设计模式-装饰器模式

装饰器Decorator：主要是增加现有类的功能
通过子类实现功能增强的问题：为了增强现有类的功能，通过实现子类的方式，重写接口，是可以完成功能扩展的，但是代码中有太多的子类添加进来了

class Car//抽象基类
{
public:
	virtual void show() = 0;
};

//三个实体的汽车类
class Bmw : public Car {
public:
	void show()
	{
		cout << "这是一辆宝马汽车，配置有：基本配置";
	}
};

class Audi : public Car {
public:
	void show()
	{
		cout << "这是一辆奥迪汽车，配置有：基本配置";
	}
};

class Benz : public Car {
public:
	void show()
	{
		cout << "这是一辆奔驰汽车，配置有：基本配置";
	}
};

//装饰器
class ConcreteDecorator01 : public Car
{
public:
	ConcreteDecorator01(Car *p) : pCar(p) {};
	void show()
	{
		pCar->show();
		cout << ", 定速巡航";
	}
private:
	Car *pCar;
};

class ConcreteDecorator02 : public Car
{
public:
	ConcreteDecorator02(Car *p) : pCar(p) {};
	void show()
	{
		pCar->show();
		cout << ", 自动刹车";
	}
private:
	Car *pCar;
};

class ConcreteDecorator03 : public Car
{
public:
	ConcreteDecorator03(Car *p) : pCar(p) {};
	void show()
	{
		pCar->show();
		cout << ", 车道偏离";
	}
private:
	Car *pCar;
};

int main()
{
	Car *p1 = new ConcreteDecorator01(new Bmw());
	p1 = new ConcreteDecorator02(p1);
	p1->show();
	cout << endl;

	Car *p2 = new ConcreteDecorator02(new Audi());
	p2->show();
	cout << endl;

	Car *p3 = new ConcreteDecorator03(new Benz());
	p3->show();
	cout << endl;

	return 0;
}

这是一辆宝马汽车，配置有：基本配置, 定速巡航, 自动刹车
这是一辆奥迪汽车，配置有：基本配置, 自动刹车
这是一辆奔驰汽车，配置有：基本配置, 车道偏离