IoC container - CODEid Odessa 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 @laravelliveuk IOC container Hannes Van De Vreken
2. Hi, my name is Hannes.
3. !
4. IoC Container
5. IoC Container
6. I O C
7. International O C
8. International Olympic C
9. International Olympic Committee
10. International Olympic Committee
11. IoC Container
12. IoC Container
13. IoC Container
14. WHAT IS IOC? IoC == Inversion of Control
15. WHAT IS IOC? $service = new Service(); $service->calculate(); $service = $container->get(Service::class); $service->calculate();
16. WHAT IS IOC? class Service { public function __construct() { init(); } public function init() { $config = config(‘ftpsettings…’); $this->ftp = new FTP(…); } public function calculate() {…} }
17. But first: Refresh your knowledge of Design patterns WHAT IS IOC?
18. class Service { public function init() { // setup FTP } 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 = $ftp; } public function get($filename) { // 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); // Do calculations. // Return result. } } WHAT IS IOC?
25. interface Storage { public function get($filename); } WHAT IS IOC?
26. class FtpStorage implements Storage { public function __construct(Ftp $ftp) { $this->ftp = $ftp; } public function get($filename) { … } } WHAT IS IOC?
27. class Service { public function __construct(FtpStorage $storage) {
 $this->storage = $storage; } public function calculate() { $value = $this->storage->get($key); // Do calculations. // Return result. } } WHAT IS IOC?
28. class Service { public function __construct(Storage $storage) {
 $this->storage = $storage; } public function calculate() { $value = $this->storage->get($key); // Do calculations. // Return result. } } WHAT IS IOC?
29. class FtpStorage { public function __construct(Ftp $ftp) { $this->ftp = $ftp; } public function get($filename) { // Get it. // Cache it. // Log it. // Return it. } } WHAT IS IOC?
30. 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?
31. 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?
32. class FtpStorage { public function __construct(Ftp $ftp) { $this->ftp = $ftp; } public function get($filename) { // Get it. // Cache it. // Log it. // Return it. } } WHAT IS IOC?
33. class FtpStorage { public function __construct(Ftp $ftp) { $this->ftp = $ftp; } public function get($filename) { // Get it. // Return it. } } WHAT IS IOC?
34. FtpStorage Service depends on depends on Ftp WHAT IS IOC?
35. FtpStorage Service depends on Ftp WHAT IS IOC? implements <interface> Storage depends on
36. Service WHAT IS IOC? implements <interface> Storage depends on FtpStorage CacheDecorator LogDecorator S3Storage
37. WHAT IS IOC? FtpStorage implements <interface> Storage Service depends on depends on Ftp FtpStorage ervice depends on depends on Ftp
38. $service = new Service(); WHAT IS IOC?
39. $service = new Service( new CacheDecorator( $cache, new LogDecorator( $logger, new FtpStorage( new Ftp($settings) ) ) ) ); WHAT IS IOC?
40. $container->get(Service::class); 1) Make FtpStorage 2) Wrap it with LogDecorator 3) Wrap LogDecorator instance with CacheDecorator 4) New up Service with CacheDecorator instance. WHAT IS IOC?
41. Dependency inversion: Interface + implementation Dependency injection: Injecting `Storage` into `Service` Inversion of Control: The container builds your objects and calls them WHAT IS IOC?
42. Inversion of Control IoC container to the rescue WHAT IS IOC?
43. Let the IoC container help you with Composition WHAT IS IOC?
44. symfony/dependency-injection illuminate/container aura/di zendframework/zend-di pimple/pimple league/container bitexpert/disco … container-interop/container-interop psr/container (PSR-11) CONSTRUCTOR INJECTION
45. PSR-11 namespace Psr\Container; interface ContainerInterface { public function get($id); public function has($id); }
47. Automatic object resolution
48. $listener = $container->get(SendInvoice::class); $listener->listen($event); CONSTRUCTOR INJECTION
49. Reflection CONSTRUCTOR INJECTION
50. class SendInvoice { public function __construct(Mailer $mailer) { $this->mailer = $mailer; } public function listen(InvoiceGeneratedEvent $event) { … } } CONSTRUCTOR INJECTION
51. Constructor injection CONSTRUCTOR INJECTION
52. (new \ReflectionClass($classname)) ->getConstructor() ->getParameters(); CONSTRUCTOR INJECTION
53. Recursively CONSTRUCTOR INJECTION
54. CONSTRUCTOR INJECTION SendInvoice ➡ Mailer ➡ SMTP
55. Auto wiring: - Laravel - Symfony - Zend - league/container - … CONSTRUCTOR INJECTION
56. But what if our code depends on interfaces… The container can’t construct interfaces? CONSTRUCTOR INJECTION
57. Helping the container
58. Situation 1: When <<interface>> is type hinted, resolve <<class>> instead REGISTRATION - BINDING
59. Solution: Aliasing. REGISTRATION - BINDING
60. // Laravel $container->alias(MailerInterface::class, Mailer::class); REGISTRATION - BINDING
61. // Laravel $container->bind(MailerInterface::class, function () { return $container->get(Mailer::class); }); REGISTRATION - BINDING
62. // The PHP League $container->add(MailerInterface::class, Mailer::class); REGISTRATION - BINDING
63. Situation 2: When <<class>> has non-type hinted constructor arguments. REGISTRATION - BINDING
64. class Mailer { /** * @param string $username * @param string $password */ public function construct($username, $password) {…} } REGISTRATION - BINDING
65. Solution: Define explicitly. REGISTRATION - BINDING
66. // Laravel $container->bind(Mailer::class, function () { return new Mailer($username, $password); }); REGISTRATION - BINDING
67. // Symfony $container->register(Mailer::class) ->addArgument($username) ->addArgument($password); REGISTRATION - BINDING
68. // The PHP League $container->add(Mailer::class) ->addArgument($username) ->addArgument($password); REGISTRATION - BINDING
69. Situation 3: When <<class>> is type hinted, always return the exact same object. REGISTRATION - BINDING
70. Example: Global state in a - Translator (user’s locale) - Entity Manager - Event dispatcher REGISTRATION - BINDING
71. Solution: Sharing an instance. REGISTRATION - BINDING
72. // Laravel $container->singleton(EntityManagerInterface::class, function () … }); $container->bind($key, $function, true); REGISTRATION - BINDING
73. // Symfony $container->register(EntityManager::class)->setShared(false); REGISTRATION - BINDING
74. // The PHP League $container->add(EntityManager::class)->setShared(); $container->share(EntityManager::class); REGISTRATION - BINDING
75. Situation 4: When different classes need a different object of the same interface. REGISTRATION - BINDING
76. class PhotosController { public function __construct(FilesystemInterface $photos) { } } class FilesController { public function __construct(FilesystemInterface $files) { } } REGISTRATION - BINDING
77. Solution: Contextual binding. REGISTRATION - BINDING
78. // Laravel $container ->when(PhotosController::class) ->needs(FilesystemInterface::class) ->give(‘fs.photos'); $container->bind('fs.photos', function () {}); $container->bind('fs.files', function () {}); REGISTRATION - CONTEXTUAL BINDING
79. // Laravel $container->bind('fs.photos', …); $container->bind(PhotosController::class, function $fs = $container->get('fs.photos'); return new PhotosController($fs); }); REGISTRATION - BINDING
80. // The PHP League $container->add('fs.photos', …); $container->add(PhotosController::class, function ( $fs = $container->get('fs.photos'); return new PhotosController($fs); }); REGISTRATION - BINDING
81. Situation 5: When resolving <<interface>>, do some setup. REGISTRATION - BINDING
82. Example 1: When resolving the EntityManager, register some ModelListeners. REGISTRATION - BINDING
83. Example 2: interface EnvironmentAware { public function setEnv($env); } trait EnvironmentAware { public function setEnv($env) { $this->env = $env; } } REGISTRATION - CONTAINER EVENTS
84. Solution: Container events / inflection / hooks / … REGISTRATION - BINDING
85. // Laravel $container->resolving(function (EnvironmentAware $object) { $object->setEnv(app()->environment()); }); REGISTRATION - CONTAINER EVENTS
86. // The PHP League $container->inflector(EnvironmentAware::class) ->invokeMethod(‘setenv’, [app()->environment()]); REGISTRATION - CONTAINER EVENTS
87. Also useful for: - Quickly injecting stuff REGISTRATION - CONTAINER EVENTS
88. interface CommandBusAware trait CommandBusAware interface EventDispatcherAware trait EventDispatcherAware REGISTRATION - CONTAINER EVENTS
89. Also useful for: - Quickly injecting stuff REGISTRATION - CONTAINER EVENTS
90. Also useful for: - Quickly injecting stuff - Injecting soft dependencies REGISTRATION - CONTAINER EVENTS
91. $container—>resolving(function (Mailer $mailer) { $mailer->setQueueResolver(function () { return $container->get(Queue::class); }); ); REGISTRATION - CONTAINER EVENTS
93. Also useful for: - Quickly injecting stuff - Injecting soft dependencies REGISTRATION - CONTAINER EVENTS
94. Also useful for: - Quickly injecting stuff - Injecting soft dependencies - Setting configurable values REGISTRATION - CONTAINER EVENTS
95. $container->resolving(function (Validator $validator) { $fileTypes = $container->get('config')->get(…) $validator->setAllowedFileTypes($fileTypes); ); REGISTRATION - CONTAINER EVENTS
96. Where to put all this? REGISTRATION
97. Service Providers! REGISTRATION
98. REGISTRATION public function register() { // Bindings } public function boot() { // Macros, extensions, container events, … }
99. REGISTRATION public function boot(View $view) { $view->composer(…); }
100. REGISTRATION // The PHP League $container->addServiceProvider(AppServiceProvider::class);
101. Using a container
102. Retrieving objects CALLING THE CONTAINER
103. // Psr\Container\ContainerInterface $container->has('fs'); $container->get('fs'); CALLING THE CONTAINER
104. Retrieving objects, with arguments CALLING THE CONTAINER
105. // Laravel $container->bind(‘fs', function ($args) { // Use $args[0] to see what folder to use. }); $container->get('fs', [‘images’]); CALLING THE CONTAINER
106. // Laravel $container->bind(‘fs', function ($args) { // Use $args[0] to see what folder to use. }); $container->get('fs', [‘images']); $container->bind('fs.images', function () { return $container->get('fs', ['images']); CALLING THE CONTAINER
107. Calling functions, with resolved params CALLING THE CONTAINER
108. // Laravel $container->call($closure); $container->call(function (Mailer $mailer) {}); $container->call([$listener, 'handle']); $container->call(‘Listener::handle’); CALLING THE CONTAINER
109. // Laravel $container->call($closure); $container->call(function (Mailer $mailer) {}); $container->call([$listener, 'handle']); $container->call(‘Listener::handle’); $container->call(‘Listener@handle'); CALLING THE CONTAINER
110. (new ReflectionFunction($callback)) ->getParameters(); CALLING THE CONTAINER
111. // Laravel $func = $container->wrap('Listener@handle'); $func(); CALLING THE CONTAINER
112. public function wrap($callback) { return function () { return $this->call($callback); }; } CALLING THE CONTAINER
113. Tagging CALLING THE CONTAINER
114. // Laravel $container->tag('fs.images', 'filesystem'); $container->tag('fs.pdfs', 'filesystem'); $filesystems = $container->tagged('filesystem'); foreach ($filesystems as $filesystem) { … } CALLING THE CONTAINER
115. // Laravel $container->tag(‘tool-1.dispatcher’, 'dispatcher'); $container->tag(‘tool-2.dispatcher’, 'dispatcher'); $dispatchers = $container->tagged(‘dispatcher'); foreach ($dispatchers as $dispatcher) { $listener->delegate($dispatcher); } CALLING THE CONTAINER
116. // The PHP League $container->add(‘fs.images’)->addTag(‘filesystems') $container->tag(‘fs.pdfs’)->addTag(‘filesystems'); $filesystems = $container->get(‘filesystems'); foreach ($filesystems as $filesystem) { … } CALLING THE CONTAINER
117. When to inject the container?
118. Preferably only in - Event Dispatchers - Router - Command Bus - Factories - … CALLING THE CONTAINER
119. Bonus
120. Solving circular dependencies BONUS - CIRCULAR DEPENDENCIES
121. $mailer = new Mailer(QueueInterface $queue); $queue = new Queue(MailerInterface $mailer); BONUS - CIRCULAR DEPENDENCIES
122. $mailer = new Mailer(); $queue = new Queue(MailerInterface $mailer); $mailer->setQueueResolver($callable); BONUS - CIRCULAR DEPENDENCIES
123. // Laravel $queue = $container->get(QueueInterface::class); $container->resolving(function (Mailer $mailer) { $mailer->setQueueResolver(function () { return $container->get(QueueInterface::class); }); }); BONUS - CIRCULAR DEPENDENCIES
124. Environment aware injection // Laravel $container->bind(‘fs.photos’, function () { if (getenv(‘APP_ENV’) === ‘integration’) { // Fill in memory adapter // with integration testing files
 } else { // Normal connection to S3. } }); BONUS
125. recap: Reflection Aliasing Soft dependencies Using container
126. Thank you! @hannesvdvreken @laravelliveuk Thank you @hannesvdvreken
127. Time for questions. @hannesvdvreken @laravelliveuk Time for questions @hannesvdvreken