Views on Edits to Variational Software

Software systems are subject to frequent changes, for example to fix bugs or meet new customer requirements. In variational software systems, developers are confronted with the complexity of evolution and configurability on a daily basis; essentially handling changes to many distinct software variants simultaneously. To reduce the complexity of configurability for developers, filtered or projectional editing was introduced: By providing a partial or complete configuration, developers can interact with a simpler view of the variational system that shows only artifacts belonging to that configuration. Yet, such views are available for individual revisions only but not for edits performed across revisions. To reduce the complexity of evolution in variational software for developers, we extend the concept of views to edits. We formulate a correctness criterion for views on edits and introduce two correct operators for view generation, one operator suitable for formal reasoning, and a runtime optimized operator. In an empirical study, we demonstrate the feasibility of our operators by applying them to the change histories of 44 open-source software systems.