IoC container - PHP CE 2017

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