c++ - Is this standard way to derive from singleton class? -

my base class singleton having protected c'tor. now, can derive class cannot create instance of base class inside functions of derived class. expected behavior per design. know correct c++ standards or compiler specific behavior? (so shouldn't face issues if want port code in future)

class singleton { protected:     singleton() {}  public:     singleton * getinstance()     {         static singleton* instancecreated = null ;          if (!instancecreated)             instancecreated = new singleton ;          return instancecreated ;     } };  class deringlton : public singleton { public:     deringlton()     {         singleton * psing ;         // psing = new singlton ; // cannot create object of singlton                                    // (despite class derived singlton)     } }; 

if have make singleton (which should avoid) instance and(!) declaration singleton. use template have 'generic' one, inheritance no good.