The feature signatures of evolving programs

As programs evolve, their code increasingly becomes tangled by programmers and requirements. This mosaic quality complicated program comprehension and maintenance. Many of these activities can benefit from viewing the program as a collection of features. We introduce an inexpensive and easily comprehensible summary of program changes called the feature signature and investigate its properties. We find a remarkable similarity in the nature of feature signatures across multiple nontrivial programs, developers and magnitude changes. This indicates that feature signatures are a meaningful notion worth studying. We then show numerous applications of feature signatures to software evolution, establishing their utility.