Dependency Injection 

Konzept 

Statt dem hier: 

public function __construct() { $this->dep1 = new Dependency1(); $this->dep2 = new Dependency2(); $this->dep3 = new Dependency3(); } 

… nimmt man das da: 

public function __construct( DependencyInterface1 $dep1, DependencyInterface2 $dep2, DependencyInterface3 $dep3) { $this->dep1 = $dep1; // ... } 

Das ist alles. 

Warum? 

Separation of concerns 

Testbarkeit 

Übersichtlichkeit 

Praxis 

Wer braucht schon ein Framework? 

class DoctrineEntityManagerBuilder { public static function build() { $config = new Configuration(); $config->setFoo("bar"); $connOpts = array( "driver" => "pdo_sqlite", "path" => "database.sqlite" ); return EntityManager::create( $connOpts, $config ); } } 

Wildwuchs vermeiden 

class DoctrineEntityManagerBuilder { private static $instance; public function build() { if (empty(static::$instance)) { // ... static::$instance = EntityManager::create( $connOpts, $config ); } return static::$instance; } } 

Symfony2 ServiceContainer 

Service? 

class DataImporter { private $em; Private $sourceUrl; public function __construct( EntityManager $em, $sourceUrl) { $this->em = $em; $this->sourceUrl = $sourceUrl; } public function import() { // ... } } 

DataImporter %dataimporter.source_url% 

class MyExtension extends Extension { public function load(...) { $loader = new XmlFileLoader(...); $loader->load('services.xml'); // Konfiguration auslesen // und in Container einfügen } public function getAlias() { return "my_extension"; } } 

class MyController extends Controller { public function importAction() { $importer = $this->get("dataimporter"); $importer->import(); // ... } } 

Fragen?