A Parameterized Type System for Simple Loose Ownership Domains

Jan Schäfer, TU Kaiserslautern, Germany
Arnd Poetzsch-Heffter, TU Kaiserslautern, Germany

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Abstract

Ownership Domains generalize ownership types. They support programming patterns such as iterators that are not possible with ordinary ownership types. However, they are still too restrictive for cases in which an object X wants to access the public domains of an arbitrary number of other objects, which often happens in observer scenarios. To overcome this restriction, we develop so-called loose domains which abstract over several precise domains. Similar to the relation between supertypes and subtypes, we get a relation between loose and precise domains. In addition, we simplify ownership domains by reducing the number of domains per object to two and hard-wiring the access permissions between domains. We formalize the resulting type system for an OO core language and prove type soundness and a fundamental accessibility property.

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About the authors

Jan Schäfer is a PhD student and research assistant at the Software Technology Group at the TU Kaiserslautern, Germany. His research is supported by the Deutsche Forschungsgemeinschaft (German Research Foundation). Contact him at jschaefer@informatik.uni-kl.de.
See also http://softech.informatik.uni-kl.de/˜janschaefer.

Arnd Poetzsch-Heffter is a professor at the Computer Science Department of the TU Kaiserslautern, Germany. He is heading the Software Technology Group. He can be reached at poetzsch@informatik.uni-kl.de. See also http://softech.informatik.uni-kl.de/.

Cite this article as follows:Jan Schäfer und Arnd Poetzsch-Heffter:"A Parameterized Type System for Simple Loose Ownership Domains", in Journal of Object Technology, vol. 6, no. 5, Special Issue ECOOP 2007, pp. 71-100 http://www.jot.fm/issues/issue_2007_06/article3