标签：style blog io color os 使用 sp on div
Visitor模式在不破坏类的前提下，为类提供增加新的新操作。
Visitor模式经常用于将更新的设计封装在一个类中，并且由待更改的类提供一个接受接口，其关键技术在于双分派技术，Element类提供接口，通过Accept实现具体使用哪一个具体的Visit操作；
#include <iostream>
using namespace std;
class Element;
class Visitor
{
public:
virtual ~Visitor(){}
virtual void visitConElemA(Element* elm)=0;
virtual void visitConElemB(Element* elm)=0;
protected:
Visitor(){}
};
class ConcreteVisitorA:public Visitor
{
public:
ConcreteVisitorA(){};
virtual ~ConcreteVisitorA(){};
void visitConElemA(Element* elm){cout<<"visit A";}
void visitConElemB(Element* elm){cout<<"visit B";}
};
class ConcreteVisitorB:public Visitor
{
public:
ConcreteVisitorB(){};
virtual ~ConcreteVisitorB(){};
void visitConElemA(Element* elm){cout<<"visit A";}
void visitConElemB(Element* elm){cout<<"visit B";}
};
class Element
{
public:
virtual ~Element(){};
virtual void Accept(Visitor* vis)=0;
protected:
Element(){};
};
class ConcreteElementA:public Element
{
public:
ConcreteElementA(){}
~ConcreteElementA(){}
void Accept(Visitor* vis)
{
cout<<"This is A interface "<<endl;
vis->visitConElemA(this);
}
};
class ConcreteElementB:public Element
{
public:
ConcreteElementB(){}
~ConcreteElementB(){}
void Accept(Visitor* vis)
{
cout<<"This is B interface ";
vis->visitConElemB(this);
}
};
void main()
{
Visitor* vis=new ConcreteVisitorA();
Element* elm=new ConcreteElementA();
elm->Accept(vis);
delete elm;
delete vis;
}标签：style blog io color os 使用 sp on div
原文地址：http://blog.csdn.net/yc7369/article/details/41812559
