Feature and Class Models in Clafer: Mixed, Specialized, and Coupled

We present Clafer, a class modeling language with first-class support for feature modeling.We designed Clafer as a concise notation for class models, feature models, mixtures of class and feature models (such as components with options), and models that couple feature models and class models via constraints (such as mapping feature configurations to component configurations). Clafer also allows arranging models into multiple specialization and extension layers via constraints and inheritance. We identified four key mechanisms allowing a class modeling language to express feature models concisely and show that Clafer meets its design objectives using a sample product line.