When Easy Is Hard - Speaker Deck

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WHEN EASY IS HARD 12 Mar 2015

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Marek Matulka Software Engineer at SensioLabsUK @super_marek

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#Symfony_Live @SensioLabsUK

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Take it easy!

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Framework

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Convenience

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User::findOrFail($id)]); } }

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getDoctrine() ->getRepository('AcmeConferenceBundle:Conference') ->find($id); $this->get('acme_conference.enrolment.service') ->enrol($conference, $this->getUser())) { return new Response('Success!'); } }

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Cost

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price speed quality

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Let’s grow!

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New features

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getDoctrine() ->getRepository('AcmeConferenceBundle:Conference')->find($id); if ( $enrolment = $this->get('acme_conference.enrolment.service') ->enrol($conference, $this->getUser()) ) { $em = $this->getDoctrine()->getEntityManager(); $em->persist($enrolment); $em->flush(); $this->get('acme_conference.notification.service') ->notify($this->getUser(), 'success'); return $this->redirect('registration_successful') } return $this->redirect('registration_failed'); } } © http://warrenmars.com/

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Difficult to maintain

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It takes longer to add new features

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Yummy spaghetti code! © http://momeefriendsli.com/2013/04/16/dinner-and-a-book/

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…and there are no tests!

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No one wants to touch it

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Let’s rewrite it!

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not so happy customer © https://channelinstincts.files.wordpress.com/2014/01/unhappy-customer.jpg

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price speed quality

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price speed sustainability

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Do you expect the plumber to “apply the workaround” to your leaking pipe? © http://www.asbestosjustice.co.uk/wp-content/uploads/2014/11/jobs-to-consider-7-plumber-1093362-TwoByOne.jpg

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What has happened?

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What has happened? - too close to the framework - no separation of concerns - mixed layers - no tests!

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delivered features time Features delivered over time

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How to avoid?

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Forget the framework!

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Decouple your code

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Decoupled code - improves readability - can be reused - easy to maintain - easy to change

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Let’s do it!

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Global scope is a smell! Avoid hidden dependencies

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class RegistrationController { public function registerAction($id) { $learner = Session::getUser(); $conference = Conference::findOrFail($id); Enrolment::enrolLearnerInConference($learner, $conference); Mail::send('emails.welcome', array('key' => 'value'), function($message) use ($learner, $conference) { $message->to($learner->email(), $learner->name()) ->subject('Thanks for registering for '.$conference->name().'!'); } ); } }

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Inject only what you need

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class RegistrationController { public function __construct( Enrolment $enrolment, Learner $learner, Notifier $notifier ) { $this->enrolment = $enrolment; $this->learner = $learner; $this->notifier = $notifier; } public function registerAction(Conference $conference) { $enrolment = $this->enrolment->enrolLearnerInConference($this->learner, $conference); $this->notifier->successfulEnrolment($enrolment); } }

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Don’t mix layers

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class RegistrationController { public function __construct( EnrolmentHandler $enrolmentHandler, Learner $learner ) { $this->enrolmentHandler = $enrolmentHandler; $this->learner = $learner; } public function registerAction(Conference $conference) { $this->enrolmentHandler->handle( new EnrolLearnerInConference($this->learner, $conference); ); } }

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class EnrolmentHandler { public function __construct(EnrolmentRepository $enrolmentRepository, Mailer $mailer) { $this->repository = $enrolmentRepository; $this->mailer = $mailer; } public function handle(EnrolLearnerInConference $enrolmentCommand) { $enrolment = $enrolmentCommand->execute(); $this->repository>save($enrolment); $this->mailer->send('emails.welcome', array('key' => 'value'), function($message) use ($enrolment) { $message->to($enrolment->learner()->email(), $enrolment->learner()->name()) ->subject('Thanks for registering for '.$enrolment->conference->name().'!'); }); }

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Invert dependencies

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class EnrolmentHandler { public function __construct( EnrolmentRepository $enrolmentRepository, EnrolmentNotifier $notifier ) { $this->repository = $enrolmentRepository; $this->notifier = $notifier; } public function handle(EnrolLearnerInConference $enrolmentCommand) { if ($enrolment = $enrolmentCommand->execute()) { $this->repository->save($enrolment); $this->notifier->successfulEnrolment($enrolment); } } }

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interface EnrolmentNotifier { /** * @param Enrolment $enrolment * * @throws FaildToNotify */ public function successfulEnrolment(Enrolment $enrolment); }

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interface EnrolmentRepository { /** * @param integer $id * @return Enrolment */ public function findOneById($id); /** * @param Enrolment $enrolment */ public function save(Enrolment $enrolment); }

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EnrolmentRepository DoctrineEnrolmentRepository InMemoryEnrolmentRepositor y EntityManager Dependency Inversion InMemoryRepository

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Clean Code

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Layered Architecture

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User Interface Application Domain Infrastructure

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Clean Architecture by Robert C. Martin

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Entities Use Cases Controllers Web

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Entities Use Cases Controllers Web Framework Drivers Interface Adapters Application Business Rules Enterprise Business Rules

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aka Ports & Adapters Hexagonal Architecture

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UI Adapter Log Adapter Data Storage Adapter Domain External Data Adapter

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UI Adapter Log Adapter Data Storage Adapter Domain External Data Adapter UI client port log adapter port persistence layer port data provider port

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UI Adapter Monolog Test Adapter NullLogger Doctrine InMemory Domain Facebook API Mock API

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Why bother?

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Why bother writing clean code? - decoupled - reusable - testable - maintainable - changeable

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Sustainable!

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class DoctrineEnrolmentRepository implements EnrolmentRepository { public function __construct(EntityManager $entityManager) { $this->em = $entityManager; } public function findOneById($id) { return $this->em->find(Enrolment::class, $id); } public function save(Enrolment $enrolment) { $this->em->persist($enrolment); $this->em->flush($enrolment); } }

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class InMemoryEnrolmentRepository implements EnrolmentRepository { public function __construct() { $this->repository = new InMemoryRepository(); } public function findOneById($id) { return $this->repository->findById($id); } public function save(Enrolment $enrolment) { $this->repository->save($enrolment); } }