访问者模式

打包员
在我们课堂上的“购物车”的例子中，增加一个新的访问者：打包员，负责对购物车中货物装包。

#include <iostream>
#include <vector>
#include <string>
using namespace std;

class Visitor;
class Apple;
class Book;
//抽象产品类
class Product{
public:
virtual void accept(Visitor *visitor){};
};

//抽像访问者
class Visitor{
protected:
string name;
public:
void setName(string name){
this->name = name;
}
virtual void visit(Apple *apple){}
virtual void visit(Book *book){}
};
class Packager:public Visitor{
public:
void visit(Apple *apple) override {
cout<<"打包员"+name+"打包苹果"<<endl;
}
void visit(Book *book) override {
cout<<"打包员"+name+"打包书籍"<<endl;
}
};
//具体产品类Apple
class Apple: public Product{
public:
void accept(Visitor *visitor){
visitor->visit(this);
}
};
//具体产品类Book
class Book:public Product{
public:
void accept(Visitor *visitor){
visitor->visit(this);
}
};
//购物车类BuyBasket
class BuyBasket{
private:
vector<Product*> list;
public:
void accept(Visitor *visitor){
// vector<Product>::iterator i;
// for (i = list.begin(); i != list.end(); ++i) { //用迭代器遍历容器
// i->accept(visitor);
// }
for(int i=0;i<list.size();i++){
list[i]->accept(visitor);
}
}
void addProduce(Product *product){
list.push_back(product);
}
};

int main(){
Book *b1 = new Book();
Book *b2 = new Book();
Apple *a1 = new Apple();
Packager *visitor = new Packager();

BuyBasket basket;
basket.addProduce(b1);
basket.addProduce(b2);
basket.addProduce(a1);

string name = "小明";
visitor->setName(name);
basket.accept(visitor);
}