Introduction course to OOP

During this course at EPFL, we had to realise a couple of projects in Smalltalk. I liked the language very much (better than ADA and the Prolog, Miranda & Lisp which we saw in other courses) and would like to use it one day for a real-world application.

Below is the source of each class. For those of you who never worked with Smalltalk, let me tell you that you never work with files as they look below, but instead always in a nice class-browser.