Pointcut

In aspect-oriented programming, a pointcut is a set of join points. Pointcut specifies where exactly to apply advice, which allows separation of concerns and helps in modularizing business logic. Pointcuts are often specified using class names or method names, in some cases using regular expressions that match class or method name. Different frameworks support different Pointcut expressions; AspectJ syntax is considered as de facto standard. Frameworks are available for various programming languages like Java, Perl, Ruby, and many more which support pointcut. Due to limitations in various programming languages, cross-cutting concern has not modularized. Cross-cutting concern refers to parts of software that logically belong to one module and affect the whole system: this could be security or logging, for example. Aspect-oriented programming tries to solve these cross cutting concerns by allowing programmers to write modules called aspects, which contain pieces of code executed at particular point. The expressions required to select a particular point led to creation of Pointcut Expressions. Whenever the program execution reaches one of the join points described in the pointcut, a piece of code associated with the pointcut (called advice) is executed. This allows a programmer to describe where and when additional code should be executed in addition to already-defined behavior. Pointcut permits the addition of aspects to existing software, as well as the design of software with a clear separation of concerns, wherein the programmer weaves (merges) different aspects into a complete application. Suppose there is an application where we can modify records in a database. Whenever users modify the database, we want to have a log of information regarding who is modifying the records. The traditional way to log is to call a log method just before modifying the database. With aspect-oriented programming, we can apply pointcut to the Modify Database method and have an advice that is called to log the required information.