Angular TypeError:在执行传递的函数时无法设置属性

我不熟悉函数式编程。在将函数传递给类型脚本中的另一个函数时，我遇到了一个错误。这是我的密码：-

export class NavigationComponent implements OnInit {

  constructor(public globals: Globals, public auth: AuthService, public placeService: PlaceService) {
    auth.handleAuthentication();
    if (auth.isAuthenticated) {
      console.log(' userName ' + this.firstName + ' userName ' + this.userName + ' dp ' + this.dpUrl);
      this.fetchProfile();
      console.log(' userName ' + this.firstName + ' userName ' + this.userName + ' dp ' + this.dpUrl);
    }
  }

  ngOnInit() {
    this.getCountries();
  }

  private firstName: any;
  private userName: any;
  private dpUrl: any;

  private fetchProfile() {
    this.auth.getProfileReponse(this.processResponse);
  }

  public processResponse(userResponse: Observable<HttpResponse<UserResp>>) {
    userResponse.subscribe(resp => {
      const user: User = { ...resp.body }.flatUser;
      console.log('user');
      console.log(user); // printing user perfetcly
      console.log(user.firstName); // printing user perfetcly
      this.firstName = user.firstName; // facing error here
      this.userName = user.userName;
      this.dpUrl = user.dpURL;
      // console.log(this.flatUser);
    });
  }
}

---

为什么这个未定义的“名字”，我使用的是angular 6测试版。请帮我解决这个问题。

这实际上是未定义的

的上下文。请尝试以下方法：

this.auth.getProfileReponse(() => this.processResponse);

箭头语法将与此绑定，它应该可以防止错误
它起作用了，爸爸，你真漂亮。非常感谢。可能是副本
this.auth.getProfileReponse(() => this.processResponse);