Created
October 20, 2021 11:35
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InjectDecorator
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import 'reflect-metadata'; | |
class Injector { | |
// Map<interfaceType, instance> | |
services: Map<Function, Object> = new Map(); | |
registerService(interfaceType: Function, instance: Object) { | |
this.services.set(interfaceType, instance); | |
} | |
getService(interfaceType: Function): Object { | |
return this.services.get(interfaceType); | |
} | |
} | |
class ConsoleLogService { | |
private seed = Math.random(); | |
public log(msg: string) { console.log([this.seed], msg); } | |
} | |
const globalInjector = new Injector(); | |
globalInjector.registerService(ConsoleLogService, new ConsoleLogService()); | |
function Inject(target: Object, propertyKey: string): any { | |
// конструктор типа свойства === ConsoleLogService | |
const propertyType: Function = Reflect.getMetadata("design:type", target, propertyKey); | |
const descriptor = { | |
get: function () { | |
// можно определять свой инжектор в класс декорируемого свойства, | |
// чтобы брать сервисы из него (как providers в @Component в Ангуляре) | |
// либо берем сервисы из корневого инжектора | |
const injector = this.injector || globalInjector; | |
return injector.getService(propertyType); | |
} | |
}; | |
Object.defineProperty(target, propertyKey, descriptor); | |
return descriptor; | |
} | |
class Component { | |
public injector; | |
@Inject | |
private logService: ConsoleLogService; | |
sayHello() { | |
this.logService.log('Hello world'); | |
} | |
} | |
const component1 = new Component(); | |
component1.sayHello(); | |
const component2 = new Component(); | |
const localInjector = new Injector(); | |
localInjector.registerService(ConsoleLogService, new ConsoleLogService()); | |
component2.injector = localInjector; | |
component2.sayHello(); | |
component1.sayHello(); | |
component2.sayHello(); |
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