Abstract

Ownership Types prevent representation exposure - unauthorised access to the encapsulated implementation of an object. Unfortunately, existing ownership type systems are too strict, do not support subtyping, and exclude many important object-oriented idioms, such as iterators, objects with multiple interfaces, and initialisation with pre-existing objects. We develop a more flexible model of containment by abstractly modeling the two sides of object access, that is, which objects an object can access and which objects can access it. Using a variant of Abadi and Cardelli's object calculus as a vehicle, we provide an account of object ownership which supports subtyping and allows more flexible object graph structure.

Citations