diff --git a/components/dependency_injection/configurators.rst b/components/dependency_injection/configurators.rst new file mode 100644 index 00000000000..23708c67419 --- /dev/null +++ b/components/dependency_injection/configurators.rst @@ -0,0 +1,225 @@ +.. index:: + single: Dependency Injection; Service configurators + +Configuring Services with a Service Configurator +================================================ + +The Service Configurator is a feature of the Dependency Injection Container that +allows you to use a callable to configure a service after its instantiation. + +You can specify a method in another service, a PHP function or a static method +in a class. The service instance is passed to the callable, allowing the +configurator to do whatever it needs to configure the service after its +creation. + +A Service Configurator can be used, for example, when you a have a service that +requires complex setup based on configuration settings coming from different +sources/services. Using an external configurator, you can maintain the service +implementation clean and decoupled from the other objects that provide the +configuration for the service. + +Another interesting use case is when you have multiple objects that share a +common configuration or that should be configured in a similar way at runtime. + +For example, suppose you have an application where you send different types of +emails to users. Emails are passed through different formatters that could be +enabled or not depending on some dynamic application settings. You start +defining a ``NewsletterManager`` class like this:: + + class NewsletterManager implements EmailFormatterAwareInterface + { + protected $mailer; + protected $enabledFormatters; + + public function setMailer(Mailer $mailer) + { + $this->mailer = $mailer; + } + + public function setEnabledFormatters(array $enabledFormatters) + { + $this->enabledFormatters = $enabledFormatters; + } + + // ... + } + + +and also a ``GreetingCardManager`` class:: + + class GreetingCardManager implements EmailFormatterAwareInterface + { + protected $mailer; + protected $enabledFormatters; + + public function setMailer(Mailer $mailer) + { + $this->mailer = $mailer; + } + + public function setEnabledFormatters(array $enabledFormatters) + { + $this->enabledFormatters = $enabledFormatters; + } + + // ... + } + + +As commented before, the formatters should be set at runtime depending on +application settings, so we also have a ``EmailFormatterManager`` class which is +responsible for loading and validating formatters enabled in the application:: + + class EmailFormatterManager + { + protected $enabledFormatters; + + public function loadFormatters() + { + // ... + } + + public function getEnabledFormatters() + { + return $this->enabledFormatters; + } + + // ... + } + +If your goal is to avoid having to couple ``NewsletterManager`` and +``GreetingCardManager`` with ``EmailFormatterManager``, then you might want to +create a configurator class to configure these instances:: + + class EmailConfigurator + { + private $formatterManager; + + public function __construct(EmailFormatterManager $formatterManager) + { + $this->formatterManager = $formatterManager; + } + + public function configure(EmailFormatterAwareInterface $emailManager) + { + $emailManager->setEnabledFormatters( + $this->formatterManager->getEnabledFormatters() + ); + } + + // ... + } + +``EmailConfigurator`` task is to inject enabled filters to ``NewsletterManager`` +and ``GreetingCardManager`` because they are not aware of where the enabled +filters come from. In the other hand, the ``EmailFormatterManager`` holds the +knowledge about the enabled formatters and how to load them, keeping the single +responsibility principle. + +Configurator Service Config +--------------------------- + +The service config for the above classes would look something like this: + +.. configuration-block:: + + .. code-block:: yaml + + parameters: + # ... + newsletter_manager.class: NewsletterManager + greeting_card_manager.class: GreetingCardManager + email_formatter_manager.class: EmailFormatterManager + email_configurator.class: EmailConfigurator + + services: + my_mailer: + # ... + + email_formatter_manager: + class: "%email_formatter_manager.class%" + # ... + + email_configurator: + class: "%email_configurator.class%" + arguments: [@email_formatter_manager] + # ... + + newsletter_manager: + class: "%newsletter_manager.class%" + calls: + - [setMailer, [@my_mailer]] + configurator: [@email_configurator, configure] + + greeting_card_manager: + class: "%greeting_card_manager.class%" + calls: + - [setMailer, [@my_mailer]] + configurator: [@email_configurator, configure] + + + .. code-block:: xml + + + + NewsletterManager + GreetingCardManager + EmailFormatterManager + EmailConfigurator + + + + + + + + + + + + + + + + + + + + + + + + + + + + .. code-block:: php + + use Symfony\Component\DependencyInjection\Definition; + use Symfony\Component\DependencyInjection\Reference; + + // ... + $container->setParameter('newsletter_manager.class', 'NewsletterManager'); + $container->setParameter('greeting_card_manager.class', 'GreetingCardManager'); + $container->setParameter('email_formatter_manager.class', 'EmailFormatterManager'); + $container->setParameter('email_configurator.class', 'EmailConfigurator'); + + $container->setDefinition('my_mailer', ...); + $container->setDefinition('email_formatter_manager', ...); + $container->setDefinition('email_configurator', ...); + $container->setDefinition('newsletter_manager', new Definition( + '%newsletter_manager.class%' + ))->addMethodCall('setMailer', array( + new Reference('my_mailer'), + ))->setConfigurator(array( + new Reference('email_configurator'), + 'configure', + ))); + $container->setDefinition('greeting_card_manager', new Definition( + '%greeting_card_manager.class%' + ))->addMethodCall('setMailer', array( + new Reference('my_mailer'), + ))->setConfigurator(array( + new Reference('email_configurator'), + 'configure', + ))); diff --git a/components/dependency_injection/index.rst b/components/dependency_injection/index.rst index 8a3a856856d..2b60d8576d3 100644 --- a/components/dependency_injection/index.rst +++ b/components/dependency_injection/index.rst @@ -10,6 +10,7 @@ compilation tags factories + configurators parentservices advanced workflow diff --git a/components/map.rst.inc b/components/map.rst.inc index 8f9e1464da5..db0d47278f0 100644 --- a/components/map.rst.inc +++ b/components/map.rst.inc @@ -30,6 +30,7 @@ * :doc:`/components/dependency_injection/compilation` * :doc:`/components/dependency_injection/tags` * :doc:`/components/dependency_injection/factories` + * :doc:`/components/dependency_injection/configurators` * :doc:`/components/dependency_injection/parentservices` * :doc:`/components/dependency_injection/advanced` * :doc:`/components/dependency_injection/workflow`