IoC container - Confoo Montreal 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!

Transcript

1. IOC container @hannesvdvreken #confoo
2. Hi, my name is Hannes.
3. !
6. IoC Container
7. I O C
8. International O C
9. International Olympic C
10. International Olympic Committee
11. International Olympic Committee
12. IoC Container
13. IoC Container
14. WHAT IS IOC? IoC == Inversion of Control
15. WHAT IS IOC? class Service { public function __construct() { init(); } public function init() { $config = config(‘ftpsettings…’); $this->ftp = new FTP(…); } public function calculate(); }
16. WHAT IS IOC? $service = $container->get(Service::class); $service->calculate();
17. But first: Design patterns WHAT IS IOC?
18. class Service { public function calculate() { // Get stuff from FTP. // Do calculations. // Return result. } } WHAT IS IOC?
19. class Service { public function __construct(Ftp $ftp) { } public function calculate() { // Get stuff from FTP. // 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 // Do calculations. // Return result. } } WHAT IS IOC?
21. 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?
22. 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?
23. 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?
24. class Service { public function __construct(FtpStorage $storage) {
 $this->storage = $storage; } public function calculate() { $value = $this->storage->get($key); return $calculate($value); } } WHAT IS IOC?
25. interface Storage { public function get($key); } WHAT IS IOC?
26. class FtpStorage implements Storage { public function __construct(Ftp $ftp) { $this->ftp = $ftp; } public function get($key) { … } } WHAT IS IOC?
27. class Service { public function __construct(Storage $storage) {
 $this->storage = $storage; } } WHAT IS IOC?
28. class CacheDecorator implements Storage { public function __construct(Cache $cache, Storage $storage) {…} public function get($key) { return $this->cache->remember($key, 60, function () { return $this->storage->get($key); }); } } WHAT IS IOC?
29. class LogDecorator implements Storage { public function __construct(LoggerInterface $log, Storage $storage) {…} public function get($key) { $this->log->info('Retrieved value for '.$key); return $this->storage->get($key); } } WHAT IS IOC?
30. class FtpStorage implements Storage { public function __construct(Ftp $ftp) { $this->ftp = $ftp; } public function get($key) { // Get it and return it. } } WHAT IS IOC?
31. FtpStorage Service depends on depends on Ftp WHAT IS IOC?
32. FtpStorage implements <interface> Storage Service depends on depends on Ftp WHAT IS IOC?
33. FtpStorage <interface> Storage CacheDecorator Service LogDecorator S3Storage WHAT IS IOC? implements depends on
34. WHAT IS IOC? FtpStorage Service depends on depends on Ftp FtpStorage implements <interface> Storage Service depends on depends on Ftp
35. Dependency inversion: Interface + implementation Dependency injection: Injecting `Storage` into `Service` Inversion of Control: The container builds your objects and calls them WHAT IS IOC?
36. new Service($ftp); WHAT IS IOC?
37. new Service( new CacheDecorator( $cache, new LogDecorator( $logger, new FtpStorage( new Ftp($settings) ) ) ) ); WHAT IS IOC?
38. $container->get(Service::class); 1) Make FtpStorage 2) Wrap it with LogDecorator 3) Wrap LogDecorator instance with CacheDecorator 4) New up Service with CacheDecorator instance. WHAT IS IOC?
39. Inversion of Control IoC container to the rescue WHAT IS IOC?
40. Let the IoC container help you with Composition WHAT IS IOC?
41. symfony/dependency-injection illuminate/container aura/di zendframework/zend-di pimple/pimple league/container … container-interop/container-interop psr/container (PSR-11) CONSTRUCTOR INJECTION
43. PSR-11 namespace Interop\Container; use Psr\Container\ContainerInterface as PsrContainer; interface ContainerInterface extends PsrContainer { … }
44. PSR-11 namespace Psr\Container; interface ContainerInterface { public function get($id); public function has($id); }
45. Using the container
46. CONSTRUCTOR INJECTION $service = $container->get(Service::class);
47. Automatic object resolution
48. class SendInvoice { public function __construct(Mailer $mailer) { $this->mailer = $mailer; } public function listen(InvoiceGeneratedEvent $event) { … } } CONSTRUCTOR INJECTION
49. Constructor injection CONSTRUCTOR INJECTION
50. $listener = $container->get(SendInvoice::class); CONSTRUCTOR INJECTION
51. // League $container = new Container(); $container->delegate(new ReflectionContainer()); $listener = $container->get(SendInvoice::class); CONSTRUCTOR INJECTION
52. Reflection CONSTRUCTOR INJECTION
53. (new \ReflectionClass($class)) ->getConstructor() ->getParameters(); CONSTRUCTOR INJECTION
54. Recursively CONSTRUCTOR INJECTION
55. Auto wiring: - Symfony - Zend - Laravel - league/container - … CONSTRUCTOR INJECTION
56. But what if our code is SOLID… The container can’t construct interfaces? CONSTRUCTOR INJECTION
57. Helping the container (not standardized)
58. Situation 1: When <<interface>> is type hinted, resolve <<class>> instead REGISTRATION - BINDING
59. Solution: Aliasing. REGISTRATION - BINDING
60. $container->add(MailerInterface::class, function () { return $container->get(Mailer::class); }); REGISTRATION - BINDING
61. // Symfony $container->setAlias(MailerInterface::class, Mailer::class); // Laravel $container->alias(MailerInterface::class, Mailer::class); REGISTRATION - BINDING
62. Situation 2: When <<class>> has non-type hinted constructor arguments. REGISTRATION - BINDING
63. Solution: Define dependencies. REGISTRATION - BINDING
64. // League, et al. $container->add(Mailer::class, function () { return new Mailer($username, $password); }); REGISTRATION - BINDING
65. // Symfony $container->register(Mailer::class) ->addArgument($username) ->addArgument($password); REGISTRATION - BINDING
66. Situation 3: When <<class>> is type hinted, always return the exact same object. REGISTRATION - BINDING
67. Example: Global state in a - Translator (user’s locale) - Entity Manager - Event dispatcher REGISTRATION - BINDING
68. Solution: Sharing an instance. REGISTRATION - BINDING
69. // League $container->share(EntityManagerInterface::class, function () { … }); // Laravel $container->singleton(EntityManagerInterface::class, function () { … }); // Symfony $container->register()->setShared(true); REGISTRATION - BINDING
70. Situation 4: When different classes need a different object of the same interface. REGISTRATION - BINDING
71. class PhotosController { public function __construct(FilesystemInterface $photos) { } } class FilesController { public function __construct(FilesystemInterface $files) { } } REGISTRATION - BINDING
72. Solution: Contextual binding. REGISTRATION - BINDING
73. // Laravel $container->bind('fs.photos', function () {}); $container->bind('fs.files', function () {}); REGISTRATION - BINDING
74. // Laravel $container ->when(PhotosController::class) ->needs(FilesystemInterface::class) ->give('fs.photos'); REGISTRATION - CONTEXTUAL BINDING
75. Situation 5: When resolving <<interface>>, do some setup. REGISTRATION - BINDING
76. Example 1: When resolving the EntityManager, register some ModelListeners. REGISTRATION - BINDING
77. Example 2: interface EnvironmentAware { public function setEnv($env); } trait EnvironmentAware { public function setEnv($env) { $this->env = $env; } } REGISTRATION - CONTAINER EVENTS
78. Solution: Container events / inflection / hooks / … REGISTRATION - BINDING
79. // League $container->inflector(EntityManager::class, function (EntityManager $em) { $em->getConfiguration() ->getEntityListenerResolver() ->register(new ModelListener()); } ); REGISTRATION - BINDING
80. // Laravel $container->resolving(function (EnvironmentAware $object) { $object->setEnv(getenv('APP_ENV')); }); REGISTRATION - CONTAINER EVENTS
81. Also useful for: - Quickly injecting stuff REGISTRATION - CONTAINER EVENTS
82. interface CommandBusAware trait CommandBusAware interface EventDispatcherAware trait EventDispatcherAware REGISTRATION - CONTAINER EVENTS
83. Also useful for: - Quickly injecting stuff REGISTRATION - CONTAINER EVENTS
84. Also useful for: - Quickly injecting stuff - Injecting soft dependencies REGISTRATION - CONTAINER EVENTS
85. $container—>resolving(function (Mailer $mailer) { $mailer->setQueueResolver(function () { return $container->make(Queue::class); }); ); REGISTRATION - CONTAINER EVENTS
86. Also useful for: - Quickly injecting stuff - Injecting soft dependencies REGISTRATION - CONTAINER EVENTS
87. Also useful for: - Quickly injecting stuff - Injecting soft dependencies - Setting configurable values REGISTRATION - CONTAINER EVENTS
88. $container->resolving(function (Validator) { $fileTypes = $container->get('config')->get(…) $validator->setAllowedFileTypes($fileTypes); ); REGISTRATION - CONTAINER EVENTS
89. Where to put all this? REGISTRATION
90. Symfony: - Configuration files - Factories REGISTRATION
91. container-interop/service-provider Similar: - league/container - illuminate/container REGISTRATION
92. Using a container
93. Retrieving objects CALLING THE CONTAINER
94. // Psr\Container\ContainerInterface $container->has('fs'); $container->get('fs'); CALLING THE CONTAINER
95. Retrieving objects, with arguments CALLING THE CONTAINER
96. // League $container->add('fs', function ($args) { // Use $args[0] to see what folder to use. }); $container->get('fs', ['images']); CALLING THE CONTAINER
97. // League $container->add('fs.images', function () { return $container->get('fs', ['images']); }); CALLING THE CONTAINER
98. Calling functions, with resolved params CALLING THE CONTAINER
99. // League & Laravel $container->call($closure); $container->call(function (Mailer $mailer) {}); $container->call([$listener, 'handle']); $container->call('Listener::handle'); CALLING THE CONTAINER
100. (new ReflectionFunction($callback)) ->getParameters(); CALLING THE CONTAINER
101. // Laravel $func = $container->wrap('Listener@handle'); $func(); CALLING THE CONTAINER
102. public function wrap($callback) { return function () { $this->call($callback); }; } CALLING THE CONTAINER
103. Tagging CALLING THE CONTAINER
104. Beware: Tagging in Symfony != Tagging in Laravel CALLING THE CONTAINER
105. // Laravel $container->tag('fs.images', 'filesystem'); $container->tag('fs.pdfs', 'filesystem'); $filesystems = $container->tagged('filesystem'); foreach ($filesystems as $filesystem) { … } CALLING THE CONTAINER
106. Preferably only in - Factories - Event Dispatchers - Router - Command Bus - … CALLING THE CONTAINER
107. Bonus
108. Solving circular dependencies BONUS - CIRCULAR DEPENDENCIES
109. $mailer = new Mailer(QueueInterface $queue); $queue = new Queue(MailerInterface $mailer); BONUS - CIRCULAR DEPENDENCIES
110. $mailer = new Mailer(); $queue = new Queue(MailerInterface $mailer); $mailer->setQueueResolver($callable); BONUS CIRCULAR DEPENDENCIES
111. $queue = $container->get(QueueInterface::class); // League $container->inflector(Mailer::class, function () { $mailer->setQueueResolver(function () { return $container->get(QueueInterface::class); }); }); BONUS CIRCULAR DEPENDENCIES
112. 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
113. recap: Reflection Aliasing Soft dependencies Using container
114. Thank you! @hannesvdvreken #confoo
115. Time for questions. @hannesvdvreken #confoo
117. • https://getstream.io/try-the-api REFERENCES