Using Drupal's Core classes as services

Question

I have rather a general question that would help me to undestand using services in Drupal 8+ and when it is worth to do so.

I have found a useful method createFromRoute which is part of

namespace Drupal\Core;

It is defined in Link.php file.

I have found plethora of examples in code when it is just called like this

Link::createFromRoute(... parameters here)

But, is calling this method like that a good practice? Should't this be somehow used as a service?

Why yes/no?

Answer 1

The \Drupal\Core\Link class is not used to implement a service and its createFromRoute() method is static. The only way to call it is like CommentBreadcrumbBuilder::build() does, for example.

$breadcrumb->addLink(Link::createFromRoute($this->t('Home'), '<front>'));

You could also directly create an instance of the Link class, as that same method does.

$breadcrumb->addLink(new Link($entity->label(), $entity->toUrl()));

Link::__construct() requires the text to show in the link and the URL, differently from Link::createFromRoute() which requires the text to show in the link and the route name.
(This means that, when you are creating the link from a route, Link::createFromRoute() is the method you want to use.)