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template< class Vehicle > class ElectricEngine { };
template< class Vehicle > class GasEngine { };
 
// Best way
template< template<class> class Engine > class Car   : public Engine<Car>   { };
template< template<class> class Engine > class Plane : public Engine<Plane> { };
 
// Redundant way
class ElectricCarEngine : public ElectricEngine<ElectricCarEngine> {};
class GasCarEngine : public GasEngine<GasCarEngine> {};
class ElectricPlaneEngine : public ElectricEngine<ElectricPlaneEngine> {};
class GasPlaneEngine : public GasEngine<GasPlaneEngine> {};
 
// This does not compile
// template <typename Base>
// class CarEngineInterface : public Base<CarEngineInterface<Base> > {};
 
int main(int argc, char **argv) {
 
	Car<ElectricEngine> myTesla;
	Plane<GasEngine>    myMooney;
 
 
	ElectricCarEngine ec;
 
 
  return 0;
}

prog.cpp:5:73: error: type/value mismatch at argument 1 in template parameter list for ‘template<class> class Engine’
 template< template<class> class Engine > class Car   : public Engine<Car>   { };
                                                                         ^
prog.cpp:5:73: error:   expected a type, got ‘Car’
prog.cpp:6:75: error: type/value mismatch at argument 1 in template parameter list for ‘template<class> class Engine’
 template< template<class> class Engine > class Plane : public Engine<Plane> { };
                                                                           ^
prog.cpp:6:75: error:   expected a type, got ‘Plane’
prog.cpp: In function ‘int main(int, char**)’:
prog.cpp:20:22: warning: unused variable ‘myTesla’ [-Wunused-variable]
  Car<ElectricEngine> myTesla;
                      ^
prog.cpp:21:22: warning: unused variable ‘myMooney’ [-Wunused-variable]
  Plane<GasEngine>    myMooney;
                      ^
prog.cpp:24:20: warning: unused variable ‘ec’ [-Wunused-variable]
  ElectricCarEngine ec;
                    ^

Standard output is empty