index.php

<?php

require_once 'Container.php';

class UserController
{
	public $repository;

	public function __construct(Repository $repository)
	{
		$this->repository = $repository;
	}

	public function getUser()
	{
		echo "Controller loaded...\n";
	}
}

class Db
{
	public function __construct()
	{
		echo "Db loaded...\n";
	}
}

class Model
{
	public function __construct(
		Config $config,

		Cache $cache
	) {
		$this->index();
	}

	public function index()
	{
		echo "Model loaded...\n";
	}
}

class Repository
{
	public $model;

	public function __construct(Model $model, Env $env)
	{
		$this->model = $model;
		$this->index();
	}

	public function index()
	{
		echo "Repository loaded...\n";
	}
}

class Config
{
	public function __construct(Env $env)
	{
		echo "Config loaded...\n";
	}
}

class Env
{
	public function __construct()
	{
		echo "Env loaded...\n";
	}
}

class Cache
{
	public function __construct()
	{
		echo "Cache loaded...\n";
	}
}

// create new container object
$container = new Container();

// get userController object and resolve all dependency
$user = $container->resolve('UserController');

$user->getUser();

smallContainer.php

<?php

class Container
{
	/**
	 * * Instantiate a concrete instance of the given type.
	 */
	public function resolve($concrete)
	{
		$reflector = new ReflectionClass($concrete);

		$constructor = $reflector->getConstructor();
		$dependencies = $constructor->getParameters();

		$instances = $this->getDependencies($dependencies);

		return $reflector->newInstanceArgs($instances);
	}

	/**
	 * Resolve the given type from the container.
	 */
	public function getDependencies($parameters = [])
	{
		$results = [];

		foreach ($parameters as $parameter) {
			$isClass = $parameter->getClass();

			if ($isClass) {
				$concrete = $parameter->name;
				$results[] = $this->resolve($concrete);
			} else {
				$results[] = $parameter->getDefaultValue();
			}
		}
		return $results;
	}
}