Teaching data abstraction in a beginning Pascal class

Reviewer: Herbert A. Klaeren

The use of abstract data types in the design of software systems is, among software engineers, a generally accepted technique and is surely an important topic in a computer science curriculum. Unfortunately, there are many people from other disciplines, such as civil and electrical engineering, who do participate in some programming classes but never learn even the most basic software engineering principles. Taking into account that these people later on also write some fairly complex programs, it seems to be a good idea to teach them at least the principle of data abstraction in a regular programming class. This paper reports on difficulties encountered in communicating quickly the idea of abstract data types and the motivation for their use to non-computer scientists. The stack and the complex number are identified as abstract data types which naturally arise in the implementation of a calculator program. Assignments for different implementations of these types give the students enough opportunity to realize the benefits of properly using data abstraction.