Programming against an enum in a switch statement, is this your way to do?

Question

Look at the code snippet:

This is what I normally do when coding against an enum. I have a default escape with an InvalidOperationException (I do not use ArgumentExc

Answer 1

There's an alternative to this, which is to use something similar to Java's enums. Private nested types allow for a "stricter" enum where the only "invalid" value available at compile-time is null. Here's an example:

using System;

public abstract class DrivingState
{
    public static readonly DrivingState Neutral = new NeutralState();
    public static readonly DrivingState Drive = new DriveState();
    public static readonly DrivingState Parking = new ParkingState();
    public static readonly DrivingState Reverse = new ReverseState();

    // Only nested classes can derive from this
    private DrivingState() {}

    public abstract void Go();

    private class NeutralState : DrivingState
    {
        public override void Go()
        {
            Console.WriteLine("Not going anywhere...");
        }
    }

    private class DriveState : DrivingState
    {
        public override void Go()
        {
            Console.WriteLine("Cruising...");
        }
    }

    private class ParkingState : DrivingState
    {
        public override void Go()
        {
            Console.WriteLine("Can't drive with the handbrake on...");
        }
    }

    private class ReverseState : DrivingState
    {
        public override void Go()
        {
            Console.WriteLine("Watch out behind me!");
        }
    }
}