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
   

   View Slide

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
   

   View Slide

3. Disclaimer
   

   View Slide

4. Observateur
   Injection de Dépendance
   Service Locator
   

   View Slide

5. Observer
   

   View Slide

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);
   }
   }
   

   View Slide

7. Trop de
   responsabilités!
   => SOLID Principle
   

   View Slide

8. Couplage
   fort!
   

   View Slide

9. Evolutivité
   limitée!
   

   View Slide

10. Maintenance
    peu aisée!
    

    View Slide

11. View Slide

12. Un sujet, l’objet
    observable, émet un
    signal à des modules
    qui jouent le rôle
    d’observateurs.
    

    View Slide

13. View Slide

14. interface ObserverInterface
    {
    function notify(ObservableInterface $subject);
    }
    interface ObservableInterface
    {
    function attach(ObserverInterface $observer);
    function notify();
    }
    

    View Slide

15. Implémenter des
    Observateurs
    

    View Slide

16. class LoggerHandler implements ObserverInterface
    {
    public $logger;
    public function notify(ObservableInterface $subject)
    {
    $reference = $subject->getReference();
    $this->logger->log('New order #'. $reference);
    }
    }
    

    View Slide

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);
    }
    }
    

    View Slide

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);
    }
    }
    

    View Slide

19. Notifier les
    Observateurs
    

    View Slide

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);
    }
    }
    }
    

    View Slide

21. class Order implements ObservableInterface
    {
    public function confirm()
    {
    $this->status = 'confirmed';
    $this->save();
    $this->notifyObservers();
    }
    }
    

    View Slide

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();
    }
    }
    

    View Slide

23. SplObserver
    SplSubject
    

    View Slide

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);
    }
    }
    

    View Slide

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);
    }
    }
    }
    

    View Slide

26. Limitations?
    

    View Slide

27. EventDispatcher
    

    View Slide

28. Le Dispatcheur est un
    objet qui gère les
    connexions entre le
    sujet observé et ses
    observateurs
    (écouteurs).
    

    View Slide

29. "symfony/event-dispatcher": "2.1.*"
    

    View Slide

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());
    

    View Slide

31. Mise en Pratique
    

    View Slide

32. use AFUP\Model\Article;
    $article = new Article();
    $article->setTitle('AFUP Design Patterns');
    $article->setContent('Some **content**');
    $article->save();
    echo $article->getHtmlContent();
    

    View Slide

33. 
    Some content
    
    

    View Slide

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;
    }
    }
    

    View Slide

35. Le Sujet
    Observé
    

    View Slide

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;
    }
    }
    

    View Slide

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;
    }
    }
    

    View Slide

38. Propager un
    Evénement
    

    View Slide

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;
    }
    }
    

    View Slide

40. Ajouter des
    écouteurs
    

    View Slide

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);
    }
    }
    

    View Slide

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();
    // ...
    }
    }
    

    View Slide

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();
    }
    }
    

    View Slide

44. Enregistrer les
    écouteurs
    

    View Slide

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);
    

    View Slide

46. $article = new Article();
    $article->setDispatcher($dispatcher);
    $article->setTitle('AFUP Design Patterns');
    $article->setMarkdownContent(
    'Some **markdown** content'
    );
    $article->save();
    

    View Slide

47. Injection de dépendance
    

    View Slide

48. Single Responsability
    Open / Close principle
    Liskov substitution
    Interface segregation
    Dependency Injection
    

    View Slide

49. « Dependency Injection is
    where components are
    given their dependencies
    through their
    constructors, methods, or
    directly into fields. »
    http://picocontainer.codehaus.org/injection.html
    

    View Slide

50. Mauvaise
    Conception
    Initiale
    

    View Slide

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;
    }
    }
    }
    

    View Slide

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);
    

    View Slide

53. ça
    fonctionne !
    

    View Slide

54. Oui mais ?!!!
    

    View Slide

55. $transport = new SMTPTransport(
    'smtp.foo.com',
    1234,
    'mailer',
    'p$wD^'
    );
    

    View Slide

56. Je veux
    utiliser un
    transport
    différent…
    

    View Slide

57. Je veux
    configurer le
    SMTP en dev
    et en prod…
    

    View Slide

58. $logger = Logger::getInstance();
    $logger->log('Unable to...');
    $logger->logException($e);
    

    View Slide

59. Si le logger
    n’existe
    pas ?
    

    View Slide

60. Si je veux
    changer la
    configuration
    du logger?
    

    View Slide

61. Je veux tester
    mon code et
    je n’y arrive
    pas…
    

    View Slide

62. La Solution?
    

    View Slide

63. Injecter ses
    dépendances
    au Mailer
    

    View Slide

64. What ???
    

    View Slide

65. Injection
    par les
    propriétés
    

    View Slide

66. class Mailer
    {
    public $transport;
    public function send(Message $message)
    {
    try {
    $this->transport->send($message);
    } catch (TransportException $e) {
    // ...
    }
    }
    }
    

    View Slide

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);
    

    View Slide

68. Injection par
    constructeur
    

    View Slide

69. class Mailer
    {
    private $transport;
    function __construct(Transport $t)
    {
    $this->transport = $t;
    }
    }
    

    View Slide

70. $message = Message();
    $message->setFrom('me@example.com');
    // ...
    $transport = new SMTPTransport('...');
    $mailer = new Mailer($transport);
    $mailer->send($message);
    

    View Slide

71. Injection
    par un
    mutateur
    

    View Slide

72. class Mailer
    {
    private $logger;
    function setLogger(Logger $logger)
    {
    $this->logger = $logger;
    }
    }
    

    View Slide

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;
    }
    }
    }
    }
    

    View Slide

74. $message = Message();
    // ...
    $logger = new FileLogger('/to/dev.log');
    $transport = new SMTPTransport('...');
    $mailer = new Mailer($transport);
    $mailer->setLogger($logger);
    $mailer->send($message);
    

    View Slide

75. Découplage
    avec les
    interfaces
    

    View Slide

76. class Mailer
    {
    function __construct(TransportInterface $t)
    {
    $this->transport = $t;
    }
    function setLogger(LoggerInterface $logger)
    {
    $this->logger = $logger;
    }
    }
    

    View Slide

77. class SMTPTransport implements TransportInterface
    {
    }
    class MailTransport implements TransportInterface
    {
    }
    class NullTransport implements TransportInterface
    {
    }
    

    View Slide

78. Bénéfices
    vs
    Pertes ?!
    

    View Slide

79. Configurabilité
    Modularité
    Testabilité
    

    View Slide

80. Construction
    un peu plus
    Complexe
    

    View Slide

81. Service Locator
    

    View Slide

82. « Le patron service
    locator permet
    d’encapsuler les
    mécanismes
    d’obtention d’un
    service. »
    

    View Slide

83. # composer.json
    {
    "require": {
    "pimple/pimple": "1.0.*"
    }
    }
    

    View Slide

84. Global Configuration
    + Lazy Services
    = Container
    

    View Slide

85. Paramètres
    Globaux de
    Configuration
    

    View Slide

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*';
    

    View Slide

87. Enregistrer
    des services
    

    View Slide

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;
    });
    

    View Slide

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']
    );
    });
    

    View Slide

90. $pimple['mailer'] = $pimple->share(function ($c) {
    $mailer = new Mailer($c['mailer.transport']);
    if (isset($c['logger'])) {
    $mailer->setLogger($c['logger']);
    }
    return $mailer;
    });
    

    View Slide

91. Initialisation
    des services à
    la demande
    

    View Slide

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);
    

    View Slide

93. Pour aller
    plus loin!
    

    View Slide

94. DependencyInjection
    

    View Slide

95. View Slide