Simplifiez-vous les design patterns avec Symfony

Au cours de cette conférence, nous aborderons l'implémentation pratique des patrons Observateur et Service Locator au travers de deux libraries : le composant EventDispatcher du framework Symfony et Pimple, le conteneur d'injection de dépendance du framework Silex.

Transcript

1. http://brightsideof.com/wp-content/uploads/2012/11/m4-1024x679.jpg Simplifiez-vous les design patterns avec Symfony2
2. Patron de Conception « En génie logiciel, un patron de conception est une solution générique d'implémentation répondant à un problème spécifique. » http://fr.wikibooks.org/wiki/Patrons_de_conception
3. Disclaimer
4. Observateur Injection de Dépendance Service Locator
5. Observer
6. class Order { public function confirm() { $this->status = 'confirmed'; $this->save(); if ($this->logger) { $this->logger->log('New order...'); } $mail = new Email(); $mail->recipient = $this->customer->getEmail(); $mail->subject = 'Your order!'; $mail->message = 'Thanks for ordering...'; $this->mailer->send($mail); $mail = new Email(); $mail->recipient = 'sales@acme.com'; $mail->subject = 'New order to ship!'; $mail->message = '...'; $this->mailer->send($mail); } }
7. Trop de responsabilités! => SOLID Principle
8. Couplage fort!
9. Evolutivité limitée!
10. Maintenance peu aisée!
12. Un sujet, l’objet observable, émet un signal à des modules qui jouent le rôle d’observateurs.
14. interface ObserverInterface { function notify(ObservableInterface $subject); } interface ObservableInterface { function attach(ObserverInterface $observer); function notify(); }
15. Implémenter des Observateurs
16. class LoggerHandler implements ObserverInterface { public $logger; public function notify(ObservableInterface $subject) { $reference = $subject->getReference(); $this->logger->log('New order #'. $reference); } }
17. class CustomerNotifier implements ObserverInterface { public $mailer; public function notify(ObservableInterface $subject) { $mail = new Email(); $mail->recipient = $subject->customer->getEmail(); $mail->subject = 'Your order!'; $mail->message = 'Thanks for ordering...'; $this->mailer->send($mail); } }
18. class SalesNotifier implements ObserverInterface { public $mailer; public function notify(ObservableInterface $subject) { $mail = new Email(); $mail->recipient = 'sales@acme.com'; $mail->subject = 'New order to ship!'; $mail->message = '...'; $this->mailer->send($mail); } }
19. Notifier les Observateurs
20. class Order implements ObservableInterface { // ... private $observers; public function attach(ObserverInterface $observer) { $this->observers[] = $observer; } public function notifyObservers() { foreach ($this->observers as $observer) { $observer->notify($this); } } }
21. class Order implements ObservableInterface { public function confirm() { $this->status = 'confirmed'; $this->save(); $this->notifyObservers(); } }
22. class OrderController { public function finishOrderAction() { $order = new Order(); $order->attach(new LoggerNotifier($logger)); $order->attach(new CustomerNotifier($mailer)); $order->attach(new SalesNotifier($mailer)); $order->customer = $customer; $order->amount = 150; // Exécution des observateurs $order->confirm(); } }
23. SplObserver SplSubject
24. class SalesNotifier extends SplObserver { public $mailer; public function update(SplSubject $subject) { $mail = new Email(); $mail->recipient = 'sales@acme.com'; $mail->subject = 'New order to ship!'; $mail->message = '...'; $this->mailer->send($mail); } }
25. class Order extends SplSubject { // ... private $observers; public function attach(SplObserver $observer) { $this->observers[] = $observer; } public function notify() { foreach ($this->observers as $observer) { $observer->notify($this); } } }
26. Limitations?
27. EventDispatcher
28. Le Dispatcheur est un objet qui gère les connexions entre le sujet observé et ses observateurs (écouteurs).
29. "symfony/event-dispatcher": "2.1.*"
30. use Symfony\Component\EventDispatcher\Event; use Symfony\Component\EventDispatcher\EventDispatcher; use AFUP\ArticleListener; $dispatcher = new EventDispatcher(); // Déclaration des écouteurs $listener1 = array(new ArticleListener(), 'onDelete'); $listener2 = array(new ArticleListener(), 'onSave'); // Enregistrement des écouteurs $dispatcher->addListener('article.delete', $listener1); $dispatcher->addListener('article.pre_save', $listener2); // Notification des écouteurs $dispatcher->dispatch('article.pre_save', new Event());
31. Mise en Pratique
32. use AFUP\Model\Article; $article = new Article(); $article->setTitle('AFUP Design Patterns'); $article->setContent('Some **content**'); $article->save(); echo $article->getHtmlContent();
33. <p> Some <strong>content</strong> </p>
34. namespace AFUP\Model; use Propel\Runtime\Connection\ConnectionInterface; use dflydev\markdown\MarkdownParser; class Article extends \AFUP\Model\Base\Article { public function save(ConnectionInterface $con = null) { $parser = new MarkdownParser(); $html = $parser->transformMarkdown($this->getContent()); $this->setHtmlContent($html); $ret = parent::save($con); $this->updateLuceneIndex(); return $ret; } }
35. Le Sujet Observé
36. namespace AFUP\Model; use Symfony\Component\EventDispatcher\EventDispatcher; use AFUP\Model\Base\Article as BaseArticle; class Article extends BaseArticle { private $dispatcher; public function setDispatcher(EventDispatcher $dispatcher) { $this->dispatcher = $dispatcher; } }
37. namespace AFUP\Model; // ... use Propel\Runtime\Connection\ConnectionInterface; use AFUP\Event\ArticleEvent; class Article extends BaseArticle { // ... public function save(ConnectionInterface $con = null) { $event = new ArticleEvent($this); $this->dispatcher->dispatch('article.pre_save', $event); $ret = parent::save($con); $this->dispatcher->dispatch('article.post_save', $event); return $ret; } }
38. Propager un Evénement
39. namespace AFUP\Event; use Symfony\Component\EventDispatcher\Event; use AFUP\Model\Article; class ArticleEvent extends Event { private $article; public function __construct(Article $article) { $this->article = $article; } public function getArticle() { return $this->article; } }
40. Ajouter des écouteurs
41. namespace AFUP\Listener; use AFUP\Event\ArticleEvent; use dflydev\markdown\MarkdownParser; class ArticleListener { public function onPreSave(ArticleEvent $event) { $article = $event->getArticle(); $markdown = $article->getContent(); $parser = new MarkdownParser(); $html = $parser->transformMarkdown($markdown); $article->setHtmlContent($html); } }
42. namespace AFUP\Listener; use Zend\Search\Lucene\Document; use Zend\Search\Lucene\Document\Field; use AFUP\Event\ArticleEvent; use AFUP\Model\ArticlePeer; class LuceneListener { public function onPostSave(ArticleEvent $event) { $article = $event->getArticle(); // ... } }
43. namespace AFUP\Listener; // ... class LuceneListener { public function onPostSave(ArticleEvent $event) { $article = $event->getArticle(); $index = ArticlePeer::getLuceneIndex(); // remove existing entries foreach ($index->find('pk:'.$article->getId()) as $hit) { $index->delete($hit->id); } $doc = new Document(); $doc->addField(Field::Keyword('pk', $article->getId())); $doc->addField(Field::UnStored('title', $article->getTitle())); $doc->addField(Field::UnStored('content', $article->getContent())); $index->addDocument($doc); $index->commit(); } }
44. Enregistrer les écouteurs
45. use Symfony\Component\EventDispatcher\EventDispatcher; use AFUP\Listener\ArticleListener; use AFUP\Listener\LuceneListener; use AFUP\Model\Article; // Déclaration des écouteurs $listener1 = array(new ArticleListener(), 'onPreSave'); $listener2 = array(new LuceneListener(), 'onPostSave'); // Enregistrement des écouteurs $dispatcher = new EventDispatcher(); $dispatcher->addListener('article.pre_save', $listener1); $dispatcher->addListener('article.post_save', $listener2);
46. $article = new Article(); $article->setDispatcher($dispatcher); $article->setTitle('AFUP Design Patterns'); $article->setMarkdownContent( 'Some **markdown** content' ); $article->save();
47. Injection de dépendance
48. Single Responsability Open / Close principle Liskov substitution Interface segregation Dependency Injection
49. « Dependency Injection is where components are given their dependencies through their constructors, methods, or directly into fields. » http://picocontainer.codehaus.org/injection.html
50. Mauvaise Conception Initiale
51. class Mailer { public function send(Message $message) { try { $transport = new SMTPTransport( 'smtp.foo.com', 1234, 'mailer', 'p$wD^' ); return $transport->send($message); } catch (TransportException $e) { $logger = Logger::getInstance(); $logger->log('Unable to send message to...'); $logger->logException($e); throw $e; } } }
52. $message = new Message(); $message->setFrom('me@example.com'); $message->setTo('you@example.com'); $message->setSubject('Bonjour ...'); $message->setBody('Hello ...'); $mailer = new Mailer(); $mailer->send($message);
53. ça fonctionne !
54. Oui mais ?!!!
55. $transport = new SMTPTransport( 'smtp.foo.com', 1234, 'mailer', 'p$wD^' );
56. Je veux utiliser un transport différent…
57. Je veux configurer le SMTP en dev et en prod…
58. $logger = Logger::getInstance(); $logger->log('Unable to...'); $logger->logException($e);
59. Si le logger n’existe pas ?
60. Si je veux changer la configuration du logger?
61. Je veux tester mon code et je n’y arrive pas…
62. La Solution?
63. Injecter ses dépendances au Mailer
64. What ???
65. Injection par les propriétés
66. class Mailer { public $transport; public function send(Message $message) { try { $this->transport->send($message); } catch (TransportException $e) { // ... } } }
67. $message = Message(); $message->setFrom('me@example.com'); $message->setTo('you@example.com'); $message->setSubject('Bonjour ...'); $message->setBody('Hello ...'); $transport = new SMTPTransport('...'); $mailer = new Mailer(); $mailer->transport = $transport; $mailer->send($message);
68. Injection par constructeur
69. class Mailer { private $transport; function __construct(Transport $t) { $this->transport = $t; } }
70. $message = Message(); $message->setFrom('me@example.com'); // ... $transport = new SMTPTransport('...'); $mailer = new Mailer($transport); $mailer->send($message);
71. Injection par un mutateur
72. class Mailer { private $logger; function setLogger(Logger $logger) { $this->logger = $logger; } }
73. class Mailer { // ... public function send(Message $message) { try { $this->transport->send($message); } catch (TransportException $e) { if (null !== $this->logger) { $this->logger->log('...'); $this->logger->logException($e); throw $e; } } } }
74. $message = Message(); // ... $logger = new FileLogger('/to/dev.log'); $transport = new SMTPTransport('...'); $mailer = new Mailer($transport); $mailer->setLogger($logger); $mailer->send($message);
75. Découplage avec les interfaces
76. class Mailer { function __construct(TransportInterface $t) { $this->transport = $t; } function setLogger(LoggerInterface $logger) { $this->logger = $logger; } }
77. class SMTPTransport implements TransportInterface { } class MailTransport implements TransportInterface { } class NullTransport implements TransportInterface { }
78. Bénéfices vs Pertes ?!
79. Configurabilité Modularité Testabilité
80. Construction un peu plus Complexe
81. Service Locator
82. « Le patron service locator permet d’encapsuler les mécanismes d’obtention d’un service. »
83. # composer.json { "require": { "pimple/pimple": "1.0.*" } }
84. Global Configuration + Lazy Services = Container
85. Paramètres Globaux de Configuration
86. $pimple = new Pimple(); $pimple['logger.file'] = '/path/to/dev.log'; $pimple['logger.severity'] = 200; $pimple['transport.smtp.host'] = 'smtp.foo.com'; $pimple['transport.smtp.port'] = 1234; $pimple['transport.smtp.user'] = 'mailer'; $pimple['transport.smtp.passwd'] = '^p4$$W0rD*';
87. Enregistrer des services
88. $pimple['logger'] = $pimple->share(function ($c) { if (!is_writable($c['logger.file'])) { throw new Exception('...'); } $logger = new Logger($c['logger.file']); if (isset($c['logger.severity'])) { $logger->setSeverity($c['logger.severity']); } return $logger; });
89. $pimple['mailer.transport'] = $pimple ->share(function ($c) { return new SMTPTransport( $c['transport.smtp.host'], $c['transport.smtp.port'], $c['transport.smtp.user'], $c['transport.smtp.passwd'] ); });
90. $pimple['mailer'] = $pimple->share(function ($c) { $mailer = new Mailer($c['mailer.transport']); if (isset($c['logger'])) { $mailer->setLogger($c['logger']); } return $mailer; });
91. Initialisation des services à la demande
92. $pimple = new Pimple(); $pimple['logger.file'] = '/path/to/dev.log'; $pimple['logger.severity'] = 200; // ... $message = Message(); $message->setFrom('me@example.com'); // ... // Création à la demande du mailer $pimple['mailer']->send($message);
93. Pour aller plus loin!
94. DependencyInjection