greeting.service.ts

import { Inject, Injectable } from '@angular/core';
import { GreetingServiceConfig } from './greeting-service.config';

import { GREETING_SERVICE_CONFIG_INJECTION_TOKEN } from './greeting-service.token';

@Injectable()
export class GreetingService {
  constructor(
    @Inject(GREETING_SERVICE_CONFIG_INJECTION_TOKEN)
    private config: GreetingServiceConfig
  ) {}

  public initialize() {
    this.salutation = `${this.config.greeting} ${this.config.subject}!`;
  }

  public greeting(message: string): string {
    return `${this.config.greeting} ${message}!`;
  }
  public salutation: string;
}