Changing abstract method signatures in inherited classes

Question

Imagine I have a class called Engine as an abstract base class. I also have ElectrictEngine and FuelEngine classes which derive from it.

I want to create a method for refueling the engine. Should I do it as an abstract method on the base class level and name it in a generic fasion, such as fillUpEnergy?

The problem is that if I have an electric engine, the number of parameters which the method takes is different from the number of parameters which need to be passed for a Fuel Engine. So, the method's signature is different.

In addition, is there any smart way to use the generic method for both engines but to wrap it in a more specific name? For example: for a fuel Engine, "refuel", and for an electric engine, "chargeBattery"? And at the same time hide the generic method from the user?

Answer 1

In this situation, I would define a generic implementation of your abstract class, such that you get something like this:

public abstract class EngineBase<T>
{
     public abstract void Refuel(T parameters);
}

Then your implementations look like this:

public class ElectricEngine : EngineBase<ElectricParameters>
{
     public override void Refuel(ElectricParameters parameters) { }
}

Alternatively, you can define an interface, and pass a specific implementation to your methods:

public abstract class EngineBase
{
     public abstract void Refuel(IRefuelParameters parameters);
}

Then your implementations look like this:

public class ElectricEngine : EngineBase
{
     public override void Refuel(IRefuelParameters parameters)
     {
          if(!(parameters is ElectricParameters))
              throw ApplicationException("Not the right params!");

          ElectricParameters rightParams = parameters as ElectricParameters;
     }
}