public class Sample{

    public void someSampleMethod()
    {
        //assume there is an array called james with 500 elements.
        for (int i = james.length-1; i>=0; i--)
            ((Klass)james[i]).update(this, arg); //how do I write this in ruby?
    }

}

public interface Klass{

    public void update(object o, object arg);
}