2.2 搬移字段

 1 // 重构前
 2 class Account
 3 {
 4 public:
 5     double interestForAmount_days(double amount, int days)
 6     {
 7         return m_dInterestRate * amount * days / 365;
 8     }
 9 
10 private:
11     AccountType m_type;
12     double m_dInterestRate; // 利率随类型变化，所以准备搬移该字段
13 };

// 重构后
class Account
{
public:
    double interestForAmount_days(double amount, int days)
    {
        return m_type.getInterestRate() * amount * days / 365;
    }

private:
    AccountType m_type;
};

class AccountType
{
public:
    double getInterestRate()
    {
        return m_dInterestRate;
    }
    void setInterestRete(double dValue)
    {
        m_dInterestRate = dValue;
    }

private:
    double m_dInterestRate; // 利率随类型变化，所以准备搬移该字段
};