Closing the loop: The influence of code analysis on design

Static code analysis originally concerned the extraction from source code of various properties of a program. Although this kind of reverse engineering approach can uncover errors that are hard to detect in other ways, it is not a very efficient use of resources because of its retrospective nature and the late error detection that results. The SPARK language and its associated Examiner tool took a different approach which emphasises error prevention ("correctness by construction") rather than error detection. Recent work with SPARK has shown that very early application of static analysis can have a beneficial influence on software architectures and designs. The paper describes the use of SPARK to produce designs with demonstrably low coupling and high cohesion.