Interesting twist - this one is in SmallTalk. I found this via one of the students' solutions: http://www.ugrad.cs.jhu.edu/~ericm/projects.html Then there is this one: http://tquark.pha.jhu.edu/~yik/project/oos/assignment/index.html I *think* the latter is also a student project submission, though it may be the professor's solution, I'm not sure. See also http://www.cs.jhu.edu/~scott/oos/ ... this is the professor, but his files are not on public view.