Question

I have the classes

Interface IVehicle
{
    int numberOfWheels;
    bool CanCross(string obstacle);
    // etc
}

class Car : IVehicle
{
    public int numberOfWheels = 4;
    public bool CanCross(string obstacle)
    {
       switch(obstacle) 
       {
          case "river":
              return false;
          case "grass":
              return true;
          // etc
       }
    }
}

class RaceCar: Car
{
    public int numberOfWheels = 4;
    public bool CanCross(string obstacle)
    {
       switch(obstacle) 
       {
          case "river":
              return false;
          case "grass":
              return false;
          // etc
       }
    }
}

And then I have the method:

 public object Foo(IVehicle vehicle, string obstacle)
 {                              
      if(vehicle.CanCross(obstacle)==false)
      {
          if(vehicle is Car)
             return Foo(new RaceCar(), obstacle);
          else if(vehicle is RaceCar)
             return Foo(new OldCar(), obstacle);
         // etc
          else
             return null;
      }

      // implementation

      return someObject;
 }

note that if the vehicle cannot cross the obstacle I recursively call the same method again in order to try with a different vehicle. My question is why if vehicle = SpeedCar then if (vehicle is Car) evaluates to true ? Probably because it inherits from it. How could I check if the vehicle is a SpeedCar but not a Car. I now I could call the ToString() method then do a regex but then if I rename my classes I will break my code…

In other words if the vehicle that I pass cannot cross and it happens to be a Car or SpeedCar I will go into an infinite loop…

Answer 1

How could I check if the vehicle is a SpeedCar but not a Car

vehicle.GetType() == typeof(SpeedCar)