Aspect-oriented programming

In computing, aspect-oriented programming (AOP) is a programming paradigm that aims to increase modularity by allowing the separation of cross-cutting concerns. It does so by adding behavior to existing code (an advice) without modifying the code, instead separately specifying which code is modified via a "pointcut" specification, such as "log all function calls when the function's name begins with 'set'". This allows behaviors that are not central to the business logic (such as logging) to be added to a program without cluttering the code of core functions.

AOP includes programming methods and tools that support the modularization of concerns at the level of the source code, while aspect-oriented software development refers to a whole engineering discipline.

Aspect-oriented programming entails breaking down program logic into cohesive areas of functionality (so-called concerns). Nearly all programming paradigms support some level of grouping and encapsulation of concerns into separate, independent entities by providing abstractions (e.g., functions, procedures, modules, classes, methods) that can be used for implementing, abstracting, and composing these concerns. Some concerns "cut across" multiple abstractions in a program, and defy these forms of implementation. These concerns are called cross-cutting concerns or horizontal concerns.

Logging exemplifies a cross-cutting concern because a logging strategy must affect every logged part of the system. Logging thereby crosscuts all logged classes and methods.