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IoC container - Dutch PHP Conference 2018

IoC container - Dutch PHP Conference 2018

Did you know your IoC container can do a whole lot more than just constructor injection? Besides that it is actually packed with features. Inflectors, resolving callbacks, aliasing, method invocation to name a few. In this talk you will learn how to leverage the power of a great container and service providers to write better, loosely coupled code. Well designed code put together by your IoC container will make your applications SOLID, modular, lean and decoupled from the framework!

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Hannes Van De Vreken

June 09, 2018
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Transcript

  1. IOC container @hannesvdvreken #dpc

  2. Hi, my name is Hannes.

  3. !

  4. IoC Container

  5. I O C

  6. International O C

  7. International Olympic C

  8. International Olympic Committee

  9. International Olympic Committee

  10. IoC Container

  11. IoC Container

  12. WHAT IS IOC? IoC == Inversion of Control

  13. WHAT IS IOC? class Service { public function __construct() {

    init(); } public function init() { $config = config(‘ftpsettings…’); $this->ftp = new FTP(…); } public function calculate(); }
  14. WHAT IS IOC? $service = $container->get(Service::class); $service->calculate();

  15. But first: Design patterns WHAT IS IOC?

  16. class Service { public function init() { // setup FTP

    } public function calculate() { // Get stuff from FTP. // Do calculations. // Return result. } } WHAT IS IOC?
  17. class Service { public function __construct(Ftp $ftp) { } public

    function calculate() { // Get stuff from FTP. // Do calculations. // Return result. } } WHAT IS IOC?
  18. class Service { public function __construct(Ftp $ftp) { } public

    function calculate() { // Get stuff from FTP. // Add caching to prevent hitting FTP over and over again // Do calculations. // Return result. } } WHAT IS IOC?
  19. class Service { public function __construct(Ftp $ftp) { } public

    function calculate() { // Get stuff from FTP. // Add caching to prevent hitting FTP over and over again // Log that FTP is accessed. // Do calculations. // Return result. } } WHAT IS IOC?
  20. class Service { public function __construct(Ftp $ftp) { } public

    function calculate() { // Get stuff from FTP. // Add caching to prevent hitting FTP over and over again // Log that FTP is accessed. // Do calculations. // Return result. } } WHAT IS IOC?
  21. class FtpStorage { public function __construct(Ftp $ftp) { $this->ftp =

    $ftp; } public function get($key) { // Get it. // Cache it. // Log it. // Return it. } } WHAT IS IOC?
  22. class Service { public function __construct(FtpStorage $storage) {
 $this->storage =

    $storage; } public function calculate() { $value = $this->storage->get($key); return $calculate($value); } } WHAT IS IOC?
  23. interface Storage { public function get($key); } WHAT IS IOC?

  24. class FtpStorage implements Storage { public function __construct(Ftp $ftp) {

    $this->ftp = $ftp; } public function get($key) { … } } WHAT IS IOC?
  25. class Service { public function __construct(Storage $storage) {
 $this->storage =

    $storage; } } WHAT IS IOC?
  26. class CacheDecorator implements Storage { public function __construct(Cache $cache, Storage

    $wrapped) {…} public function get($key) { return $this->cache->remember($key, 60, function () { return $this->wrapped->get($key); }); } } WHAT IS IOC?
  27. class LogDecorator implements Storage { public function __construct(LoggerInterface $log, Storage

    $wrapped) {…} public function get($key) { $this->log->info('Retrieved value for '.$key); return $this->wrapped->get($key); } } WHAT IS IOC?
  28. class FtpStorage implements Storage { public function __construct(Ftp $ftp) {

    $this->ftp = $ftp; } public function get($key) { // Get it and return it. } } WHAT IS IOC?
  29. FtpStorage Service depends on depends on Ftp WHAT IS IOC?

  30. FtpStorage implements <interface> Storage Service depends on depends on Ftp

    WHAT IS IOC?
  31. FtpStorage <interface> Storage CacheDecorator Service LogDecorator S3Storage WHAT IS IOC?

    implements depends on
  32. WHAT IS IOC? FtpStorage Service depends on depends on Ftp

    FtpStorage implements <interface> Storage Service depends on depends on Ftp
  33. new Service($ftp); WHAT IS IOC?

  34. new Service( new CacheDecorator( $cache, new LogDecorator( $logger, new FtpStorage(

    new Ftp($settings) ) ) ) ); WHAT IS IOC?
  35. $container->get(Service::class); 1) Make FtpStorage 2) Wrap it with LogDecorator 3)

    Wrap LogDecorator instance with CacheDecorator 4) New up Service with CacheDecorator instance. WHAT IS IOC?
  36. Dependency inversion: Interface + implementation Dependency injection: Injecting `Storage` into

    `Service` Inversion of Control: The container builds your objects and calls them WHAT IS IOC?
  37. Inversion of Control IoC container to the rescue WHAT IS

    IOC?
  38. Let the IoC container help you with Composition WHAT IS

    IOC?
  39. symfony/dependency-injection illuminate/container aura/di zendframework/zend-di pimple/pimple league/container … container-interop/container-interop psr/container (PSR-11)

    CONSTRUCTOR INJECTION
  40. None
  41. PSR-11 namespace Interop\Container; use Psr\Container\ContainerInterface as PsrContainer; interface ContainerInterface extends

    PsrContainer { … }
  42. PSR-11 namespace Psr\Container; interface ContainerInterface { public function get($id); public

    function has($id); }
  43. Automatic object resolution

  44. // League $container = new Container(); $container->delegate(new ReflectionContainer()); $listener =

    $container->get(SendInvoice::class); CONSTRUCTOR INJECTION
  45. Reflection CONSTRUCTOR INJECTION

  46. class SendInvoice { public function __construct(Mailer $mailer) { $this->mailer =

    $mailer; } public function listen(InvoiceGeneratedEvent $event) { … } } CONSTRUCTOR INJECTION
  47. Constructor injection CONSTRUCTOR INJECTION

  48. (new \ReflectionClass($classname)) ->getConstructor() ->getParameters(); CONSTRUCTOR INJECTION

  49. Recursively CONSTRUCTOR INJECTION

  50. Auto wiring: - Symfony - Zend - Laravel - league/container

    - … CONSTRUCTOR INJECTION
  51. But what if our code is SOLID… The container can’t

    construct interfaces? CONSTRUCTOR INJECTION
  52. Helping the container (not standardized)

  53. Situation 1: When <<interface>> is type hinted, resolve <<class>> instead

    REGISTRATION - BINDING
  54. Solution: Aliasing. REGISTRATION - BINDING

  55. $container->add(MailerInterface::class, function () { return $container->get(Mailer::class); }); REGISTRATION - BINDING

  56. // Symfony $container->setAlias(MailerInterface::class, Mailer::class); // Laravel $container->alias(MailerInterface::class, Mailer::class); REGISTRATION -

    BINDING
  57. Situation 2: When <<class>> has non-type hinted constructor arguments. REGISTRATION

    - BINDING
  58. Solution: Define dependencies. REGISTRATION - BINDING

  59. // League, et al. $container->add(Mailer::class, function () { return new

    Mailer($username, $password); }); REGISTRATION - BINDING
  60. // Symfony $container->register(Mailer::class) ->addArgument($username) ->addArgument($password); REGISTRATION - BINDING

  61. Situation 3: When <<class>> is type hinted, always return the

    exact same object. REGISTRATION - BINDING
  62. Example: Global state in a - Translator (user’s locale) -

    Entity Manager - Event dispatcher REGISTRATION - BINDING
  63. Solution: Sharing an instance. REGISTRATION - BINDING

  64. // League $container->share(EntityManagerInterface::class, function () { … }); // Laravel

    $container->singleton(EntityManagerInterface::class, function () { … }); // Symfony $container->register()->setShared(true); REGISTRATION - BINDING
  65. Situation 4: When different classes need a different object of

    the same interface. REGISTRATION - BINDING
  66. class PhotosController { public function __construct(FilesystemInterface $photos) { } }

    class FilesController { public function __construct(FilesystemInterface $files) { } } REGISTRATION - BINDING
  67. Solution: Contextual binding. REGISTRATION - BINDING

  68. // Laravel $container ->when(PhotosController::class) ->needs(FilesystemInterface::class) ->give('fs.photos'); REGISTRATION - CONTEXTUAL BINDING

  69. // Laravel $container->bind('fs.photos', function () {}); $container->bind('fs.files', function () {});

    REGISTRATION - BINDING
  70. // League $container->add('fs.photos', …); $container->add(PhotosController::class, function ( $fs = $container->get('fs.photos');

    return new PhotosController($fs); }); REGISTRATION - BINDING
  71. Situation 5: When resolving <<interface>>, do some setup. REGISTRATION -

    BINDING
  72. Example 1: When resolving the EntityManager, register some ModelListeners. REGISTRATION

    - BINDING
  73. Example 2: interface EnvironmentAware { public function setEnv($env); } trait

    EnvironmentAware { public function setEnv($env) { $this->env = $env; } } REGISTRATION - CONTAINER EVENTS
  74. Solution: Container events / inflection / hooks / … REGISTRATION

    - BINDING
  75. // League $container->inflector(EntityManager::class, function (EntityManager $em) { $em->getConfiguration() ->getEntityListenerResolver() ->register(new

    ModelListener()); } ); REGISTRATION - BINDING
  76. // Laravel $container->resolving(function (EnvironmentAware $object) { $object->setEnv(getenv('APP_ENV')); }); REGISTRATION -

    CONTAINER EVENTS
  77. Also useful for: - Quickly injecting stuff REGISTRATION - CONTAINER

    EVENTS
  78. interface CommandBusAware trait CommandBusAware interface EventDispatcherAware trait EventDispatcherAware REGISTRATION -

    CONTAINER EVENTS
  79. Also useful for: - Quickly injecting stuff REGISTRATION - CONTAINER

    EVENTS
  80. Also useful for: - Quickly injecting stuff - Injecting soft

    dependencies REGISTRATION - CONTAINER EVENTS
  81. $container—>resolving(function (Mailer $mailer) { $mailer->setQueueResolver(function () { return $container->make(Queue::class); });

    ); REGISTRATION - CONTAINER EVENTS
  82. Also useful for: - Quickly injecting stuff - Injecting soft

    dependencies REGISTRATION - CONTAINER EVENTS
  83. Also useful for: - Quickly injecting stuff - Injecting soft

    dependencies - Setting configurable values REGISTRATION - CONTAINER EVENTS
  84. $container->resolving(function (Validator) { $fileTypes = $container->get('config')->get(…) $validator->setAllowedFileTypes($fileTypes); ); REGISTRATION -

    CONTAINER EVENTS
  85. Where to put all this? REGISTRATION

  86. Symfony: - Configuration files - Factories REGISTRATION

  87. container-interop/service-provider Similar: - league/container - illuminate/container REGISTRATION

  88. Using a container

  89. Retrieving objects CALLING THE CONTAINER

  90. // Psr\Container\ContainerInterface $container->has('fs'); $container->get('fs'); CALLING THE CONTAINER

  91. Retrieving objects, with arguments CALLING THE CONTAINER

  92. // League $container->add('fs', function ($args) { // Use $args[0] to

    see what folder to use. }); $container->get('fs', ['images']); CALLING THE CONTAINER
  93. // League $container->add('fs.images', function () { return $container->get('fs', ['images']); });

    CALLING THE CONTAINER
  94. Calling functions, with resolved params CALLING THE CONTAINER

  95. // League & Laravel $container->call($closure); $container->call(function (Mailer $mailer) {}); $container->call([$listener,

    'handle']); $container->call('Listener::handle'); CALLING THE CONTAINER
  96. (new ReflectionFunction($callback)) ->getParameters(); CALLING THE CONTAINER

  97. // Laravel $func = $container->wrap('Listener@handle'); $func(); CALLING THE CONTAINER

  98. public function wrap($callback) { return function () { $this->call($callback); };

    } CALLING THE CONTAINER
  99. Tagging CALLING THE CONTAINER

  100. Beware: Tagging in Symfony != Tagging in Laravel CALLING THE

    CONTAINER
  101. // Laravel $container->tag('fs.images', 'filesystem'); $container->tag('fs.pdfs', 'filesystem'); $filesystems = $container->tagged('filesystem'); foreach

    ($filesystems as $filesystem) { … } CALLING THE CONTAINER
  102. Preferably only in - Factories - Event Dispatchers - Router

    - Command Bus - … CALLING THE CONTAINER
  103. Bonus

  104. Solving circular dependencies BONUS - CIRCULAR DEPENDENCIES

  105. $mailer = new Mailer(QueueInterface $queue); $queue = new Queue(MailerInterface $mailer);

    BONUS - CIRCULAR DEPENDENCIES
  106. $mailer = new Mailer(); $queue = new Queue(MailerInterface $mailer); $mailer->setQueueResolver($callable);

    BONUS CIRCULAR DEPENDENCIES
  107. $queue = $container->get(QueueInterface::class); // League $container->inflector(Mailer::class, function () { $mailer->setQueueResolver(function

    () { return $container->get(QueueInterface::class); }); }); BONUS CIRCULAR DEPENDENCIES
  108. Environment aware injection $container->bind(‘fs.photos’::class, function () { if (getenv(‘APP_ENV’) ===

    ‘integration’) { // Fill in memory adapter // with integration testing files
 } else { // Normal connection to S3. } }); BONUS - CIRCULAR DEPENDENCIES
  109. recap: Reflection Aliasing Soft dependencies Using container

  110. Thank you! @hannesvdvreken #dpc

  111. Time for questions. @hannesvdvreken #dpc