C#: Inheritance Problem with List

Question

Let\'s assume this class in C#:

public class LimitedList : List
{
    private int _maxitems = 500;

    public void Add(T value) /* Adding          


        

Answer 1

No - don't use new here; that doesn't give you polymorphism. List isn't intended for inheritance in this way; use Collection and override the Add InsertItem method.

public class LimitedCollection : Collection
{
    private int _maxitems = 500;

    protected override void InsertItem(int index, T item)
    {
        base.InsertItem(index, item);
        TrimData(); /* Delete old data if lenght too long */
    }

    private void TrimData()
    {
        int num = Math.Max(0, base.Count - _maxitems);
        while (num > 0)
        {
            base.RemoveAt(0);
            num--;
        }
    }
}