領域知識與SOLID單一責任原則的解釋

class Employee {
  public calculatePay (): number {
    // implement algorithm for hr, accounting and it
  }
  public reportHours (): number {
    // implement algorithm for hr, accounting and it
  }

  public save (): Promise<void> {
    // implement algorithm for hr, accounting and it
  }
}

abstract class Employee {
  // This needs to be implemented
  abstract calculatePay (): number;
  // This needs to be implemented
  abstract reportHours (): number;
  // let's assume THIS is going to be the 
  // same algorithm for each employee- it can
  // be shared here.
  protected save (): Promise<void> {
    // common save algorithm
  }
}

class HR extends Employee {
  calculatePay (): number {
    // implement own algorithm
  }
  reportHours (): number {
    // implement own algorithm
  }
}

class Accounting extends Employee {
  calculatePay (): number {
    // implement own algorithm
  }
  reportHours (): number {
    // implement own algorithm
  }

}

class IT extends Employee {
  ...
}

const UserModel = require('models/user');
const EmailService = require('services/email');
const NotificationService = require('services/notification');
const Logger = require('services/logger');

const removeUserHandler = async (userId) => {
  const message = 'Your account has been deleted';
  try {
    const user = await UserModel.getUser(userId);
    await UserModel.removeUser(userId);
    await EmailService.send(userId, message);
    await NotificationService.push(userId, message);
    return true;
  } catch (e) {
    console.error(e);
    Logger.send('removeUserHandler', e);
  };
  return true;
};