A View Extension to an Object-Oriented Type System

Many languages provide support for describing composite and other user-defined types which in turn depend upon built-in types. A built-in or primitive type is typically composed of a data structure, a set of operations and a view or concrete external representation for that data structure. User-defined types differ from primitive types in that they are typically composed of a data structure and a set of operations only. This paper describes a view model which is an integral part of an object-oriented development language named POOL (Persistent Object-Oriented Language). The language provides a facility for defining multiple and complex views of a user-defined type as an integral part of a type definition. These view definitions are used to enable values of user-defined types to be manipulated directly, for example, during marshalling and input/output operations. This paper also addresses the view inheritance problem associated with user-defined views, and also discusses a type inference strategy adopted for inferring types from values of user-defined types.