Creating URL for an external route in Zend Framework 2

In case anyone wondered how I resolved this issue, I put the url inside the application config and wrote a view&controller helper to retrieve it

module.config.php:

// ...

'view_helpers' => array(
    'invokables' => array(
        'externalUrl' => 'MyModule\Helper\ExternalUrlHelper',
    ),
),

'controller_plugins' => array(
    'invokables' => array(
        'externalUrl' => 'MyModule\Helper\ExternalUrlHelper',
    )
),

// ...
'external_urls' => array(
    'home' => 'http://some-other-site.domain/somePage.php?list=modules',
),

MyModule/Helper/ExternalUrlHelper.php:

<?php
namespace MyModule\Helper;

use Zend\Stdlib\DispatchableInterface as Dispatchable;
use Zend\View\Helper\AbstractHelper;
use Zend\ServiceManager\ServiceLocatorAwareInterface;
use Zend\ServiceManager\ServiceLocatorInterface;
use Zend\Mvc\Controller\Plugin\PluginInterface;
use InvalidArgumentException;

class ExternalUrlHelper extends AbstractHelper implements
    ServiceLocatorAwareInterface, PluginInterface
{
    /** @var \Zend\View\HelperPluginManager  */
    protected $sm;

    /** @var Dispatchable */
    protected $controller;

    /**
     * Set service locator
     * @param ServiceLocatorInterface $serviceLocator
     */
    public function setServiceLocator(ServiceLocatorInterface $serviceLocator)
    {
        $this->sm=$serviceLocator;
    }

    /**
     * Get service locator
     * @return ServiceLocatorInterface
     */
    public function getServiceLocator()
    {
        return $this->sm;
    }

    /**
     * Set the current controller instance
     *
     * @param  Dispatchable $controller
     * @return void
     */
    public function setController(Dispatchable $controller)
    {
        $this->controller=$controller;
    }

    /**
     * Get the current controller instance
     *
     * @return null|Dispatchable
     */
    public function getController()
    {
        return $this->controller;
    }

    /**
     * @param string $name
     * @return string
     */
    public function __invoke($name)
    {
        return $this->getRouteByName($name);
    }

    /**
     * @param string $name
     * @return string
     * @throws \InvalidArgumentException
     */
    protected function getRouteByName($name)
    {
        $config=$this->sm->getServiceLocator()->get('config');
        $routes=$config['external_urls'];

        if (! isset($routes[$name])) {
            throw new InvalidArgumentException(
                sprintf('Route name %s not found', htmlspecialchars($name, ENT_QUOTES))
            );
        }

        return $routes[$name];
    }
}

in a view:

<a href="<?php echo $this->externalUrl('home'); ?>">Main portal</a>

in a controller:

$this->redirect()->toUrl($this->externalUrl('home'));