The Keyword Revolution: promoting language constructs for data access to first class citizens

An ongoing trend is to develop new mechanisms for composing software modules that resemble the relations between corresponding problem-domain entities and thus enable a natural decomposition of software for an increasing number of problem domains. However, we have observed that today's programming languages hard-wire a fixed set of composition mechanisms, usually in terms of keywords. To overcome this limitation, we have proposed the Co-op approach enabling developers to implement an open-ended number of composition mechanisms as first-class citizens. Extending our previous prototype which focused on the composition of behavior, this paper reports on our prototype Co-op/II which facilitates implementing composition mechanisms for data access. We show that our approach is sufficient to realize several styles, e.g., of sharing data between sub classes, of controlling visibility, and of behavioral modifiers like synchronization of data access, converting or persisting data