AspectJ Cookbook

Chapter 15. Defining Aspect Relationships

Introduction

Aspects in AspectJ are objects in their own right and they benefit from the traditional object-oriented (OO) mechanisms that make object orientation such a great approach for software development.

When using the OO concepts of association and composition, then the rules for aspects are fairly simple: an aspect can contain or use other classes without using any unique syntax. If you ignore some irregular method signatures, a class can use an aspect as if it were just another class.

This chapter deals with the details of inheritance between aspects and classes and some of the special things to consider when defining these relationships.

15.1. Inheriting Pointcut Definitions

Problem

You want to create pointcut declarations in an aspect that can then be reused using inheritance.

Solution

Create an abstract aspect. Define within the abstract aspect the reusable pointcut logic using the appropriate public, protected, or default access modifiers. Finally, inherit that abstract aspect into your subaspects to reuse the declared pointcuts.

Discussion

Pointcuts are subject to a similar set of rules as normal methods when using inheritance. If a pointcut is declared public, protected, or default, then its logic can be inherited and reused within other aspects.

Example 15-1 shows an abstract aspect that provides a base for inheriting its defined pointcuts.

Example 15-1. Using an abstract aspect to define reusable pointcut logic

public abstract aspect ...