Question

This is C# related, but actually the question is quite generic.

Let’s say that I have a base class

abstract class Base {
    protected List<string> MyList = new List<string>();
    protected abstract void FillMyList();
}

class Derived : Base {
    protected void FillMyList() {
        MyList.Add("test");
        MyList.Add("test2");
    }
}

This is ok, the derived class fills the MyList defined in the base class.

However, besides the abstract method name (FillMyList) – that hints that you actually HAVE to fill MyList – there is no clue to what this method is supposed to mean.

Is there a better way to enforce or (better) suggest strongly that you will have to fill MyList when you are inheriting from Base?
Maybe having the FillMyList declared as:

protected abstract void FillMyList(List<string> listToFill);

What do you suggest?

Answer 1

You can convert MyList to abstract property with getter, which derived must implementing

public abstract class Base
{
    public abstract List<int> List { get; }
}

public class Derived : Base
{
    #region Overrides of Base

    public override List<int> List
    {
        get { return new List<int> {1, 2, 3}; }
    }

    #endregion
}