Join Point Models
The advice-related component of an aspect-oriented language defines a join point model (JPM). A JPM defines three things:
- When the advice can run. These are called join points because they are points in a running program where additional behavior can be usefully joined. A join point needs to be addressable and understandable by an ordinary programmer to be useful. It should also be stable across inconsequential program changes in order for an aspect to be stable across such changes. Many AOP implementations support method executions and field references as join points.
- A way to specify (or quantify) join points, called pointcuts. Pointcuts determine whether a given join point matches. Most useful pointcut languages use a syntax like the base language (for example, AspectJ uses Java signatures) and allow reuse through naming and combination.
- A means of specifying code to run at a join point. AspectJ calls this advice, and can run it before, after, and around join points. Some implementations also support things like defining a method in an aspect on another class.
Join-point models can be compared based on the join points exposed, how join points are specified, the operations permitted at the join points, and the structural enhancements that can be expressed.
Read more about this topic: Aspect-oriented Programming
Famous quotes containing the words join, point and/or models:
“I ask you to join in a re-United States. We need to empower our people so they can take more responsibility for their own lives in a world that is ever smaller, where everyone counts.... We need a new spirit of community, a sense that we are all in this together, or the American Dream will continue to wither. Our destiny is bound up with the destiny of every other American.”
—Bill Clinton (b. 1946)
“I would rather produce my passions than brood over them at my expense; they grow languid when they have vent and expression. It is better that their point should operate outwardly than be turned against us.”
—Michel de Montaigne (1533–1592)
“Friends broaden our horizons. They serve as new models with whom we can identify. They allow us to be ourselves—and accept us that way. They enhance our self-esteem because they think we’re okay, because we matter to them. And because they matter to us—for various reasons, at various levels of intensity—they enrich the quality of our emotional life.”
—Judith Viorst (20th century)