How do I use composition with inheritance?

Question

I\'m going to try to ask my question in the context of a simple example...

Let\'s say I have an abstract base class Car. Car has-a basic Engine object. I have a method

Answer 1

I think this would work.

public class Car
{
    private Engine engine;
    public virtual Engine CarEngine
    {
        get { return engine;}
    }

    public StartEngine()
    {
         CarEngine.Start();
    }
}

public class Engine
{
     public virtual void Start()
     {
         Console.Writeline("Vroom");
     }
} 

public class TurboEngine : Engine
{
    public override void Start()
    {
        Console.Writeline("Vroom pSHHHHHHH");
    }    

    // TurboEngine Only method
    public double BoostPressure()
    {
    }
}

public class Ferrari : Car
{
    private TurboEngine engine;
    public override Engine CarEngine
    {
         return engine;
    }
}

Ferrari = car new Ferrari();
// Will call Start on TurboEngine()
car.StartEngine();
// Upcast to get TurboEngine stuff
Console.WriteLine(car.CarEngine as TurboEngine).BoostPressure();