Expressing layer dependencies in Context-oriented Programming is cumbersome because until now no facility has been introduced to control the activation and deactivation of layers. This paper presents a novel reflective interface that provides such control without compromising efficiency. This allows expressing complex application-defined dependencies between layers where the activation or deactivation of a layer requires the activation or deactivation of another one. The activation or

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... on of specific layers can also be prohibited based on application-defined conditions.