[리팩터링 2판 스터디] 3장. 코드에서 나는 악취

// 변경 전
function example(start, end) {
	const range = end - start;
	console.log(range);
}

// 변경 후 ///////////////////////////
function example(range) {
	console.log(getRange(range));
}

function getRange(range) {
	return range.end - range.start;
}

// 변경 전
function score(candidate, medicalExam, scoringGuide) {
	let result = 0;
	let healthLevel = 0;
	...
}

// 변경후 ///////////////////////////
class Scorer {
	constructor(candidate, medicalExam, scoringGuide) {
		this._candidate = candidate;
		this._medicalExam = medicalExam;
		this._scoringGuide = scoringGuide;
	}

	execute() {
		this._result = 0;
		this._healthLevel = 0;
		...
	}
}

// 변경 전
if (!date.isBefore(plan.summerStart) && !date.isAfter(plan.summerEnd)) {
	charge = quantity * plan.summerRate;
} else {
	charge = quantity * plan.regularRate;
}

// 변경 후 ///////////////////////////
if (summer())
	charge = summerCharge();
else
	charge = regularCharge();

function summer() {
	return !date.isBefore(plan.summerStart) && !date.isAfter(plan.summerEnd);
}

function charge(key) {
	return quantity * plan[key]
}

function summerCharge() {
	return quantity * plan.summerRate;
}

function regularCharge() {
	return quantity * plan.regularRate;
}

// 변경 전
function plumage(bird) {
	switch (bird.type) {
		case 'EuropeanSwallow':
				return 'average';
		case 'AfricanSwallow':
				return (bird.numberOfCoconuts > 2) ? 'tired' : 'average';
		case 'NorwegianBlueParrot':
				return (bird.voltage > 100) ? 'scorched' : 'beautiful';
		default:
				return 'unknown';
	}
}

function airSpeedVelocity(bird) {
	switch (bird.type) {
		case 'EuropeanSwallow':
				return 35;
		case 'AfricanSwallow':
				return 40 - 2 * bird.numberOfCoconuts;
		case 'NorwegianBlueParrot':
				return (bird.isNailed) ? 0 : 10 + bird.voltage / 10;
		default:
				return null;
	}
}


// 변경 후 ///////////////////////////
class Bird {
	constructor(birdObject) {
		Object.assign(this, birdObject);
	}

	get plumage() {
		return 'unknown';
	}

	get airSpeedVelocity() {
		return null;
	}
}

class EuropeanSwallow extends Bird {
	get plumage() {
		return 'average';
	}

	get airSpeedVelocity() {
		return 35;
	}
}

class AfricanSwallow extends Bird {
	get plumage() {
		return (this.numberOfCoconuts > 2) ? 'tired' : 'average';
	}

	get airSpeedVelocity() {
		return 40 - 2 * this.numberOfCoconuts;
	}
}

class NorwegianBlueParrot extends Bird {
	get plumage() {
		return (this.voltage > 100) ? 'scorched' : 'beautiful';
	}

	get airSpeedVelocity() {
		return (this.isNailed) ? 0 : 10 + this.voltage / 10;
	}
}

function createBird(bird) {
	switch (bird.type) {
		case 'EuropeanSwallow':
			return new EuropeanSwallow(bird);
		case 'AfricanSwallow':
			return new AfricanSwallow(bird);
		case 'NorwegianBlueParrot':
			return new NorwegianBlueParrot(bird);
		default:
			return new Bird(bird);
	}
}

// 변경 전
let totalSalary = 0;
let averageAge = 0;
for (const p of people) {
	averageAge += p.age;
	totalSalary += p.salary;
}

averageAge = averageAge / people.length;

// 변경 후 ///////////////////////////
let totalSalary = 0;
for (const p of people) {
	totalSalary += p.salary;
}

let averageAge = 0;
for (const p of people) {
	averageAge += p.age;
}

averageAge = averageAge / people.length;

// 변경 전
availableVacation(anEmployee, anEmployee.grade);
function availableVacation(anEmployee, grade) {...}

// 변경 후 ///////////////////////////
availableVacation(anEmployee);
function availableVacation(anEmployee) {
	const grade = anEmployee.grade;
	...
}

// 변경 전
function setDimension(name, value) {
	if (name === 'height') {
		this.height = value;
		return;
	}
	if (name === 'width') {
		this.width = value;
		return;
	}
}

// 변경 후 ///////////////////////////
function setHeight(value) { this.height = value; }
function setWidth(value) { this.width = value; }

// 변경 전
function base(aReading) {...}
function taxableCharge(aReading) {...}
function calculateBaseCharge(aReading) {...}

// 변경 후 ///////////////////////////
class Reading {
	base() {...}
	taxableCharge() {...}
	calculateBaseCharge() {...}
}

// 변경 전
let defaultOwner = {firstName: 'Cheese', lastName: 'Ball'};
defaultOwner = {firstName: 'Mozza', lastName: 'Cheese'};
spaceShip.owner = defaultOwner;

// 변경 후 ///////////////////////////
let defaultOwnerData = {firstName: 'Cheese', lastName: 'Ball'};
export function getDefaultOwner() {
	return defaultOwnerData;
}

export function setDefaultOwner(arg) {
	defaultOwnerData = arg;
}

setDefaultOwner({firstName: 'Mozza', lastName: 'Cheese'});
spaceShip.owner = getDefaultOwner();

// 변경 전
let temp = 2 * (width + height);
console.log(temp);
temp = width * height;
console.log(temp);

// 변경 후 ///////////////////////////
const perimeter = 2 * (width + height);
console.log(perimeter);
const area = height * width;
console.log(area);

// 변경 전
function getTotalOunstandingAndSendBill() {
	const result = customer.invoices.reduce((total, each) => each.amount + total, 0);
	sendBill();
	return result;
}

// 변경 후 ///////////////////////////
function totalOutstanding() {
	return customer.invoices.reduce((total, each) => each.amount + total, 0);
}

function sendBill() {
	...
}

// 변경 전
get discountTotal() {
	return this._discountTotal;
}

set discount(aNumber) {
	const old = this._discount;
	this._discount = aNumber;
	this._discountedTotal += old - aNumber;
}

// 변경 후 ///////////////////////////
get discountTotal() {
	return this._baseTotal - this._discount;
}

set discount(aNumber) {
	this._discount = aNumber;
}

// 변경 전
funciton base(aReading) {...}

funciton taxableCharge(aReading) {...}

// 변경 후 ///////////////////////////
funciton enrichReading(argReading) {
	const aReading = _.cloneDeep(argReading);
	aReading.baseCharge = base(aReading);
	aReading.taxableCharge = taxableCharge(aReading);
	return aReading;
}

// 변경 전
class Product {
	applyDiscount(arg) {
		this._price.amount -= arg;
	}
}

// 변경 후 ///////////////////////////
class Product {
	applyDiscount(arg) {
		this._price = new Money(this._price.amount - arg);
	}
}

// 변경 전
const orderData = orderString.split(',');
const productPrice = priceList[orderData[0].split('-')[1]];
const orderPrice = parseInt(orderData[1]) * productPrice;

// 변경 후 ///////////////////////////
const orderRecord = parseOrder(order);
const orderPrice = price(orderRecord, priceList);
function parseOrder(aString) {
	const values = aString.split(',');
	return ({
		productID: values[0].split('-')[1],
		quantity: parseInt(values[1]),
	});
}

function price(order, priceList) {
	return order.quantity * priceList[order.productID];
}

// 변경 전
class Person {
	get officeAreaCode() {return this._officeAreaCode;}
	get officeNumber() {return this._officeNumber;}
}

// 변경 후 ///////////////////////////
class Person {
	constructor() {
		this._telephoneNumber = new TelephoneNumber();
	}
	
	get officeAreaCode() {return this._telephoneNumber.areaCode;}
	get officeAreaCode() {return this._telephoneNumber.number;}
}
	
class TelephoneNumber {
	get areaCode() {return this._areaCode;}
	get number() {return this._number;}
}

// 변경 전
function getRating(dirver) {
	return moreThanFiveLateDeliveries(driver) ? 2 : 1;
}

function moreThanFiveLateDeliveries(driver) {
	return driver.numberOfLateDeliveries > 5;
}

// 변경 후 ///////////////////////////
function getRating(driver) {
	return (driver.numberOfLateDeliveries > 5) ? 2 : 1;
}

// 변경 전
class Person {
	constructor() {
		this._telephoneNumber = new TelephoneNumber();
	}
	
	get officeAreaCode() {return this._telephoneNumber.areaCode;}
	get officeAreaCode() {return this._telephoneNumber.number;}
}

class TelephoneNumber {
	get areaCode() {return this._areaCode;}
	get number() {return this._number;}
}
	
// 변경 후 ///////////////////////////
class Person {
	get officeAreaCode() {return this._officeAreaCode;}
	get officeNumber() {return this._officeNumber;}
}

 // 변경 전
class Account {
	get overdraftCharge() {...}
	...
}

class AccountType {
	...
}

// 변경 후 ///////////////////////////
class Account {
	...
}

class AccountType {
	get overdraftCharge() {...}
	...
}

// 변경 전
const myCpus = ['Intel Core i7', 'Core i5', 'AMD RyZen 9'];
const myIntelCpus = myCpus.filter((cpu) => cpu.startsWith('Intel') || cpu.startsWith('Core'));

// 변경 후 (1) ///////////////////////////
const myCpus = [
	{name: 'Intel Core i7', brand: 'Intel'},
	{name: 'Core i5', brand: 'Intel'},
	{name: 'AMD RyZen 9', brand: 'AMD'},
];

const myIntelCpus = myCpus.filter((cpu) => cpu.brand == 'Intel');

// 변경 후 (2) ///////////////////////////
const IntelBrand = {
	name: "Intel",
	sloagun: "Leap Ahead",
	ceo: "Robert Holmes Swan",
	stock: 52.82
}

const AmdBrand = {
	name: "AMD",
	sloagun: "Fusion is Future",
	ceo: "Lisa Tzwu-Fang Su",
	stock: 83.1
}

const myCpus = [
	{ name: "Intel Core i7", brand: IntelBrand },
	{ name: "Intel Core i5", brand: IntelBrand },
	{ name: "AMD RyZen 9", brand: AmdBrand }
]

const myIntelCpus = myCpus.filter(cpu => cpu.brand.stock <= 50.0);

// 변경 전
function createEmployee(name, type) {
	return new Employee(name, type);
}

// 변경 후 ///////////////////////////
function createEmployee(name, type) {
	switch (type) {
		case 'engineer': return new Engineer(name);
		case 'salesPerson': return new SalesPerson(name);
		case 'manager': return new Manager(name);
	}
}

// 변경 전
const names = [];
for (const i of input) {
	if (i.job === 'programmer') {
		names.push(i.name);
	}
}
	
// 변경 후 ///////////////////////////
const names = input
	.filter(i => i.job === 'programmer')
	.map(i => i.name);

// 변경 전
class Employee {...}
class Salesperson extends Employee {...}

// 변경 후 ///////////////////////////
class Employee {...}

// 변경 전
manager = aPerson.department.manager;
class Person {
	constructor(aDepartment) {
		this._department = aDepartment
	}
	
	get department() {
		return this._department;
	}
}
	
class Department {
	constructor(aManager) {
		this._manager = aManager;
	}
	
	get manager() {
		return this._manager;
	}
}
	
// 변경 후 ///////////////////////////
manager = aPerson.manager;
class Person {
	constructor(aDepartment) {
		this._department = aDepartment
	}
	
	get manager() {
		return this._department.manager;
	}
}
	
class Department {
	constructor(aManager) {
		this._manager = aManager;
	}
	
	get manager() {
		return this._manager;
	}
}

managerName = aPerson.department.manager.name;
managerName = aPerson.department.managerName; // 관리자 객체의 존재를 숨김
managerName = aPerson.manager.name; // 부서 객체의 존재를 숨김
managerName = aPerson.managerName; // 부서 객체와 관리자 객체 모두의 존재를 숨김

// 변경 전
class Order {
  get daysToShip() {
		return this._warehouse.daysToShip;
  }
}
	
class PriorityOrder extends Order {
  get daysToShip() {
		return this._priorityPlan.daysToShip;
  }
}
	
// 변경 후 ///////////////////////////
class Order {
	constructor() {
		this._priorityDelegate = new PriorityOrderDelegate();
	}
	
	get daysToShip() {
		return (this._priorityDelegate)
			? this._priorityDelegate.daysToShip
			: this._warehouse.daysToShip;
  }
}
	
class PriorityOrderDelegate {
  get daysToShip() {
		return this._priorityPlan.daysToShip
  }
}

// 변경 전
class List {...}
class Stack extends List {...}

// 변경 후 ///////////////////////////
class Stack {
  constructor() {
		this._storage = new List();
  }
}
class List {...}

// 변경 전
class Department {
  get totalAnnualCost() {...}
	get name() {...}
	get headCount() {...}
}
	
class Employee {
  get annualCost() {...}
	get name() {...}
	get id() {...}
}
	
// 변경 후 ///////////////////////////
class Party {
  get name() {...}
	get annualCost() {...}
}
	
class Department extends Party {
  get annualCost() {...}
	get headCount() {...}
}
	
class Employee extends Party {
  get annualCost() {...}
	get id() {...}
}

// 변경 전
organization = {name: "Acme Gooseberries", country: "GB"};

// 변경 후 ///////////////////////////
class Organization {
  constructor(data) {
		this._name = data.name;
		this._country = data.country;
  }
	
	get name(){return this._name;}
	set name(arg) {this._name = arg;}
	get country(){return this._country;}
	set country(arg) {this._country = arg;}
}

// 변경 전
class Employee {
	private String quota;
  get quota {...}
}
	
class Engineer extends Employee {...}
class Salesman extends Employee {...}
	
// 변경 후 ///////////////////////////
class Employee {...}
class Engineer extends Employee {...}
class Salesman extends Employee {
	protected String quota;
  get quota {...}  
}

// javascript
console.assert(returnFalse()) // 콘솔에 assert 에러 표시 (참이면 아무 동작 안함)

// nodeJS
const assert = require('assert');
assert(returnFalse()); // throw AssertionError!
assert.ok(returnFalse()); // assert()와 동일
assert.ifError(returnFalse()) // Pass

// 변경 전
if (this.discountRate)
  base = base - (this.discountRate * base);

// 변경 후 ///////////////////////////
assert(this.discountRate >= 0);
if (this.discountRate)
  base = base - (this.discountRate * base);