Instance pointcuts: selecting object sets based on their usage history

At runtime, how objects have to be handled frequently depends on how they were used before. But with current programming-language support, selecting objects according to their previous usage patterns often results in scattered and tangled code. In this study, we propose a new kind of pointcut, called Instance Pointcuts, for maintaining sets that contain objects with a specified usage history. Instance pointcut specifications can be reused, by refining their selection criteria, e.g., by restricting the scope of an existing instance pointcut; and they can be composed, e.g., by set operations. These features make instance pointcuts easy to evolve according to new requirements. Our approach improves modularity by providing a fine-grained mechanism and a declarative syntax to create and maintain usage-specific object sets.