singleton.h #ifndef SINGLETON_H #define SINGLETON_H template < typename T > class Singleton { public : static T & GetInstance (){ static T instance ; return instance ; } private : Singleton () = default ; ~ Singleton () = default ; Singleton ( const Singleton & ) = delete ; Singleton & operator = ( const Singleton & ) = delete ; Singleton ( Singleton && ) = delete ; Singleton & operator = ( Singleton && ) = delete ; }; #endif // SINGLETON_H How to use? Singleton < LogManager >::GetInstance() . info( this -> metaObject () -> className(), Q_FUNC_INFO , "Initialized" , false , false ); info is my method...