This paper describes the author’s Ada package of elementary mathematical functions, emphasizing its error handling features. An ERROR_HANDLER package provides error message printing, traceback lists, and controlled exception propagation. The specifications for the packages described are given, and an example program listing and its output demonstrate the concepts.

The paper explains several important guidelines for Ada programming and gives examples of good error handling techniques. Ada provides capabilities that are not available in other languages, and Ada students can benefit by seeing them used effectively.

Unfortunately, the paper is marred by a number of troublesome errors. The word instantiation, a central Ada concept, is misspelled throughout. The example listings contain typographical errors that will confuse an Ada student. Statements about the runtime cost of instantiation and the optimized linking of separate subunits are incorrect. There are allusions to additional complications that must be dealt with if Ada tasks are used, but these are not identified or explained.

The author describes a deficiency in the error handling capabilities of one vendor’s Ada compiler. However, the release of the compiler described is several years out of date, and the complaint does not apply to later releases. The author does not point this out.

An evaluation of this paper must be mixed. It is good because it addresses an important issue and explains it fairly well. However, it contains several errors that reduce its value for promoting a sound understanding of Ada. With a few deleted sentences and hand-written corrections, this could serve as a useful classroom handout.

In general, this paper is not up to the standards for accuracy and completeness found in other Ada publications. It should have been reviewed and revised prior to publication.