Static Class Elements for Object-Z

Static variables and methods are part of almost every modern object-oriented programming language. Static elements are for instance indispensable for certain kinds of design patterns applied during programming. Object-oriented specification formalisms on the other hand lack such concepts. This can prevent writing formal specifications close to the actual implementation, and can thus hamper a refinement-based stepwise development. In this paper, we extend the state-based object-oriented specification language Object-Z with a concept for static class elements. We furthermore show how refinement can introduce static elements into a specification.