第一章：重构，第一个案例(读书笔记系列1)

1.1起点
这是一个影片出租店用的程序，计算每一位顾客的消费金额并打印报表statement
操作者告诉程序：顾客租了哪些影片，租期多长，程序便根据租赁时间和影片类型出费用．
影片有三类：儿童片，普通片，新片．除了计算费用，还要为常客计算点数，点数会随着[租片种类是否为新片]而有所不同

以下是代码，的确如作者所说的，statement做了太多的事情而且也很难维护了。

提示：如果你发现自己需要为程序添加一个特性，而代码结构使你无法很方便地那么做
那就要先重构那个程序，使特征的添加比较容易进行，然后再添加特征．

Movie.h

#pragma once #include <string> class Movie { public: typedef enum _MovieType { eCHILDREN, //儿童片 eREGUIAR, //普通片 eNEW_RELEASE //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; }; private: Movie* m_pMovie;//影片 int m_daysRented;//租期 };

Customer.h

#pragma once #include <vector> #include "Rental.h" class Customer { 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); private: std::string m_name; //姓名 std::vector<Rental*> m_Rentals; //租借记录 std::vector<Rental*>::iterator m_iterRentals; };

Customer.cpp

#include "Customer.h" #include <iostream> #include "Common.h" std::string Customer::Statement(void) { double totalAmount = 0.0; //总消费金额 int frequentRenterPoints = 0; //常客积点 m_iterRentals = m_Rentals.begin(); std::string result = "Rental Record for" + this->GetName() + "/n"; while (m_iterRentals != m_Rentals.end()) { double thisAmount = 0.0; int priceCode = (*m_iterRentals)->GetMovie()->GetPriceCode(); switch(priceCode) { case Movie::eCHILDREN://儿童片 thisAmount += 2; break; case Movie::eREGUIAR://普通片 thisAmount += 1.5; if ((*m_iterRentals)->GetDaysRented() > 3) { thisAmount += ((*m_iterRentals)->GetDaysRented() - 3) * 1.5; } break; case Movie::eNEW_RELEASE://新片 thisAmount = (*m_iterRentals)->GetDaysRented() * 3; break; default: thisAmount += 2; break; } //累加常客积点 frequentRenterPoints++; //add bonus for a two day new release rental if (priceCode == Movie::eNEW_RELEASE && (*m_iterRentals)->GetDaysRented() > 1) { frequentRenterPoints++; } //显示此笔数据 result += "/t" + (*m_iterRentals)->GetMovie()->GetTitle() + "/t" + CommonFunction::ConvertToString<double>(thisAmount) + "/n"; totalAmount += thisAmount; ++m_iterRentals; } //结尾打映 result += "Amount owed is " + CommonFunction::ConvertToString<double>(totalAmount) + "/n"; result += "You earned " + CommonFunction::ConvertToString<double>(frequentRenterPoints) + " frequent renter points"; return result; };

Common.h

#pragma once #include <string> #include <iostream> #include <sstream> class CommonFunction { public: template <class T> static std::string ConvertToString(T value) { std::stringstream ss; ss << value; return ss.str(); }; };

客户端的调用

#include "Customer.h" #include <iostream> int _tmain(int argc, _TCHAR* argv[]) { Movie* movie1 = new Movie("赤壁", 1); Movie* movie2 = new Movie("风声", 2); Movie* movie3 = new Movie("建国大业", 3); 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; }

最后

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