Diamond Inheritance and Attribute Types in Timor

Abstract

In Timor multiple inheritance of methods from a common abstract ancestor (e.g. Collection) and of separate "parts" (possibly repeatedly) from distinct supertypes (e.g. a Radio, a Cassette Player) are handled in different ways. The paper shows that neithertechnique is suitable for cases where a common concrete ancestor (e.g. Person) is specialised in different subtypes (e.g. as a Student, an Employee) and then brought together in a new subtype, possibly with repeated inheritance (e.g. a Doubly Employed Student). For such cases a new kind of type ("attribute types") is proposed, which provides an alternative programming paradigm to inheritance, based on the idea of adjectives and their use in noun phrases in natural languages.