重构:Move Method 笔记

重构:Move Method

           Move Method就是将方法迁移到合适的位置。

           条件：当一个方法被其他类使用比在它所在类中的使用还要频繁时，我们就需要将方法迁移到更频繁地使用它的类中(Move Method重构)

           范例如下:

  public class BankAccount
    {
        public BankAccount(int accountNum)
        {
            AccountNum = accountNum;
        }
        public int AccountNum { get; private set; }
        public double CalculateInterestRate()
        {
            if (AccountNum > 800)
                return 0.02;
            if (AccountNum > 10&&AccountNum<=800)
                return 0.03;
            return 0.05;
        }
    }

    public class AccountInterest
    {
        public BankAccount Account { get; private set; }
        public AccountInterest(BankAccount account)
        {
            Account = account;
        }
        public double InterestRate
        {
            get { return Account.CalculateInterestRate(); }

        }
        public bool IntroductoryRate
        {
            get { return Account.CalculateInterestRate() < 0.05; }
        }

    }

      发现后者比前者使用标注中的方法的频率更高，因此将该方法移动至后者中。 

      修改后代码：

    public class BankAccount
    {
        public BankAccount(int accountNum)
        {
            AccountNum = accountNum;     
        }
        public int AccountNum { get; private set; }
    }
    public class AccountInterest
    {
        public BankAccount Account { get; private set; }
        public AccountInterest(BankAccount account)
        {
            Account = account;
        }
        public double InterestRate
        {
            get { return CalculateInterestRate(); }
        }
        public bool IntroductoryRate
        {
            get { return CalculateInterestRate() < 0.05; }
        }
        public double CalculateInterestRate()
        {
            if (Account.AccountNum > 800)
                return 0.02;
            if (Account.AccountNum > 10 && Account.AccountNum <= 800)
                return 0.03;
            return 0.05;
        }
    }

      代码操作更加清晰，直观。功能单一化。