Functional Python Programming

Cross-cutting concerns

One general principle behind decorators is to allow us to build a composite function from the decorator and the original function to which the decorator is applied. The idea is to have a library of common decorators that can provide implementations for common concerns.

We often call these cross-cutting concerns because they apply across several functions. These are the sorts of things that we would like to design once via a decorator and have them applied in relevant classes throughout an application or a framework.

Concerns that are often centralized as described previously include the following:

• Logging
• Auditing
• Security
• Handling incomplete data

A logging decorator, for example, might write standardized messages to the application's ...