Reasoning About Multi-Lingual Exception Handling Using RIPLS

Abstract

Building multi-lingual software is a practical necessity. At present, with object-oriented programming the dominant paradigm, it is common to assemble software systems comprising components written in at least two different object-oriented languages. Modern object-oriented languages provide exception handling mechanisms as a means of enriching the signatures of methods with a specification of what to do if the method "fails", i.e., cannot carry out its intended (normal) function for some reason. Indeed, Java and C++ (and many other object-oriented languages, including C#) have remarkably similar exception handling mechanisms. As we demonstrate, however, those exception handling mechanisms do not necessarily interoperate smoothly when used in multi-lingual software systems. We believe that our long-term goal of maximally effortless and error-free multi-lingual programming requires automated tools that are based on solid formal foundations. Toward that end, we have developed a formal language, which we call RIPLS, that can be used to rigorously study properties of multilingual software. In this paper, we demonstrate RIPLS and our approach by using it to study exception handling in multilingual object-oriented systems, and show how use of our methods can identify problems that standard techniques cannot. We then exhibit a correctly-working version of multi-lingual exception-handling and use our methods to confirm its correctness. Finally we discuss how experience with these RIPLS-based methods has informed our designs for automated tools that will implement correctly-working multi-lingual exception handling. This work makes a significant contribution by demonstrating that formal, theoretical foundations can be used to solve practical problems in multi-lingual software development.