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<?php
/**
* @link http://www.yiiframework.com/
* @copyright Copyright (c) 2008 Yii Software LLC
* @license http://www.yiiframework.com/license/
*/
namespace yii\di;
use Psr\Container\ContainerInterface;
use yii\di\contracts\DependencyInterface;
use yii\di\exceptions\InvalidConfigException;
* Class Reference allows us to define a dependency to a service in the container in another service definition.
* For example:
* ```php
* [
* InterfaceA::class => ConcreteA::class,
* 'alternativeForA' => ConcreteB::class,
* Service1::class => [
* '__construct()' => [
* Reference::to('alternativeForA')
* ]
* ```
class Reference implements DependencyInterface
{
private $id;
private function __construct($id)
$this->id = $id;
}
public function getId(): string
return $this->id;
public static function to(string $id)
return new self($id);
* @param Container $container
public function resolve(ContainerInterface $container)
return $container->get($this->id);
* Restores class state after using `var_export()`.
*
* @param array $state
* @return self
* @throws InvalidConfigException when $state property does not contain `id` parameter
* @see var_export()
public static function __set_state($state)
if (!isset($state['id'])) {
throw new InvalidConfigException(
'Failed to instantiate class "Reference". Required parameter "id" is missing'
);
return new self($state['id']);
yiisoft /
di
