Report Number: CS-TR-80-789
Institution: Stanford University, Department of Computer Science
Title: ADA exceptions: specification and proof techniques
Author: Luckham, David C.
Author: Polak, Wolfgang
Date: February 1980
Abstract: A method of documenting exception propagation and handling in Ada programs is proposed. Exception propagation declarations are introduced as a new component of Ada specifications. This permits documentation of those exceptions that can be propagated by a subprogram. Exception handlers are documented by entry assertions. Axioms and proof rules for Ada exceptions are given. These rules are simple extensions of previous rules for Pascal and define an axiomatic semantics of Ada exceptions. As a result, Ada programs specified according to the method can be analysed by formal proof techniques for consistency with their specifications, even if they employ exception propagation and handling to achieve required results (i.e. non-error situations). Example verifications are given.