Showing papers by "Barbara Liskov published in 1978"

A language extension for expressing constraints on data access

Abstract: Controlled sharing of information is needed and desirable for many applications and is supported in operating systems by access control mechanisms. This paper shows how to extend programming languages to provide controlled sharing. The extension permits expression of access constraints on shared data. Access constraints can apply both to simple objects, and to objects that are components of larger objects, such as bank account records in a bank's data base. The constraints are stated declaratively, and can be enforced by static checking similar to type checking. The approach can be used to extend any strongly-typed language, but is particularly suitable for extending languages that support the notion of abstract data types.

Aspects Of Implementing CLU

Abstract: Linguistic mechanisms used in CLU to support 1) structured exception handling, 2) iteration over abstract objects, and 3) parameterized abstractions are briefly reviewed, and methods of realizing these mechanisms are described. The mechanisms discussed support features that are likely to be included in other programming languages, and the implementation methods should be applicable to a wide range of languages.