Systems Analysis and Synthesis

7.4. Object-oriented Systems

Object-oriented programming builds complex programs from objects. An object comprises a data structure representing its state, and a set of methods that can inspect or change the state. An object is therefore a mini-system, and a method is close to what we have called an event procedure . The following characteristics of object-oriented programming are of interest here:

• Objects are instances of object classes. Every object in a class has a similar set of state variables and the same set of methods.

• Objects communicate by method calls, which are similar to procedure calls. In what follows, Candidate.Enrol(sem,c,s) denotes a method call directed to the Enrol method of object Candidate. The call carries the parameters ...