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};