第一章：重构，第一个案例(读书笔记系列2) _实验三代码重构实践对书第一章的例子-优快云博客

本文链接：https://blog.youkuaiyun.com/Last_Impression/article/details/4748954

本文通过一个电影租赁系统的案例，展示了如何逐步进行代码重构的过程，包括分解复杂函数、改善数据结构及添加新功能等步骤。

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1.2重构的第一步
为即将修改的代码建立一组可靠的测试环境，在重构之前，首先检查自己是否有一套可靠的测试机制．这些测试必须有自我检验(self-checking)能力

1.3分解并重组Statement()

Movie.h

#pragma once #include <string> class Movie { public: typedef enum _MovieType { eCHILDREN = 2, //儿童片 eREGUIAR = 0, //普通片 eNEW_RELEASE = 1 //新片 }MovieType; public: Movie(std::string title, int priceCode) { m_title = title; m_priceCode = priceCode; }; void SetPriceCode(int arg) { m_priceCode = arg; }; int GetPriceCode(void) { return m_priceCode; }; std::string GetTitle(void) { return m_title; }; private: std::string m_title;//名称 int m_priceCode;//价格代号 };

Rental.h

#pragma once #include "Movie.h" class Rental { public: Rental(Movie* pMovie,int rented) { m_pMovie = pMovie; m_daysRented = rented; }; int GetDaysRented(void) { return m_daysRented; }; Movie* GetMovie(void) { return m_pMovie; }; ////////////////////////////////////////////////////////////////////////// //v1.3分解并重组: public: double GetCharge(void) { double result = 0.0; int priceCode = this->GetMovie()->GetPriceCode(); switch(priceCode) { case Movie::eCHILDREN://儿童片 result += 2; break; case Movie::eREGUIAR://普通片 result += 1.5; if (this->GetDaysRented() > 3) { result += (this->GetDaysRented() - 3) * 1.5; } break; case Movie::eNEW_RELEASE://新片 result = this->GetDaysRented() * 3; break; default: result += 2; break; } return result; }; //常客积点计算 int GetFrequentRenterPoints(void) { if ( GetMovie()->GetPriceCode() == Movie::eNEW_RELEASE && GetDaysRented() > 1) { return 2; } else { return 1; } }; ////////////////////////////////////////////////////////////////////////// private: Movie* m_pMovie;//影片 int m_daysRented;//租期 };

Customer.h

#pragma once #include <vector> #include "Rental.h" class Customer { ////////////////////////////////////////////////////////////////////////// //v1.3分解并重组:迭代器类型的声明 public: typedef std::vector<Rental*>::const_iterator RentalIterator; ////////////////////////////////////////////////////////////////////////// public: Customer(std::string name) { m_name = name; }; void AddRental(Rental* arg) { m_Rentals.push_back(arg); }; std::string GetName(void) { return m_name; }; std::string Statement(void); ////////////////////////////////////////////////////////////////////////// //v1.3分解并重组 public: //添加功能 std::string HtmlStatement(void); private: //常客积点计算总数 double GetTotalFrequentRenterPoints(void); //常客积点计算总消费金额 double GetTotalCharge(void); ////////////////////////////////////////////////////////////////////////// private: std::string m_name; //姓名 std::vector<Rental*> m_Rentals; //租借记录 };

Customer.cpp

#include "Customer.h" #include <iostream> #include "Common.h" std::string Customer::Statement(void) { RentalIterator iterRentals = m_Rentals.begin(); std::string result = "Rental Record for" + this->GetName() + "/n"; while (iterRentals != m_Rentals.end()) { //显示此笔数据 result += "/t" + (*iterRentals)->GetMovie()->GetTitle() + "/t" + CommonFunction::ConvertToString<double>((*iterRentals)->GetCharge()) + "/n"; ++iterRentals; } //结尾打映 result += "Amount owed is " + CommonFunction::ConvertToString<double>(GetTotalCharge()) + "/n"; result += "You earned " + CommonFunction::ConvertToString<double>(GetTotalFrequentRenterPoints()) + " frequent renter points"; return result; }; //添加功能 std::string Customer::HtmlStatement(void) { RentalIterator iterRentals = m_Rentals.begin(); std::string result = "<H1>Rental Record for" + this->GetName() + "</H1>/n"; while (iterRentals != m_Rentals.end()) { result += (*iterRentals)->GetMovie()->GetTitle() + ": " + CommonFunction::ConvertToString<double>((*iterRentals)->GetCharge()) + " /n"; ++iterRentals; } result += "Amount owed " + CommonFunction::ConvertToString<double>(GetTotalCharge()) + "/n"; result += "You earned " + CommonFunction::ConvertToString<double>(GetTotalFrequentRenterPoints()) + " frequent renter points"; return result; }; //query method double Customer::GetTotalFrequentRenterPoints(void) { int result = 0; RentalIterator iterRentals = m_Rentals.begin(); while (iterRentals != m_Rentals.end()) { //累加常客积点 result += (*iterRentals)->GetFrequentRenterPoints(); ++iterRentals; } return result; }; //query method double Customer::GetTotalCharge(void) { double result = 0; RentalIterator iterRentals = m_Rentals.begin(); while (iterRentals != m_Rentals.end()) { result += (*iterRentals)->GetCharge(); ++iterRentals; } return result; };

改进后的图

对象图

客户端代码，里面有变更的履历

////////////////////////////////////////////////////////////////////////// //v1.3分解并重组: // step1:用Extract Method找出逻辑泥团（logical clump）把switch提炼到独立的函数中去, // 函数暂时定义为AmountFor // step2:在AmountFor中,更改临时变量名称，便于理解代码 // step3:搬移金额计算代码，AmountFor的内容转移到GetChange // step4:找出Customer中对AmountFor的引用，改成迭代器+GetChange // step5:在Customer.cpp中，(*iterRentals)->GetCharge()替换thisAmount,消去不必要的临时变量 // step6:提炼常客积点计算代码，增加到getFrequentRenterPoints // step7:去除临时变量，利用所谓的query method来取代totalAmount和frequentRenterPoints // step8:添加功能:HtmlStatement ////////////////////////////////////////////////////////////////////////// #include "stdafx.h" #include "Customer.h" #include <iostream> int _tmain(int argc, _TCHAR* argv[]) { Movie* movie1 = new Movie("赤壁", 1); Movie* movie2 = new Movie("风声", 0); Movie* movie3 = new Movie("建国大业", 0); Rental* rental1 = new Rental(movie1, 1); Rental* rental2 = new Rental(movie2, 2); Rental* rental3 = new Rental(movie3, 3); Customer* custom = new Customer("ZZ"); custom->AddRental(rental1); custom->AddRental(rental2); custom->AddRental(rental3); std::cout << custom->Statement() << std::endl; delete movie1; delete movie2; delete movie3; delete rental1; delete rental2; delete rental3; delete custom; return 0; }