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Edited; very clean!

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Larry Ullman
2014-07-13 16:24:49 -04:00
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docs/guide/concept-service-locator.md
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@ -2,19 +2,19 @@ Service Locator
=============== ===============
A service locator is an object that knows how to provide all sorts of services (or components) that an application A service locator is an object that knows how to provide all sorts of services (or components) that an application
might need. Within a service locator, each component has only a single instance which is uniquely identified by an ID. might need. Within a service locator, each component exists as only a single instance, uniquely identified by an ID.
You use the ID to retrieve a component from the service locator. You use the ID to retrieve a component from the service locator.
In Yii, a service locator is simply an instance of [[yii\di\ServiceLocator]] or its child class. In Yii, a service locator is simply an instance of [[yii\di\ServiceLocator]], or from a child class.
The most commonly used service locator in Yii is the *application* object which can be accessed through The most commonly used service locator in Yii is the *application* object, which can be accessed through
`\Yii::$app`. The services it provides are called *application components*, such as the `request`, `response`, `\Yii::$app`. The services it provides are called *application components*, such as the `request`, `response`, and
`urlManager` components. You may configure these components or even replace them with your own implementations easily `urlManager` components. You may configure these components, or even replace them with your own implementations, easily
through functionality provided by the service locator. through functionality provided by the service locator.
Besides the application object, each module object is also a service locator. Besides the application object, each module object is also a service locator.
To use a service locator, the first step is to register components. A component can be registered To use a service locator, the first step is to register components with it. A component can be registered
via [[yii\di\ServiceLocator::set()]]. The following code shows different ways of registering components: via [[yii\di\ServiceLocator::set()]]. The following code shows different ways of registering components:
```php ```php
@ -43,7 +43,7 @@ $locator->set('search', function () {
$locator->set('pageCache', new FileCache); $locator->set('pageCache', new FileCache);
``` ```
Once a component is registered, you can access it using its ID in one of the following two ways: Once a component has been registered, you can access it using its ID, in one of the two following ways:
```php ```php
$cache = $locator->get('cache'); $cache = $locator->get('cache');
@ -53,7 +53,7 @@ $cache = $locator->cache;
As shown above, [[yii\di\ServiceLocator]] allows you to access a component like a property using the component ID. As shown above, [[yii\di\ServiceLocator]] allows you to access a component like a property using the component ID.
When you access a component for the first time, [[yii\di\ServiceLocator]] will use the component registration When you access a component for the first time, [[yii\di\ServiceLocator]] will use the component registration
information to create a new instance of the component and return it. Later if the component is accessed again, information to create a new instance of the component and return it. Later, if the component is accessed again,
the service locator will return the same instance. the service locator will return the same instance.
You may use [[yii\di\ServiceLocator::has()]] to check if a component ID has already been registered. You may use [[yii\di\ServiceLocator::has()]] to check if a component ID has already been registered.
@ -61,9 +61,8 @@ If you call [[yii\di\ServiceLocator::get()]] with an invalid ID, an exception wi
Because service locators are often being created with [configurations](concept-configurations.md), Because service locators are often being created with [configurations](concept-configurations.md),
a writable property named [[yii\di\ServiceLocator::setComponents()|components]] is provided so that a writable property named [[yii\di\ServiceLocator::setComponents()|components]] is provided. This allows you to configure and register multiple components at once. The following code shows a configuration array
you can configure it and register multiple components at once. The following code shows a configuration array that can be used to configure an application, while also registering the "db", "cache" and "search" components:
that can be used to configure an application and register the "db", "cache" and "search" components:
```php ```php
return [ return [