16장까지 예제 추가

src/chapters/chapter12.ts

@@ -36,8 +36,8 @@ export class Money implements Expression {
     return `${this.amount} ${this._currency}`;
   }
 
-  public plus(added: Money): Expression {
-    return new Money(this.amount + added.amount, this._currency);
+  public plus(addend: Money): Expression {
+    return new Money(this.amount + addend.amount, this._currency);
   }
 }
 

src/chapters/chapter13.test.ts

@@ -0,0 +1,111 @@
+import { Bank, Money } from "./chapter13";
+import type { Expression } from "./chapter13";
+import { Sum } from "./chapter13";
+
+/*
+// attempt 1
+describe("chapter 13", () => {
+  test("multiplication", () => {
+    const five: Money = Money.dollar(5);
+    expect(Money.dollar(10)).toEqual(five.times(2));
+    expect(Money.dollar(15)).toEqual(five.times(3));
+  });
+
+  test("francMultiplication", () => {
+    const five = Money.franc(5);
+    expect(Money.franc(10)).toEqual(five.times(2));
+    expect(Money.franc(15)).toEqual(five.times(3));
+  });
+
+  test("equality", () => {
+    expect(Money.dollar(5).equals(Money.dollar(5))).toBe(true);
+    expect(Money.dollar(5).equals(Money.dollar(6))).toBe(false);
+    expect(Money.franc(5).equals(Money.dollar(5))).toBe(false);
+  });
+
+  test("currency", () => {
+    expect(Money.dollar(1).currency()).toBe("USD");
+    expect(Money.franc(1).currency()).toBe("CHF");
+  });
+
+  test("simpleAddition", () => {
+    const five = Money.dollar(5);
+    const sum: Expression = five.plus(five);
+    const bank = new Bank();
+    const reduced = bank.reduce(sum, "USD");
+    expect(Money.dollar(10)).toEqual(reduced);
+  });
+
+  test("plusReturnsSum", () => {
+    const five = Money.dollar(5);
+    const result = five.plus(five);
+    const sum: Sum = result;
+
+    expect(five).toEqual(sum.augend);
+    expect(five).toEqual(sum.addend);
+  });
+
+  test("reduceSum", () => {
+    const sum = new Sum(Money.dollar(3), Money.dollar(4));
+    const bank = new Bank();
+    const result = bank.reduce(sum, "USD");
+    expect(Money.dollar(7)).toEqual(result);
+  });
+});
+*/
+
+// attempt 2
+describe("chapter 13", () => {
+  test("multiplication", () => {
+    const five: Money = Money.dollar(5);
+    expect(Money.dollar(10)).toEqual(five.times(2));
+    expect(Money.dollar(15)).toEqual(five.times(3));
+  });
+
+  test("francMultiplication", () => {
+    const five = Money.franc(5);
+    expect(Money.franc(10)).toEqual(five.times(2));
+    expect(Money.franc(15)).toEqual(five.times(3));
+  });
+
+  test("equality", () => {
+    expect(Money.dollar(5).equals(Money.dollar(5))).toBe(true);
+    expect(Money.dollar(5).equals(Money.dollar(6))).toBe(false);
+    expect(Money.franc(5).equals(Money.dollar(5))).toBe(false);
+  });
+
+  test("currency", () => {
+    expect(Money.dollar(1).currency()).toBe("USD");
+    expect(Money.franc(1).currency()).toBe("CHF");
+  });
+
+  test("simpleAddition", () => {
+    const five = Money.dollar(5);
+    const sum: Expression = five.plus(five);
+    const bank = new Bank();
+    const reduced = bank.reduce(sum, "USD");
+    expect(Money.dollar(10)).toEqual(reduced);
+  });
+
+  test("plusReturnsSum", () => {
+    const five = Money.dollar(5);
+    const result = five.plus(five);
+    const sum: Sum = result;
+
+    expect(five).toEqual(sum.augend);
+    expect(five).toEqual(sum.addend);
+  });
+
+  test("reduceSum", () => {
+    const sum = new Sum(Money.dollar(3), Money.dollar(4));
+    const bank = new Bank();
+    const result = bank.reduce(sum, "USD");
+    expect(Money.dollar(7)).toEqual(result);
+  });
+
+  test("reduceMoney", () => {
+    const bank = new Bank();
+    const result = bank.reduce(Money.dollar(1), "USD");
+    expect(Money.dollar(1)).toEqual(result);
+  });
+});

src/chapters/chapter13.ts

@@ -0,0 +1,216 @@
+/*
+// attempt 1
+export class Money implements Expression {
+  protected _amount: number;
+  protected _currency: string;
+
+  constructor(amount: number, currency: string) {
+    this._amount = amount;
+    this._currency = currency;
+  }
+
+  public get amount(): number {
+    return this._amount;
+  };
+
+  public static dollar(amount: number): Money {
+    return new Money(amount, "USD");
+  }
+
+  public static franc(amount: number): Money {
+    return new Money(amount, "CHF");
+  }
+
+  public equals(object: Object) {
+    const money = object as Money;
+    return this._amount === money._amount && this._currency === money.currency();
+  }
+
+  public times(multiplier: number): Money {
+    return new Money(this._amount * multiplier, this._currency);
+  }
+
+  public currency(): string {
+    return this._currency;
+  }
+
+  public toString() {
+    return `${this._amount} ${this._currency}`;
+  }
+
+  public plus(addend: Money): Sum {
+    return new Sum(this, addend);
+  }
+}
+
+export interface Expression {}
+
+export class Bank {
+  public reduce(source: Expression, to: string): Money {
+    const sum = source as Sum;
+    return sum.reduce(to);
+  }
+}
+
+export class Sum implements Expression {
+  public augend: Money;
+  public addend: Money;
+
+  constructor(augend: Money, addend: Money) {
+    this.augend = augend;
+    this.addend = addend;
+  }
+
+  public reduce(to: string) {
+    const amount = this.augend.amount + this.addend.amount;
+    return new Money(amount, to);
+  }
+}
+*/
+
+/*
+// attempt 2
+export class Money implements Expression {
+  protected _amount: number;
+  protected _currency: string;
+
+  constructor(amount: number, currency: string) {
+    this._amount = amount;
+    this._currency = currency;
+  }
+
+  public get amount(): number {
+    return this._amount;
+  };
+
+  public static dollar(amount: number): Money {
+    return new Money(amount, "USD");
+  }
+
+  public static franc(amount: number): Money {
+    return new Money(amount, "CHF");
+  }
+
+  public equals(object: Object) {
+    const money = object as Money;
+    return this._amount === money._amount && this._currency === money.currency();
+  }
+
+  public times(multiplier: number): Money {
+    return new Money(this._amount * multiplier, this._currency);
+  }
+
+  public currency(): string {
+    return this._currency;
+  }
+
+  public toString() {
+    return `${this._amount} ${this._currency}`;
+  }
+
+  public plus(addend: Money): Sum {
+    return new Sum(this, addend);
+  }
+}
+
+export interface Expression {}
+
+export class Bank {
+  public reduce(source: Expression, to: string): Money {
+    if (source instanceof Money) {
+      return source;
+    }
+
+    const sum = source as Sum;
+    return sum.reduce(to);
+  }
+}
+
+export class Sum implements Expression {
+  public augend: Money;
+  public addend: Money;
+
+  constructor(augend: Money, addend: Money) {
+    this.augend = augend;
+    this.addend = addend;
+  }
+
+  public reduce(to: string) {
+    const amount = this.augend.amount + this.addend.amount;
+    return new Money(amount, to);
+  }
+}
+*/
+
+// attempt 3
+export class Money implements Expression {
+  protected _amount: number;
+  protected _currency: string;
+
+  constructor(amount: number, currency: string) {
+    this._amount = amount;
+    this._currency = currency;
+  }
+
+  public get amount(): number {
+    return this._amount;
+  };
+
+  public static dollar(amount: number): Money {
+    return new Money(amount, "USD");
+  }
+
+  public static franc(amount: number): Money {
+    return new Money(amount, "CHF");
+  }
+
+  public equals(object: Object) {
+    const money = object as Money;
+    return this._amount === money._amount && this._currency === money.currency();
+  }
+
+  public times(multiplier: number): Money {
+    return new Money(this._amount * multiplier, this._currency);
+  }
+
+  public currency(): string {
+    return this._currency;
+  }
+
+  public toString() {
+    return `${this._amount} ${this._currency}`;
+  }
+
+  public plus(addend: Money): Sum {
+    return new Sum(this, addend);
+  }
+
+  public reduce(to: string) {
+    return this;
+  }
+}
+
+export interface Expression {
+  reduce(to: string): Money;
+}
+
+export class Bank {
+  public reduce(source: Expression, to: string): Money {
+    return source.reduce(to);
+  }
+}
+
+export class Sum implements Expression {
+  public augend: Money;
+  public addend: Money;
+
+  constructor(augend: Money, addend: Money) {
+    this.augend = augend;
+    this.addend = addend;
+  }
+
+  public reduce(to: string) {
+    const amount = this.augend.amount + this.addend.amount;
+    return new Money(amount, to);
+  }
+}