Explicit Tool Support for Implicit Layer Activation

Abstract

Implicit Layer Activation (ILA) is a declarative mechanism to scope behavior adaptations in Context-oriented Programming (COP). ILA binds the activation status of a layer to a Boolean condition. The layer is active as long as the given condition evaluates to true. This mechanism to scope layer activations is very powerful, but without dedicated tool support, it may be hard to debug due to its implicitness. A solution that can mitigate this is proper tool support, which is expensive to build and can be highly domain-specific. We have previously shown that by building the language extension not from scratch but by relying on a common more powerful shared concept, Active Expressions, the implementation becomes simpler and more elegant since it does not require deep integration into the ContextJS implementation. In this paper we show how providing tool support for ILA makes implicit dependencies to state changes more explicit. We show how such tool support can be implemented by leveraging the existing Active Expression tool suite. We illustrate the usage based on a catalog of COP questions from literature.