In an object-oriented language, a derived class may declare a method with the same signature as a method in the base class. The meaning of the re-declaration depends on the language. Most commonly, the new declaration overrides the base declaration, perhaps completely replacing it, or perhaps using super to invoke the old implementation. Another possibility is that the base class always controls the method implementation, and the new declaration merely augments the method in the case that the base method calls inner. Each possibility has advantages and disadvantages. In this paper, we explain why programmers need both kinds of method redeclaration, and we present a language that integrates them. We also present a formal semantics for the new language, and we describe an implementation for MzScheme.

To protect MITRE's unclassified computing resources from unauthorized use, MITRE maintains a network firewall between the MITRE corporate network and the Internet, and limits dial-in to three modem pools. The firewall limits Internet connectivity to a small set of computer systems called boundary hosts. The boundary hosts and the modem pools use a smartcard-based user authentication scheme to ensure that only authorized MITRE employees can gain access to the corporate network. The combination of firewall, boundary hosts, and modem pools is known as the MITRE security perimeter. The paper describes the design of the security perimeter and the integration of the smartcard system into the boundary hosts and modem pools.>