新的接口：一个是拷贝给定的对象，另一个是移动对象。

void add_item(const Quote& sale);//左值拷贝void add_item(Quote&& sale);//右值移动

关键点：

1，由于类Quote没有自定义的拷贝控制成员（拷贝构造函数，赋值语句等），所以，编译器才能自动生成移动构造函数，后面要用到编译器生成移动构造函数。

2，由于key是智能指针，所以在方法add_item里必须要有new，问题来了，new谁呢，只能new父类Quote，但是new了Quote后，子类部分就被切除掉了。

3，为了解决在2处的问题，在Quote和它的子类里添加辅助的虚函数，来得到正确的指针。得到了正确的普通指针就可以用普通指针做出智能指针了。

Quote4.h

#ifndef __QUOTE4_H__#define __QUOTE4_H__#include 
    
     class Quote{ public:  Quote() = default;  Quote(const std::string& book, double pri)    :bookNo(book), price(pri){}  std::string isbn() const{return bookNo;}    //调用此方法的对象是左值的时候  virtual Quote* clone() const & {    //调用合成的拷贝构造函数    return new Quote(*this);  }  ///调用此方法的对象是右值的时候  virtual Quote* clone() && {    //调用合成的移动构造函数    return new Quote(std::move(*this));  }  virtual double net_price(std::size_t n)const{    return n * price;  }  virtual void debug()const{    std::cout << bookNo << " " << price << std::endl;  }  virtual ~Quote() = default; private:  std::string bookNo; protected:  double price = 0.0;};class Disc_quote : public Quote{ public:  Disc_quote() = default;  Disc_quote(const std::string& book, double price,         std::size_t qyn, double disc):Quote(book, price),    quantity(qyn), discount(disc){}    double net_price(std::size_t) const override = 0; protected:  std::size_t quantity = 0;//折扣适用的数量  double discount = 0.0;   //折扣率};class Bulk_quote : public Disc_quote{ public:    Bulk_quote() = default;    Bulk_quote(const std::string& book, double price,  std::size_t qyn, double disc)  :Disc_quote(book, price, qyn, disc){}  //调用此方法的对象是左值的时候  Bulk_quote* clone() const & {    //调用合成的拷贝构造函数    return new Bulk_quote(*this);  }  ///调用此方法的对象是右值的时候  Bulk_quote* clone() && {    //调用合成的移动构造函数    return new Bulk_quote(std::move(*this));  }    double net_price(std::size_t) const override;};class Min_quote : public Disc_quote{ public:    Min_quote() = default;  Min_quote(const std::string& book, double price,       std::size_t qyn, double disc)   :Disc_quote(book, price, qyn, disc){}    double net_price(std::size_t) const override;};#endif

Quote4.cpp

#include "Quote4.h"double Bulk_quote::net_price(std::size_t cnt) const{  if(cnt >= quantity){    return cnt * (1 - discount) * price;  }  else{    return cnt * price;  }}double Min_quote::net_price(std::size_t cnt) const{  if(cnt < quantity){    return cnt * (1 - discount) * price;  }  else{    return cnt * price;  }}

Basket2.h

#ifndef __BASKET2_H__#define __BASKET2_H__#include "Quote4.h"#include 
    
     #include 
     
      class Basket{ public:  /*  void add_item(const std::shared_ptr
      
       & sale){    items.insert(sale);  }  */  void add_item(const Quote& sale){    items.insert(std::shared_ptr
       
        (sale.clone()));  }  void add_item(Quote&& sale){    items.insert(std::shared_ptr
        
         (std::move(sale).clone()));  }    double total_receipt(std::ostream&) const; private:  static bool compare(const std::shared_ptr
         
          & lhs, const std::shared_ptr
          
           & rhs){ return lhs->isbn() < rhs->isbn(); } std::multiset
           
            
             , decltype(compare)*> items{compare};};#endif

Basket2.cpp

#include "Basket.h"double print_total(std::ostream& os,           const Quote& item, size_t n);double Basket::total_receipt(std::ostream& os) const{  double sum = 0.0;  for(auto iter = items.cbegin();      iter != items.cend();      iter = items.upper_bound(*iter)){    sum += print_total(os, **iter, items.count(*iter));  }  os << "Total Sale: " << sum << std::endl;  return sum;}

main.cpp

#include "Quote4.h"#include "Basket2.h"#include 
    
     #include 
     
      double print_total(std::ostream& os,           const Quote& item, size_t n){  double ret = item.net_price(n);  os << "ISBN: " << item.isbn()     << " # sold: " << n << " total due: " << ret << std::endl;  return ret;}int main(){  Basket bsk;  Quote q1("01", 100);  Bulk_quote bq1("01", 100, 2, 0.1);  bsk.add_item(Quote("01", 100));  bsk.add_item(Bulk_quote("01", 100, 2, 0.1));  bsk.total_receipt(std::cout);}