A core calculus for dynamic delta-oriented programming

Delta-oriented programming (DOP) is a flexible approach to the implementation of software product lines (SPLs). Delta-oriented SPLs consist of a code base (a set of delta modules encapsulating changes to object-oriented programs) and a product line declaration (providing the connection of the delta modules with the product features). In this paper, we present a core calculus that extends DOP with the capability to switch the implemented product configuration at runtime. A dynamic delta-oriented SPL is a delta-oriented SPL with a dynamic reconfiguration graph that specifies how to switch between different feature configurations. Dynamic DOP supports also (unanticipated) software evolution such that at runtime, the product line declaration, the code base and the dynamic reconfiguration graph can be changed in any (unanticipated) way that preserves the currently running product, which is essential when evolution affects existing features. The type system of our dynamic DOP core calculus ensures that the dynamic reconfigurations lead to type safe products and do not cause runtime type errors.