Feature Trace Recording

Feature trace recording is a semi-automated method for recording feature-to-code mappings during software development. It unlocks evolution as a new source of information for feature location.

Consider a developer Alice editing the pop method of a Stack class in Java as depicted in the image above. Feature-to-code mappings are indicated by corresponding colours. By labeling her edits with the feature she edits, we derive feature mappings for edited source code. We refer to such a label as feature context. It can be left empty when developers do not know the feature they edit. In our example, Alice does not know the feature of the moved line in her second edit and omits the feature context (i.e., sets it to null). From feature contexts we can compute feature mappings for the current code base but also for other variants. Assume there is a second developer, Bob, working on another variant (e.g., branch or fork) of the software. Bob’s variant might implement other features than Alice’s. Assume Bob’s variant implements the blue feature SafeStack but not the orange feature ImmutableStack. Although Alice made many edits to ImmutableStack, we can still derive feature mappings for Bob’s code. When Alice deletes code from ImmutableStack, we can infer that this code does not belong to ImmutableStack anymore. We thus introduce the new feature mapping ¬ImmutableStack for the deleted code that is still present in Bob’s variant (highlighted in purple in the image on the right).

Feature trace recording is the first step towards our vision for bridging the gap between clone-and-own and software product lines in our project VariantSync. You may read about it in our ICSE NIER paper or watch our talk on YouTube.