C# Class With Sub Class And Inheritance: setting value in inherited class

Question

I am fairly new to C# so be gentle.
My end goal is to have a few different types of classes for inheritance (example below: Level ). These inherited classes do two things, have .Value property with different setters depending on the class, and a .Action method, unique for every instance so it is an override.

Question: how do i set the .Value property from a method on the class. This is the line of code (line 27) that does not work from the example below. And I don't understand why.

 Potentiometer.Value = Convert.ToDouble(data);

---

// Code taken from https://dotnetfiddle.net/YNJpjf
using System;

namespace Main {
    class Program
    {
        static Device device = new Device();

        static void Main(string[] args)
        {
            device.HandleDataUpdate("50");
        }

    }

    public class Device
    {
        public class Potentiometer : Level
        {
            public override void Action()
            {
                Console.WriteLine("value is at: {0}", this.Value);
            }
        }

        public void HandleDataUpdate(String data)
        {
            Potentiometer.Value = Convert.ToDouble(data);
        }
    }

    public class Level
    {
        private Double thisValue;
        public Double Value
        {
            get => thisValue;
            set
            {
                if (thisValue != value)
                {
                    thisValue = value;
                    Action();
                }
            }
        }

        public virtual void Action()
        {

        }
    }
}

Answer 1

Give Level a protected abstract method OnSetValue , forcing each subclass to override it. Now the setter of Value can call OnSetValue before the value is set:

public class Level {
    private double val;
    public double Value {
        get {
            return val;
        }
        set {
            OnSetValue(value);
            val = value;
        }
    }
    protected abstract void OnSetValue(double val);
    ...
}
public class Potentiometer : Level {
    protected void OnSetValue(double val) {
        ...
    }
}

Answer 2

You need to create an instance of Potentiometer.

https://dotnetfiddle.net/8JQDyO

Answer 3

You're trying to set value of class field, which is impossible, not of object's field. You have to make instance of Potentiometer inside the Device , if you want to do this , you could make method or change code logic.