訪问者设计模式是已经有了一组Person对象了，然后不同的訪问者訪问这组对象。会有不同效果。

这些訪问者实际上就是一个能够让Person对象组运行的动作行为等。

至于这些Person对象是怎样运行这些訪问者的动作的，那是已经在特定的不同的Person对象中设计好的。

比方我们的訪问者或许是一些动作集合的类，如：

class Action

{

public:

	string present;

	string gun;

	virtual void drinkBeer(Person *p) = 0;

	virtual void getAGun(Person *p) = 0;

};

依据这个訪问者基类定义不同的訪问动作：

class ActionOne:public Action

{

public:

	ActionOne()

	{

		present = "Alcohol";

		gun = "Laiser";

	}

	void drinkBeer(Person *p);

	void getAGun(Person *p);

};

class ActionTwo:public Action

{

public:

	ActionTwo()

	{

		present = "Beer";

		gun = "Machine Gun";

	}

	void getAGun(Person *p);

	void drinkBeer(Person *p);

};

而Person类则运行动作类的不同动作，也是基类动作的一部分，这样呈现出不同Person运行的行为不一样。

class Person

{

public:

	string something;

	virtual void receivedVisitor(Action *visitor) = 0;

};

class Bill:public Person

{

public:

	Bill()

	{

		something = "food";

	}

	void receivedVisitor(Action *visitor)

	{

		puts("\nVisitor to Bill bring :");

		puts(visitor->present.c_str());

		visitor->drinkBeer(this);

	}

};

class Mark:public Person

{

public:

	Mark()

	{

		something = "Weapon";

	}

	void receivedVisitor(Action *visitor)

	{

		puts("\nVisitor to Mark bring :");

		puts(visitor->gun.c_str());

		visitor->getAGun(this);

	}

};

使用一个类来存放这些对象：

class House

{

protected:

	vector<Person *> vps;

public:

	void addPerson(Person *p)

	{

		vps.push_back(p);

	}

	void receiver(Action *visitor)

	{

		for (int i = 0; i < (int)vps.size(); i++)

		{

			vps[i]->receivedVisitor(visitor);

		}

	}

	~House()

	{

		for (int i = 0; i < (int)vps.size(); i++)

		{

			delete vps[i];

		}

	}

};

最后就在这个类对象中存放须要被訪问的对象，然后使用动作类来訪问这些对象。

总的来说也是思想并不太难的一个设计模式，可是要非常好实现还是不太easy的。

所有代码例如以下：

#include <stdio.h>

#include <iostream>

#include <string>

#include <vector>

using namespace std;

class Person;

class Action

{

public:

	string present;

	string gun;

	virtual void drinkBeer(Person *p) = 0;

	virtual void getAGun(Person *p) = 0;

};

class ActionOne:public Action

{

public:

	ActionOne()

	{

		present = "Alcohol";

		gun = "Laiser";

	}

	void drinkBeer(Person *p);

	void getAGun(Person *p);

};

class ActionTwo:public Action

{

public:

	ActionTwo()

	{

		present = "Beer";

		gun = "Machine Gun";

	}

	void getAGun(Person *p);

	void drinkBeer(Person *p);

};

class Person

{

public:

	string something;

	virtual void receivedVisitor(Action *visitor) = 0;

};

class Bill:public Person

{

public:

	Bill()

	{

		something = "food";

	}

	void receivedVisitor(Action *visitor)

	{

		puts("\nVisitor to Bill bring :");

		puts(visitor->present.c_str());

		visitor->drinkBeer(this);

	}

};

class Mark:public Person

{

public:

	Mark()

	{

		something = "Weapon";

	}

	void receivedVisitor(Action *visitor)

	{

		puts("\nVisitor to Mark bring :");

		puts(visitor->gun.c_str());

		visitor->getAGun(this);

	}

};

void ActionOne::drinkBeer(Person *p)

{

	puts("Let's eat something");

	puts(p->something.c_str());

}

void ActionOne::getAGun(Person *p)

{

	puts("Let's gear up");

	puts(p->something.c_str());

}

void ActionTwo::getAGun(Person *p)

{

	puts("Let's gear up");

	puts(p->something.c_str());

}

void ActionTwo::drinkBeer(Person *p)

{

	puts("Let's eat something");

	puts(p->something.c_str());

}

class House

{

protected:

	vector<Person *> vps;

public:

	void addPerson(Person *p)

	{

		vps.push_back(p);

	}

	void receiver(Action *visitor)

	{

		for (int i = 0; i < (int)vps.size(); i++)

		{

			vps[i]->receivedVisitor(visitor);

		}

	}

	~House()

	{

		for (int i = 0; i < (int)vps.size(); i++)

		{

			delete vps[i];

		}

	}

};

int main()

{

	House house;

	house.addPerson(new Bill);

	house.addPerson(new Mark);

	ActionTwo gun;

	ActionOne drink;

	house.receiver(&gun);

	house.receiver(&drink);

	return 0;

}

运行：

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