An Object Data Model with Roles

Fibonacci is a strongly typed, object-oricntcd database programming language with a new mechanism to model objects with roles. Traditional object-oriented programming languages do not have the possibility of changing dynamically the type of an object to model the bchaviour of real world entities which change their status over time. This is a severe limitation in the context of a database programming language. Moreover, traditional object-oricntcd languages do not model the fact that the bchaviour of real world entities may depend on the role that they play. WC propose a mechanism to face both problems in the context of a statically strongly typed object-oriented database programming language. We show that the two problems arc strictly related and can be solved without giving up the most useful features of object-oriented programming, namely: inheritance, late binding and encapsulation. Examples will be given referring to the prototype implcmcntalion of’ the language. 1