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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!

Hannes Van De Vreken

June 09, 2018
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  1. !

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

    init(); } public function init() { $config = config(‘ftpsettings…’); $this->ftp = new FTP(…); } public function calculate(); }
  3. class Service { public function init() { // setup FTP

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

    function calculate() { // Get stuff from FTP. // Do calculations. // Return result. } } WHAT IS IOC?
  5. 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?
  6. 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?
  7. 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?
  8. 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?
  9. class Service { public function __construct(FtpStorage $storage) {
 $this->storage =

    $storage; } public function calculate() { $value = $this->storage->get($key); return $calculate($value); } } WHAT IS IOC?
  10. class FtpStorage implements Storage { public function __construct(Ftp $ftp) {

    $this->ftp = $ftp; } public function get($key) { … } } WHAT IS IOC?
  11. 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?
  12. 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?
  13. class FtpStorage implements Storage { public function __construct(Ftp $ftp) {

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

    FtpStorage implements <interface> Storage Service depends on depends on Ftp
  15. $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?
  16. Dependency inversion: Interface + implementation Dependency injection: Injecting `Storage` into

    `Service` Inversion of Control: The container builds your objects and calls them WHAT IS IOC?
  17. class SendInvoice { public function __construct(Mailer $mailer) { $this->mailer =

    $mailer; } public function listen(InvoiceGeneratedEvent $event) { … } } CONSTRUCTOR INJECTION
  18. But what if our code is SOLID… The container can’t

    construct interfaces? CONSTRUCTOR INJECTION
  19. // League, et al. $container->add(Mailer::class, function () { return new

    Mailer($username, $password); }); REGISTRATION - BINDING
  20. Situation 3: When <<class>> is type hinted, always return the

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

    Entity Manager - Event dispatcher REGISTRATION - BINDING
  22. // League $container->share(EntityManagerInterface::class, function () { … }); // Laravel

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

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

    class FilesController { public function __construct(FilesystemInterface $files) { } } REGISTRATION - BINDING
  25. Example 2: interface EnvironmentAware { public function setEnv($env); } trait

    EnvironmentAware { public function setEnv($env) { $this->env = $env; } } REGISTRATION - CONTAINER EVENTS
  26. Also useful for: - Quickly injecting stuff - Injecting soft

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

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

    dependencies - Setting configurable values REGISTRATION - CONTAINER EVENTS
  29. // League $container->add('fs', function ($args) { // Use $args[0] to

    see what folder to use. }); $container->get('fs', ['images']); CALLING THE CONTAINER
  30. Preferably only in - Factories - Event Dispatchers - Router

    - Command Bus - … CALLING THE CONTAINER
  31. 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