IoC container - Laracon EU 2016

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IOC container @hannesvdvreken Laracon EU 2016

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Hi, my name is Hannes.

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madewithlove.be !$%&'

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IoC Container

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I O C

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International O C

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International Olympic C

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International Olympic Committee

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International Olympic Committee

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WHAT IS IOC? IoC == Inversion of Control

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WHAT IS IOC? But first: Design patterns

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

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WHAT IS IOC? 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. } }

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

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WHAT IS IOC? class Service { public function __construct(FtpStorage $storage) {  $this->storage = $storage; } }

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WHAT IS IOC? interface Storage { public function get($key); }

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WHAT IS IOC? \ class FtpStorage implements Storage { public function __construct(Ftp $ftp) { $this->ftp = $ftp; } public function get($key) { … } }

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WHAT IS IOC? class Service { public function __construct(Storage $storage) {  $this->storage = $storage; } }

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WHAT IS IOC? new Service(new FtpStorage(new Ftp($settings)));

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WHAT IS IOC? Don’t create these instances yourself

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WHAT IS IOC? Inversion of Control IoC container to the rescue

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WHAT IS IOC? \ 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); }); } }

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WHAT IS IOC? \ 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); } }

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WHAT IS IOC? \ class FtpStorage implements Storage { public function __construct(Ftp $ftp) { $this->ftp = $ftp; } public function get($key) { // Get it and return it. } }

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WHAT IS IOC? FtpStorage implements Storage Service depends on depends on Ftp

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WHAT IS IOC? FtpStorage Storage CacheDecorator Service LogDecorator S3Storage implements depends on

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WHAT IS IOC? Dependency inversion: Interface + implementation Dependency injection: Injecting `Storage` into `Service` Inversion of Control: The container builds your objects and calls them

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WHAT IS IOC? $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.

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WHAT IS IOC? IoC container is here to help you with Composition

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CONSTRUCTOR INJECTION illuminate/container league/container symfony/dependency-injection aura/di … container-interop/container-interop

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Automatic constructor injection

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class SendInvoice { public function __construct(Mailer $mailer) { $this->mailer = $mailer; } public function listen(InvoiceGeneratedEvent $event) { … } }

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CONSTRUCTOR INJECTION Constructor injection

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$app->make(SendInvoice::class);

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CONSTRUCTOR INJECTION Reflection

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(new \ReflectionClass($class)) ->getConstructor() ->getParameters();

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CONSTRUCTOR INJECTION Recursively

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Helping the container

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REGISTRATION Service Providers

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class ServiceProvider { public function register() { … } public function boot(Dispatcher $events) }

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class ServiceProvider { public function register() {…} public function boot(Dispatcher $events) { … } }

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class ServiceProvider { protected $defer = true; public function register() {…} public function provides() { return [ Mailer::class, SwiftMailer::class, ]; } }

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REGISTRATION Register bindings in the register method

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REGISTRATION - BINDING $this->app->bind( MailerContract::class, SwiftMailer::class );

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REGISTRATION - BINDING $this->app->bind(Mailer::class, function () { $mailer = new SwiftMailer(); return new LogDecorator($mailer); });

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REGISTRATION - BINDING $this->app->singleton(Mailer::class, function () { … });

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REGISTRATION - BINDING $this->app->alias( Mailer::class, 'mailer' );

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REGISTRATION Bind a concretion for every interface

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REGISTRATION Bind everything with its class name

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REGISTRATION Unless you bind multiple versions

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REGISTRATION $this->app->bind('fs.photos', function () {}); $this->app->bind('fs.files', function () {});

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REGISTRATION - CONTEXTUAL BINDING Contextual binding

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REGISTRATION - CONTEXTUAL BINDING $this->app ->when(PhotosController::class) ->needs(FilesystemInterface::class) ->give('fs.photos');

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REGISTRATION - CONTEXTUAL BINDING No more DB::connection('db1')->table($table)->…;

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$this->app->bind('db.1', function () { return $this->app['db'] ->connection('db1'); }); $this->app ->when(EventListener::class) ->needs(ConnectionInterface::class) ->give('db.1');

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Inflection REGISTRATION - CONTAINER EVENTS

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REGISTRATION - CONTAINER EVENTS Inflection (aka “container events”)

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REGISTRATION - CONTAINER EVENTS $this->app->resolving( function (Foo $foo) {…} );

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use App\Contracts\EnvironmentAware; $this->app->resolving( function (EnvironmentAware $object) { $object->setEnv( $this->app->environment() ); } );

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interface EnvironmentAware { public function setEnv($env); }

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trait EnvironmentAware { public function setEnv($env) { $this->env = $env; } private function isEnv($envs): bool { return in_array($this->env, (array) $envs); } }

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REGISTRATION - CONTAINER EVENTS Method injection

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

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REGISTRATION - CONTAINER EVENTS interface CommandBusAware trait CommandBusAware interface EventDispatcherAware trait EventDispatcherAware

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

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

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$this->app->resolving(function (Mailer $mailer) { $mailer->setQueueResolver(function () { return $this->app->make(Queue::class); }); );

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

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REGISTRATION - CONTAINER EVENTS Also useful for: - Quickly injecting stuff - Injecting soft dependencies - Setting configurable values

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$this->app->resolving(function (Validator) { $fileTypes = $app['config']->get(…) $validator->setAllowedFileTypes($fileTypes); );

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Using the container

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CALLING THE CONTAINER Preferably only for - Factories - Event Dispatchers - Router - Command Bus

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$this->app->make('fs'); $this->app->make('fs', […]); $this->app->bind( 'fs', function ($app, $args) {…} );

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$this->app->call(function (Mailer $mailer) {}); $this->app->call([$listener, 'handle']); $this->app->call('Listener::handle'); $this->app->call('Listener@handle');

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$func = $this->app->wrap('Listener@handle'); $func();

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

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Bonus

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BONUS - SOFT DEPENDENCIES Solving circular dependencies

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BONUS - CIRCULAR DEPENDENCIES Solving circular dependencies

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BONUS - CIRCULAR DEPENDENCIES $mailer = new Mailer(QueueInterface $queue); $queue = new Queue(MailerInterface $mailer);

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BONUS - CIRCULAR DEPENDENCIES $mailer = new Mailer(); $queue = new Queue(MailerInterface $mailer); $mailer->setQueueResolver(function () { return $this->app->make('queue'); });

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BONUS - NOT SUPPORTED Contextual binding for methods (unsupported)

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BONUS - METHOD LEVEL CONTEXTUAL BINDING $this->app—>when('FooController@store') ->needs(QueueContract::class) ->give('queue.redis'); https:/ /github.com/laravel/framework/pull/12183