A Study of Program Evolution Involving Scattered Concerns
Martin P. Robillard, Gail C. Murphy · 2003
Before making a change to a system, software developers typically explore the source code to find and understand the subset relevant to their task. Software changes often involve code addressing different conceptually-related segments of the implementation (concerns), which can be scattered across multiple modules. These scattered concerns make it difficult to reason about the code relevant to a change. We carried out a study to investigate how developers discover and manage scattered concerns during a software evolution task, and the role that structural queries play during the investigation. The task we studied consists of a developer adding a feature to a 65kloc Java code base. The study involved eight subjects: four who were not briefed about scattered concerns, and four who were trained to use a concern-oriented investigation tool. Analysis of the navigation among the different program elements examined by the subjects during the task shows evidence that, independent of whether concernoriented tool support was available, the most successful subjects focused on specific concerns when planning their task, and used a high proportion of structural queries to investigate the code. In addition to the study results, this paper introduces two novel analyses: navigation graphs, which support the analysis of a subject’s behavior when investigating source code, and variant analysis, which is used for evaluating the results of a program evolution task.