op

OP, O.P., Op, or Op. may refer to:

• Opus number, used to denote one work of musical composition from many
• Out of print, a status of a book title at a publishing house
• Opposite prompt, a stage right prompt corner on a theatre stage

Attribute-oriented programming (AOP) is a program-level marking technique. Programmers can mark program elements (e.g. classes and methods) to indicate that they maintain application-specific or domain-specific semantics. For example, some programmers may define a "logging" attribute and associate it with a method to indicate the method should implement a logging function, while other programmers may define a "web service" attribute and associate it with a class to indicate the class should be implemented as a web service. Attributes separate application's core logic (or business logic) from application-specific or domain-specific semantics (e.g. logging and web service functions). By hiding the implementation details of those semantics from program code, attributes increase the level of programming abstraction and reduce programming complexity, resulting in simpler and more readable programs. The program elements associated with attributes are transformed to more detailed programs by a supporting tool (e.g. preprocessor). For example, a preprocessor may insert a logging program into the methods associated with a "logging" attribute.