decreator.cpp

自己写的c++实现的headfirst中的设计模式

/* *装饰模式
 */

#include <iostream>
#include <string>

using namespace std;

class Goat
{
private:		//??
	string description;
	
	
	string getDescription()
	{
		return description;
	}

public:
	Goat()	{string description="I'm a goat.";}
	virtual void function()=0;
};

class BlackGoat:public Goat
{
private:
	string description;
	
	string getDescription()
	{
		return description;
	}
public:
	BlackGoat(){string description="I'm a black goat.";}
};

class WhiteGoat:public Goat
{
private:
	string description;
	
	string getDescription()
	{
		return description;
	}
public:
	WhiteGoat()
	{string description="I'm a white goat.";}
		
};
	
	
	


class Decreator:public Goat		//Decreator基类根本没有用，搞不懂为什么还要继承他而不是Goat.添加新函数用？
{
public:
	//virtual void function()=0;
	void extraout()
	{
		cout << "extraout!"<<endl;
	}
};

class Plus:public Decreator
{
private:
	Goat* drt;		//基类指针，因为第一次传入的是Goat
	//换为Decreator后添加for goat的构造函数

public:
	Plus(Goat* drt)		//继承构造函数		//基类指针，因为要支持传入Goat
	{
		this->drt=drt;
	}
	
	void function()
	{
		cout << "I can do plus!"<<endl;
		if(drt!=NULL)	drt->function();
	}
};
	
class Minus:public Decreator
{
private:
	Goat* drt;

public:
	Minus(Goat* drt)		//继承构造函数
	{
		this->drt=drt;
	}
	
	void function()
	{
		cout << "Minus!"<<endl;
		if(drt!=NULL)	drt->function();
	}
};


void decreator_main()
{
	Goat *g=NULL;		//自动NULL？
	g=new Plus(g);
	g=new Minus(g);
	g=new Minus(g);
	Minus k(NULL);
	Goat *p=&k;
	//p->extraout();
	g->function();
	delete g;
}