Robert Lemke gave a presentation titled "Create Clean Code with Aspect-Oriented Programming" at the WebExpo 2010 conference in Prague. The presentation introduced aspect-oriented programming (AOP) and how it can be used to separate cross-cutting concerns in code to improve modularity. It provided an overview of AOP concepts like aspects, join points, pointcuts, and advices. Lemke also demonstrated AOP using the FLOW3 framework, explaining its implementation and features like advice types and pointcut designators. He argued that AOP allows infrastructure code to be removed from models and cross-cutting concerns to be centralized and unit tested.

1. Robert Lemke
Create Clean Code with Aspect-Oriented Programming
WebExpo 2010, Prague
Photo: Robert Szlivka

2. Robert Lemke
chief architect of TYPO3 Phoenix and FLOW3
co-founder of the TYPO3 Association
34 years old
lives in Lübeck, Germany
1 wife, 1 daughter, 1 espresso machine
likes drumming

3. www.typo3.org

4. www.typo3.org

5. www.typo3.org
Create Clean Code with AOP WebExpo 2010, Prague

9. = PHP 5.3 Full Stack Application Framework

10. DI Dependency Injection DRY
YAA
OOP Object-Oriented Programming
YAGNI
AOP Aspect-Oriented Programming
CoC
MVC Model View Controller
POPO Plain Old PHP Object TDD

11. /**
* Creates a new post
*
* @param F3BlogDomainModelPost $newPost A fresh Post object which has not yet been
* added to the repository
* @return void
*/
public function createAction(F3BlogDomainModelPost $newPost) {
if ($this->policyService->isGranted($this->currentUser, __CLASS__, __METHOD__) {
$this->blog->addPost($newPost);
$this->flashMessageContainer->add('Your new post was created.');
$this->systemLogger->log('A new post was created.', LOG_INFO);
$this->notificationService->notify('A new post was created.', 'robert@typo3.org');
} else {
$this->systemLogger->log('Someone tried to create a post.', LOG_WARNING);
throw new F3FLOW3SecurityExceptionAccessDeniedException('Tried to create.');
}
$this->redirect('index');
}
Create Clean Code with AOP WebExpo 2010, Prague

12. /**
* Creates a new post
*
* @param F3BlogDomainModelPost $newPost A fresh Post object which has not yet been
* added to the repository
* @return void
*/
public function createAction(F3BlogDomainModelPost $newPost) {
if ($this->policyService->isGranted($this->currentUser, __CLASS__, __METHOD__) {
$this->blog->addPost($newPost);
$this->flashMessageContainer->add('Your new post was created.');
$this->systemLogger->log('A new post was created.', LOG_INFO);
$this->notificationService->notify('A new post was created.', 'robert@typo3.org');
} else {
$this->systemLogger->log('Someone tried to create a post.', LOG_WARNING);
throw new F3FLOW3SecurityExceptionAccessDeniedException('Tried to create.');
}
$this->redirect('index');
}
Create Clean Code with AOP WebExpo 2010, Prague

13. Create Clean Code with AOP WebExpo 2010, Prague

14. AOP
Create Clean Code with AOP WebExpo 2010, Prague

15. Aspect-Oriented Programming
programming paradigm
separates concerns to improve modularization
OOP modularizes concerns into objects
AOP modularizes cross-cutting concerns into aspects
Create Clean Code with AOP WebExpo 2010, Prague

16. /**
* Creates a new post
*
* @param F3BlogDomainModelPost $newPost A fresh Post object which has not yet been
* added to the repository
* @return void
*/
public function createAction(F3BlogDomainModelPost $newPost) {
$this->blog->addPost($newPost);
$this->flashMessageContainer->add('Your new post was created.');
$this->redirect('index');
}
Create Clean Code with AOP WebExpo 2010, Prague

17. Concerns?
Create Clean Code with AOP WebExpo 2010, Prague

18. Concerns
Separation of Concerns
group features and behavior into manageable parts
have a specific purpose and business to take care of
Cross-Cutting Concerns
are the party poopers who want to have a say in everything
Create Clean Code with AOP WebExpo 2010, Prague

19. Cross-Cutting Concerns
Logging
Security
Persistence
Global Business Logic
Dirty Hacks
Create Clean Code with AOP WebExpo 2010, Prague

20. We don't want infrastructure code
in our models.
Create Clean Code with AOP WebExpo 2010, Prague

21. We want to unit-test even
cross-cutting concerns
Create Clean Code with AOP WebExpo 2010, Prague

22. We want to centralize
security-related code
Create Clean Code with AOP WebExpo 2010, Prague

23. AOP Lingo
Create Clean Code with AOP WebExpo 2010, Prague

24. Aspect
Part of the application where cross-cutting concerns are implemented
In FLOW3 aspects are classes annotated with @aspect
Create Clean Code with AOP WebExpo 2010, Prague

25. Join Point
Is a single point in the call graph
Method Execution
Exception
Represents an event, not a location
Create Clean Code with AOP WebExpo 2010, Prague

26. Pointcut
A set of join points where advices could be executed
can be composed
can be named
Create Clean Code with AOP WebExpo 2010, Prague

27. Advice
Action to take at a join points defined by the point cut
Create Clean Code with AOP WebExpo 2010, Prague

28. DEMO
Inspiring people to
Hitchhiker's Guide to FLOW3 share

29. Kinds of Advice
Advice types supported by FLOW3:
@before
@afterreturning
@afterthrowing
@after
@around
Inspiring people to
Hitchhiker's Guide to FLOW3 share

30. Pointcut Designators
method(F3MyPackageMyClass->myMethod())
class(F3MyPackageMyClass)
within(F3MyPackageMyInterface)
classTaggedWith(someTag)
methodTaggedWith(anotherTag)
setting(Demo.Stuff.SomeSetting = "yeah, do it")
filter(F3MyPackageMyCustomFilterImplementation)
fi
Inspiring people to
Hitchhiker's Guide to FLOW3 share

31. Runtime Evaluations
evaluate(coffee.kind == "Arabica")
Inspiring people to
Hitchhiker's Guide to FLOW3 share

32. Compound Pointcuts
! /**
! * @around method(.*Controller->(new|create|edit|update|delete)Action()) &&
!methodTaggedWith(anybodyMayAccessThis)
! */
! public function interceptMethodCalls($joinPoint) {
...
}
Inspiring people to
Hitchhiker's Guide to FLOW3 share

33. DEMO
Inspiring people to
Hitchhiker's Guide to FLOW3 share

34. FLOW3's AOP implementation
based on proxy classes
unlike with most pre-processors line numbers stay the same
no scaffolding
0 Lines of generated code which need to be maintained by you
fast (on the second hit)
Inspiring people to
Hitchhiker's Guide to FLOW3 share

35. Inspiring people to
Hitchhiker's Guide to FLOW3 share

36. Inspiring people to
Hitchhiker's Guide to FLOW3 share

37. Progress
FLOW3 1.0.0
Create Clean Code with AOP WebExpo 2010, Prague

38. Further Reading
FLOW3 Website
http://flow3.typo3.org
FLOW3 Download
http://flow3.typo3.org/download
git://git.typo3.org/FLOW3/Distributions/Base.git
TYPO3 Forge
http://forge.typo3.org
Further Reading
http://flow3.typo3.org/about/principles/further-reading
Create Clean Code with AOP WebExpo 2010, Prague

39. Questions
Email: robert@typo3.org
Blog: http://robertlemke.de/blog
Twitter: @t3rob
Slides: http://slideshare.net/rlmp
Create Clean Code with AOP WebExpo 2010, Prague