angular-cn/public/docs/_examples/architecture/ts/app/hero.service.ts

import { Injectable } from '@angular/core';

import { Hero } from './hero';
import { BackendService } from './backend.service';
import { Logger } from './logger.service';

@Injectable()
// #docregion class
export class HeroService {
  private heroes: Hero[] = [];

  constructor(
    private backend: BackendService,
    private logger: Logger) { }

  getHeroes() {
    this.backend.getAll(Hero).then( (heroes: Hero[]) => {
      this.logger.log(`Fetched ${heroes.length} heroes.`);
      this.heroes.push(...heroes); // fill cache
    });
    return this.heroes;
  }
}