A Language Extension for Controlling Access to Shared Data

Controlled sharing of information is needed for many applications. Access-control mechanisms exist in operating systems to provide such controlled sharing. However, programming languages currently do not support such a facility. This paper illustrates how an access-control facility could be incorporated in a programming language. The mechanism described is suitable for incorporation in object-oriented languages that permit the definition of abstract data types, and is defmed in a way that enables compile-time checking of access control.