Zend\ServiceManagerΒΆ
The Service Locator design pattern is implemented by the Zend\ServiceManager
component.
The Service Locator is a service/object locator, tasked with retrieving other objects.
Following is the Zend\ServiceManager\ServiceLocatorInterface
API:
1 2 3 4 5 6 7 | namespace Zend\ServiceManager;
interface ServiceLocatorInterface
{
public function get($name);
public function has($name);
}
|
has($name)
, tests whether theServiceManager
has a named service;get($name)
, retrieves a service by the given name.
A Zend\ServiceManager\ServiceManager
is an implementation of the ServiceLocatorInterface
.
In addition to the above described methods, the ServiceManager
provides additional API:
Service registration.
ServiceManager::setService
allows you to register an object as a service:1 2 3 4 5
$serviceManager->setService('my-foo', new stdClass()); $serviceManager->setService('my-settings', array('password' => 'super-secret')); var_dump($serviceManager->get('my-foo')); // an instance of stdClass var_dump($serviceManager->get('my-settings')); // array('password' => 'super-secret')
Lazy-loaded service objects.
ServiceManager::setInvokableClass
allows you to tell theServiceManager
what class to instantiate when a particular service is requested:1 2 3
$serviceManager->setInvokableClass('foo-service-name', 'Fully\Qualified\Classname'); var_dump($serviceManager->get('foo-service-name')); // an instance of Fully\Qualified\Classname
Service factories. Instead of an actual object instance or a class name, you can tell the
ServiceManager
to invoke a provided factory in order to get the object instance. Factories may be either a PHP callback, an object implementingZend\ServiceManager\FactoryInterface
, or the name of a class implementing that interface:1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
use Zend\ServiceManager\FactoryInterface; use Zend\ServiceManager\ServiceLocatorInterface; class MyFactory implements FactoryInterface { public function createService(ServiceLocatorInterface $serviceLocator) { return new \stdClass(); } } // registering a factory instance $serviceManager->setFactory('foo-service-name', new MyFactory()); // registering a factory by factory class name $serviceManager->setFactory('bar-service-name', 'MyFactory'); // registering a callback as a factory $serviceManager->setFactory('baz-service-name', function () { return new \stdClass(); }); var_dump($serviceManager->get('foo-service-name')); // stdClass(1) var_dump($serviceManager->get('bar-service-name')); // stdClass(2) var_dump($serviceManager->get('baz-service-name')); // stdClass(3)
Service aliasing. With
ServiceManager::setAlias
you can create aliases of any registered service, factory or invokable, or even other aliases:1 2 3 4 5 6 7 8 9 10
$foo = new \stdClass(); $foo->bar = 'baz!'; $serviceManager->setService('my-foo', $foo); $serviceManager->setAlias('my-bar', 'my-foo'); $serviceManager->setAlias('my-baz', 'my-bar'); var_dump($serviceManager->get('my-foo')->bar); // baz! var_dump($serviceManager->get('my-bar')->bar); // baz! var_dump($serviceManager->get('my-baz')->bar); // baz!
Abstract factories. An abstract factory can be considered as a “fallback” factory. If the service manager was not able to find a service for the requested name, it will check the registered abstract factories:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
use Zend\ServiceManager\ServiceLocatorInterface; use Zend\ServiceManager\AbstractFactoryInterface; class MyAbstractFactory implements AbstractFactoryInterface { public function canCreateServiceWithName(ServiceLocatorInterface $serviceLocator, $name, $requestedName) { // this abstract factory only knows about 'foo' and 'bar' return $requestedName === 'foo' || $requestedName === 'bar'; } public function createServiceWithName(ServiceLocatorInterface $serviceLocator, $name, $requestedName) { $service = new \stdClass(); $service->name = $requestedName; return $service; } } $serviceManager->addAbstractFactory('MyAbstractFactory'); var_dump($serviceManager->get('foo')->name); // foo var_dump($serviceManager->get('bar')->name); // bar var_dump($serviceManager->get('baz')->name); // exception! Zend\ServiceManager\Exception\ServiceNotFoundException
Initializers. You may want certain injection points to be always called. As an example, any object you load via the service manager that implements
Zend\EventManager\EventManagerAwareInterface
should likely receive anEventManager
instance. Initializers are PHP callbacks or classes implementingZend\ServiceManager\InitializerInterface
. They receive the new instance, and can then manipulate it:1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
use Zend\ServiceManager\ServiceLocatorInterface; use Zend\ServiceManager\InitializerInterface; class MyInitializer implements InitializerInterface { public function initialize($instance, ServiceLocatorInterface $serviceLocator) { if ($instance instanceof \stdClass) { $instance->initialized = 'initialized!'; } } } $serviceManager->addInitializer('MyInitializer'); $serviceManager->setInvokableClass('my-service', 'stdClass'); var_dump($serviceManager->get('my-service')->initialized); // initialized!
In addition to the above, the ServiceManager
also provides optional ties to Zend\Di
, allowing Di
to act
as an initializer or an abstract factory for the service manager.