Data-Oriented Exception Handling

摘要

Exception handling mechanisms were added to programming languages to segregatealgorithmic processing from error processing. However, there is no consensus on how to define exceptions. In addition, attaching handlers to control statements clutters source text in much the same way that testing parameters for suitability as inputs for an operation and significance as results does. In this dissertation, we present a definition for exceptions and a set of language features that support our definition by associating exceptions with the operations of a type of handlers with data objects. We call our notation data oriented exception handling to distinguish it from the usual control-oriented versions. We describe the implementation of a pre-processor from our notation to Ada. Case studies of programs indicate that control-oriented exception handling mechanisms are poorly understood and used. Experimental results indicate that data-oriented exception handling can be used to produce programs that are smaller, better structured, and easier to understand and modify. With the exception of pre-processing time, no significant time or space penalty is incurred using data-oriented exception handling.