import { Component } from '@angular/core' ; import { MySpecialLoggerService } from './my-special-logger.service' ; import { LogLevel } from './log-level.enum' ; @ Component ( { selector : 'mpl-root' , templateUrl : './app.component.html' , styleUrls : [ './app.component.css' ] } ) export class AppComponent { title = 'mpl works!' ; constructor ( private logger ) { } printDebugLog ( ) { this . logger . debug ( "test depenency injector tree!" ) ; } }