This document discusses aspect-oriented programming and how aspects can be used to clean up code by encapsulating cross-cutting concerns. It provides examples of common cross-cutting concerns like logging, validation, and transactions. The presenter explains what aspects are and how they work, including different types of advices. Demonstrations are provided to show refactoring code to use aspects and testing aspects. The overall message is that aspects promote cleaner, more reusable code by separating cross-cutting concerns from the main code logic.

1. Aspect-Oriented
Programming
How can aspects clean your code?
@BasiaFusinska

2. Aspect-Oriented Programming How can aspects clean your code? 2
About me
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@basiafusinska
Architect
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3. Aspect-Oriented Programming How can aspects clean your code?
Agenda
3
❖ What the hell...are aspects?
❖ Some examples of AOP
❖ Demo 1: refactor your way to aspects
❖ Every-day aspects
❖ Demo 2: some not-so-obvious aspects
❖ How to test aspects
❖ Demo 3: testing in practice
❖ Q & A

4. Aspect-Oriented Programming How can aspects clean your code?
Some history
4
❖ Gregor Kiczales (1997), Xerox PARC
❖ OOP is unable to solve some common problems
❖ Aspects encapsulate cross-cutting concerns and make them easier to
reuse

5. Aspect-Oriented Programming How can aspects clean your code?
Cross cutting concerns
5
❖ Cross-cutting concerns are scattered throughout the code
❖ Code becomes difficult to develop and modify
❖ Code breaks the Single Responsibility Principle

6. Aspect-Oriented Programming How can aspects clean your code?
Cross-cutting concerns are everywhere!
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❖ Logging
❖ Validation
❖ Persistence
❖ Caching
❖ Synchronization
❖ Transactions
❖ Exception handling
❖ Authentication
❖ Authorization
❖ ...

7. Aspect-Oriented Programming How can aspects clean your code?
What the heck are aspects?
6
❖ Purpose: cross-cutting concerns – pieces of functionality used across
multiple parts of a system
❖ Job: the advice – code that performs cross-cutting concern
❖ Map: pointcut – set of joinpoints
❖ How: weaving

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How it works?

9. Aspect-Oriented Programming How can aspects clean your code?
Types of advices?
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❖ Entry
❖ Exit
❖ Exception
❖ Success
❖ Around
❖ Method boundaries vs method interceptions

10. Aspect-Oriented Programming How can aspects clean your code?
Some benefits of AOP
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❖ Code is cleaner
❖ DRY (Don’t Repeat Yourself): promotes code reuse
❖ Better encapsulation

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Aspect-Oriented Programming How can aspects clean your code?
Demonstration #1
Refactor your way to aspects

12. Aspect-Oriented Programming How can aspects clean your code?
You’ve been using AOP without knowing it
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❖ IHttpModule - requests boundary aspects
❖ IActionFilter - code run before and after the action execution
❖ ASP.Net MVC Authentication - AuthorizeAttribute
❖ Actions per request (Session Open/Close, ORM changes saving)

13. 11
Aspect-Oriented Programming How can aspects clean your code?
Demonstration #2
Some not-so-obvious aspects

14. Aspect-Oriented Programming How can aspects clean your code?
Testing aspects
12
❖ Testing the pointcut – testing if aspects were used in correct places
❖ Testing the advice – testing if the aspects are doing what they are
supposed to do

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Aspect-Oriented Programming How can aspects clean your code?
Demonstration #3
Testing aspects

16. Thank you :)
Any questions?
@basiafusinska
barbarafusinska.co
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