structure.cpp

来自「自己写的c++实现的headfirst中的设计模式」· C++ 代码 · 共 77 行

/* 策略模式
 */

#include <iostream>

using namespace std;

class flyBeheviour
{
public:
	virtual void fly()=0;		//纯虚函数与虚函数
};

class flyble:public flyBeheviour
{
public:
	void fly()
	{
		cout << "I'm flying!"<<endl;
	}
};

class unflyble:public flyBeheviour
{
public:
	void fly()
	{
		cout << "I cannot fly!"<<endl;
	}
};

class duck		//防止实例化？
{
protected:
	//virtual duck();		//wrong!
	flyBeheviour* f;
	
public:
	void fly()
	{
		f->fly();
	}
	
	void setFlyBeheviour(flyBeheviour& f)
	{
		delete this->f;
		this->f=&f;
	}
	
	~duck()
	{
		delete f;
	}
	
};

class normalDuck:public duck
{
public:
	normalDuck()
	{
		f=new flyble;
	}
};

void structure_main()
{
	normalDuck nd;
	nd.fly();
	//nd.setFlyBeheviour(unflyble);
	nd.setFlyBeheviour(*(new unflyble));
	nd.fly();

}