40 lines
774 B
C
40 lines
774 B
C
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#pragma once
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template< typename T >
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struct Singleton
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{
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typedef T value_type;
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typedef Singleton self_type;
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private:// not to be implemented
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Singleton(const self_type&){}
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self_type& operator = (const self_type&){}
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Singleton(){}
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friend T;
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private:// this struct promises thread safty
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struct creator
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{
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creator()
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{ // ensure that instance() called before main() starts
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self_type::instance();
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}
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inline void null_action() const
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{
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//empty
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}
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};
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static creator creator_;
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public:
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static value_type& instance()
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{ // the object to be returned
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static value_type instance_;
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// force the initialization of creator_
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creator_.null_action();
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return instance_;
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}
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};
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template<typename T>
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typename Singleton<T>::creator Singleton<T>::creator_;
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