Expanding Event Systems to Support Signals by Enabling the Automation of Handler Bindings

In event-driven programming we can react to an event by binding methods to it as handlers, but such a handler binding in current event systems is explicit and requires explicit reason about the graph of event propagation even for straightforward cases. On the other hand, the handler binding in reactive programming is implicit and constructed through signals. Recent approaches to support either event-driven programming or reactive programming show the need of using both the two styles in a program. We propose an extension to expand event systems to support reactive programming by enabling the automation of handler bindings. With such an extension programmers can use events to cover both the implicit style in reactive programming and the explicit style in event-driven programming. We first describe the essentials of reactive programming, signals and signal assignments, in terms of events, handlers, and bindings, then point out the lack of automation in existing event systems. Unlike most research activities we expand event systems to support signals rather than port signals to event systems. In this paper we also show a prototype implementation and translation examples to evaluate the concept of automation. Furthermore, the comparison with the predicate pointcuts in aspect-oriented programming and the details of the experimental compiler are discussed.