<?php
 
class SomeComponent
{
  public function doSomething()
  {
  }
}
 
class App
{
  public function __construct(SomeComponent $theComponent)
  {
    $this->theComponent = $theComponent;
  }
 
  public function run()
  {
    $this->theComponent->doSomething();
  }
}
 
class DIContainer{
  public function get($className)  {
    switch ($className) {
      case SomeComponent::class:
        return new SomeComponent;
      case App::class:
        return new App($this->get(SomeComponent::class));
      default:
        throw new Exception;
    }
  }
}
 
$DIContainer = new DIContainer();
$app = $DIContainer->get(App::class);
$app->run();

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