You are on the right path, dear author, but you are still not at the point of understanding debugging. One huge part of debugging is avoiding bugs, and because

You are on the right path, dear author, but you are still not at the point of understanding debugging. One huge part of debugging is avoiding bugs, and because this is often done poorly by the average coder, the next big part is understanding what a piece of code does and specify what it should do. Before you can fix a bug, you need to know what's wrong, not just where it happens. Also, always using inheritance is bad, but so is never using inheritance. (Does that need explanation?)