Guarded methods vs. inheritance anomaly

Abstract

The term Inheritance Anomaly has been introduced into Object-Oriented Concurrent Programming (OOCP). It has also been shown how different kinds of synchronization mechanisms fall into one of the three anomalies. Guarded Methods are shown to be an inadequate tool to solve either History-only Sensitive Anomaly or Modification of Acceptable States. This paper argues that any of the anomalies can be solved by Guarded Methods when a suitable semantics is found for it. The main contribution of the paper is the exposition that the concept of Guarded Methods, provided Guarded Methods are interpreted as Conditional Critical Regions, is an adequate language tool for expressing synchronization constraints in OOCP. Guarded Method based solutions are given for the above mentioned two cases of anomalies.