Yii source code interpretation-Service Locator (Service Locator)

SL is also designed to be decoupled and is very suitable for service- and component-based applications.

Service Locator acts as a runtime linker and can dynamically modify the services selected by a class at runtime without having to make any modifications to the class.

A class can be targeted to increase, decrease, or replace the services it needs at runtime, thereby achieving a certain degree of optimization.

Achieve complete decoupling of service providers and service users, facilitating independent testing and code reuse across frameworks.

Basic functions

SL in Yii is implemented by yiidiServiceLocator

<code>class ServiceLocator extends Component{
    // 用于缓存服务、组件等的实例
    private $_components = [];
    
    // 保存服务和组件的定义，通常为配置数组，可以用来创建具体的实例
    private $_definitions = [];
    
    // 重载了getter, 使得访问服务和组件与访问类的属性一样。
    // 保留了原来Component的getter所具有的功能
    public function __get($name){}
}</code>

Data structure

SL provides methods to register services and components.

$_components is used to cache instances of components or services in SL and is a readable and writable attribute.

Reference

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