StaticSingleton<ClassStaticSingleton> Can transform a class into static Singleton (by inheriting this class)
 *
 * @par Purpose
 * Forcing (limit) the presence of a single instance of a class
 *
 * @par Usage
 * The class T, to use as static Singleton, must derive from this class (: public StaticSingleton <T>).
 * The macro MAKE_StaticSingleton(T) create necessary elements (including constructors).
 */
template <class T>
class StaticSingleton
{
private:
        static T inst;

private:
        StaticSingleton( const StaticSingleton& ) {}
        StaticSingleton& operator=( const StaticSingleton& ) {}

protected:
        StaticSingleton() {}
        virtual ~StaticSingleton() = 0;

public:
        /**
         * @brief return the unique instance of StaticSingleton<T> class
         * @return T the unique instance of StaticSingleton<T> class
         */
        static T& instance()
        {
                return inst;
        }

};

template <class T>
T StaticSingleton<T>::inst;
template <class T>
StaticSingleton<T>::~StaticSingleton() {}

///macro to implement StaticSingleton. Use it in derived class declaration
#define MAKE_StaticSingleton( Class ) \
        public: \
                friend class StaticSingleton < Class >; \
        private: \
                Class() {} \
                ~Class() {}

#endif