Hydrator example with object type-hint and return-type

container.php

<?php
interface ServiceContainer {
  /**
   * Set service definition
   * @param string $id Service identifier
   * @param object $service Service object or closure
   */
  public function set(string $id, object $service);
  /**
   * Retrieve service object from container
   * @param string $id Service identifier
   * @return
   */
  public function get(string $id) : object;
}

class Container implements ServiceContainer {
  /** @var object[] */
  private $services = [];
  /**
   * {@inheritdoc}
   */
  public function set(string $id, object $service) {
    $this->services[$id] = $service;
  }
    /**
   * {@inheritdoc}
   */
  public function get(string $id) : object {
    // some assertion
    $service = $this->services[$id];
    if ($service instanceof Closure) {
      return $service();
    }

    return $service;
  }
}

$container = new Container();
$container->set('std', new stdClass());
$container->set('lazy', function () use ($container) : object {
  return $container->get('std');
});

var_dump($container->get('std'), $container->get('lazy'));

hydrator.php

<?php

interface Hydration {
  /**
   * Hydrate an object by populating data
   * @param array $data Data to populate
   * @param object $object Object to populate data
   * @return object
   */
  public function hydrate(array $data, object $object) : object;
}

interface Extraction {
  /**
   * Extract values from an object
   * @param object $object Object to extract data from
   * @return array
   */
  public function extract(object $object) : array;
}

class Hydrator implements Hydration, Extraction {
  /**
   * {@inheritdoc}
   */
  public function hydrate(array $data, object $object) : object {
    // hydration implementation without need for `is_object` validation
  }
  /**
   * {@inheritdoc}
   */
  public function extract(object $object) : array {
    // extraction validation without need for `is_object` validation
  }
}