<?php
namespace Concrete\Core\Foundation\Service;
use \Concrete\Core\Application\Application;

class ProviderList {

	public function __construct(Application $app) {
		$this->app = $app;
	}

	/**
	 * Loads and registers a class ServiceProvider class.
	 * @param  string $class
	 * @return void
	 */
	public function registerProvider($class) {
		$this->createInstance($class)->register();
	}

	/**
	 * Class for creating an instance of a passed class string, override this to add extra functionality
	 *
	 * @param string $class The class name
	 * @return \Concrete\Core\Foundation\Service\Provider
	 */
	protected function createInstance($class)
	{
		return new $class($this->app);
	}

	/**
	 * Registers an array of service group classes.
	 * @param  array $groups
	 * @return void
	 */
	public function registerProviders($groups) {
		foreach($groups as $group) {
			$this->registerProvider($group);
		}
	}

	/**
	 * We are not allowed to serialize $this->app
	 */
	public function __sleep() {
		unset($this->app);
	}


}

<?php
namespace Concrete\Core\Foundation\Service;
use \Concrete\Core\Application\Application;

class ProviderList {

	public function __construct(Application $app) {
		$this->app = $app;
	}

	/**
	 * Loads and registers a class ServiceProvider class.
	 * @param  string $class
	 * @return void
	 */
	public function registerProvider($class) {
		$this->createInstance($class)->register();
	}

	/**
	 * Creates an instance of the passed class string, override this to change how providers are instantiated
	 *
	 * @param string $class The class name
	 * @return \Concrete\Core\Foundation\Service\Provider
	 */
	protected function createInstance($class)
	{
		return new $class($this->app);
	}

	/**
	 * Registers an array of service group classes.
	 * @param  array $groups
	 * @return void
	 */
	public function registerProviders($groups) {
		foreach($groups as $group) {
			$this->registerProvider($group);
		}
	}

	/**
	 * We are not allowed to serialize $this->app
	 */
	public function __sleep() {
		unset($this->app);
	}


}

Update createInstance documentation to be more clear
Docs: Update createInstance documentation to be more clear
