On Type Checking Delta-Oriented Product Lines

A Software Product Line (SPL) is a set of similar programs generated from a common code base. Delta Oriented Programming (DOP) is a flexible approach to implement SPLs. Efficiently type checking an SPL (i.e., checking that all its programs are well-typed) is challenging. This paper proposes a novel type checking approach for DOP. Intrinsic complexity of SPL type checking is addressed by providing early detection of type errors and by reducing type checking to satisfiability of a propositional formula. The approach is tunable to exploit automatically checkable DOP guidelines for making an SPL more comprehensible and type checking more efficient. The approach and guidelines are formalized by means of a core calculus for DOP of product lines of Java programs.