C#

public event EventHandler<string> MyText;

protected void OnMyTextChanged()
{
  EventHandler<string> handler = MyText;
  if (handler == null)
  {
    return;
  }
  handler(this, new TextChangedEventArgs(textBox.Text));
}

public class TextChangedEventArgs : EventArgs
{
  public TextChangedEventArgs(string text) : base()
  {
    MyText = text;
  }
  public string MyText { get; private set; }
}

abstract public class MyClass2: MyClass1
{
    public override int f()
    {
        return 0;
    }

    public static void Main()
    {
    }
}

Deborah Palmer McCain wrote:

Should this be simple deduction and logical?

public abstract class Foo
{
    public abstract void Bar();
}

public abstract class Baz : Foo
{
    //Not-necessary to implement Bar() as Baz is also abstract
    public virtual void Quux()
    {
    }

    public virtual void Grault()
    {
    }
}

public class Corge : Foo
{
    public override void Bar()
    {
        //As this is non-abstract it must implement Bar()
    }

    public override void Quux()
    {
        //Overides virtual method
    }

    //Not-necessary to override Grault, but it is possible as per Quux().
}

public override int f()
{
...
}

abstract public class MyClass2

abstract public class MyClass2: MyClass1