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Computer Systems Organization, Software


A common change to object-oriented software is to add a new type of data that is a subtype of some existing type in the program. However, due to message passing unchanged parts of the program may now call operations of the new type. To avoid reverification of unchanged code, such operations should have specifications that are related to the specifications of the appropriate operations in their supertypes. This paper presents a specification technique that uses inheritance of specifications to force the appropriate behavior on the subtype objects. This technique is simple, requires little effort by the specifier, and avoids reverification of unchanged code. We present two notions of such behavioral subtyping, one of which is new. We show how to use these techniques to specify examples in C++.



1996 IEEE. A shorter version and slightly dated version is published in the Proceedings of the 18th International Conference on Software Engineering (ICSE-18), March 25-29, 1996, Berlin, Germany. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works, must be obtained from the IEEE.