12.8 슈퍼클래스 추출하기.md

• 12.8 슈퍼클래스 추출하기

  1. before

     class Employee {
       #name;
       #id;
       #monthlyCost;
       constructor(name, id, monthlyCost) {
         this.#name = name;
         this.#id = id;
         this.#monthlyCost = monthlyCost;
       }
       get monthlyCost() {
         return this.#monthlyCost;
       }
       get name() {
         return this.#name;
       }
       get id() {
         return this.#id;
       }
       get annualCost() {
         return this.#monthlyCost * 12;
       }
     }
     
     class Department {
       #name;
       #staff;
       constructor(name, staff) {
         this.#name = name;
         this.#staff = staff;
       }
       get name() {
         return this.#name;
       }
       get staff() {
         return this.#staff;
       }
       get totalMonthlyCost() {
         return this.#staff
           .map((e) => e.monthlyCost)
           .reduce((sum, cost) => sum + cost, 0);
       }
       get headCount() {
         return this.staff.length;
       }
       get totalAnnualCost() {
         return this.totalMonthlyCost * 12;
       }
     }

  2. after

  class Party {
    _name;
    constructor(name) {
      this._name = name;
    }
    get name() {
      return this._name;
    }
    get annualCost() {
      return this.monthlyCost * 12;
    }
  }
  
  class Employee extends Party {
    #id;
    #monthlyCost;
    constructor(name, id, monthlyCost) {
      super(name);
      this.#id = id;
      this.#monthlyCost = monthlyCost;
    }
    get monthlyCost() {
      return this.#monthlyCost;
    }
    get id() {
      return this.#id;
    }
  }
  
  class Department extends Party {
    #staff;
    constructor(name, staff) {
      super(name);
      this.#staff = staff;
    }
    get staff() {
      return this.#staff;
    }
    get monthlyCost() {
      return this.#staff
        .map((e) => e.monthlyCost)
        .reduce((sum, cost) => sum + cost, 0);
    }
    get headCount() {
      return this.staff.length;
    }
  }