As we noted above, Cuis-Smalltalk is a pure object-oriented environment. This means that every single entity you are dealing with is represented as an instance of a class written in Cuis-Smalltalk itself. As a direct consequence, Cuis-Smalltalk is mostly written in itself. This means the entire system is open to you to learn and play with.
What we call system classes are models of fundamental objects. In other programming languages, these would be implemented in that language’s standard library.
In a truly open system, there is no real distinction between system classes and user classes, but it will help us to draw a boundary around the most used objects. Let’s have a brief introduction to some fundamental Smalltalk classes and their most important methods.
In the upper left pane of the Browser, Categories of classes important to start with are:
Collections-Abstract, Collections-Unordered, Collections-Sequenceable, Collections-Arrayed. Related to Array, Dictionary, Set, OrderedCollection and many more. This category includes common accessing, enumeration, mathematical functions, and sorting.