[DI] Document param() and abstract_arg()

Author: javiereguiluz

components/dependency_injection.rst

@@ -299,7 +299,8 @@ config files:
             $services = $configurator->services();
 
             $services->set('mailer', 'Mailer')
-                ->args(['%mailer.transport%'])
+                // the param() method was introduced in Symfony 5.2.
+                ->args([param('mailer.transport')])
             ;
 
             $services->set('newsletter_manager', 'NewsletterManager')

service_container.rst

@@ -1116,7 +1116,7 @@ admin email. In this case, each needs to have a unique service id:
                 ->args([
                    service(MessageGenerator::class),
                    service('mailer'),
-                    '[email protected]',
+                   '[email protected]',
                 ]);
 
             $services->set('site_update_manager.normal_users', SiteUpdateManager::class)

service_container/tags.rst

@@ -273,7 +273,8 @@ For example, you may add the following transports as services:
             $services = $configurator->services();
 
             $services->set(\Swift_SmtpTransport::class)
-                ->args(['%mailer_host%'])
+                // the param() method was introduced in Symfony 5.2.
+                ->args([param('mailer_host')])
                 ->tag('app.mail_transport')
             ;
 
@@ -437,7 +438,8 @@ To answer this, change the service declaration:
             $services = $configurator->services();
 
             $services->set(\Swift_SmtpTransport::class)
-                ->args(['%mailer_host%'])
+                // the param() method was introduced in Symfony 5.2.
+                ->args([param('mailer_host')])
                 ->tag('app.mail_transport', ['alias' => 'smtp'])
             ;