Effective C++ Item 34 区分接口继承与实现继承

本文为senlie原创，转载请保留此地址：http://blog.csdn.net/zhengsenlie

关联条款 Item 36

接口继承和实现继承不同。在 public 继承下， derived classes 总是继承 base class 的接口

class Shape{
public:
	virtual void draw() const = 0;
	virtual void error(const std::string &msg);
	int objectID() const;
	//...
};


class Rectangle: public Shape{...};
class Ellipse: public Shape{...};

class AirPort{...};
class AirPlane{
public:
	virtual void fly(const AirPort &destination);
	//...
};
void AirPort::fly(const AirPort &destination){
	//缺省代码，将飞机飞至指定的目的地
}
class ModelA: public AirPlane {...};
class ModelB: public AirPlane {...};


class ModelC: public AirPlane {
	... // 未声明 fly 函数， 但C型飞机的飞行方式与A，B不同。
};


AirPort PDX(...);
AirPlane *pa = new ModelC;
//...
pa->fly(PDX); //调用 AirPlane::fly

class AirPlane{
public:
	virtual void fly(const AirPort &destination) = 0;
	//...
protected: // protected 因为客户端不需要在意飞机能不能飞
	void defaultFly(const AirPort &destination); //Item 36
};


void AirPlane::defaultFly(const AirPlane &destination){
	//缺省代码，将飞机飞至指定的目的地
}


class ModelA: public AirPlane{
public:
	virtual void fly(const AirPort &destination){
		defaultFly(destination);
	}
	//...
};


class ModelB: public AirPlane{
public:
	virtual void fly(const AirPort &destination){
		defaultFly(destination);
	}
	//...
};


class ModelC: public AirPlane{
public:
	virtual void fly(const AirPort &destination);
	//...
};


void ModelC::fly(const AirPort &destination){ // pure virtual 函数迫使  ModelC 必须提供自己的 fly 版本
	//...
}

class AirPlane{
public:
	virtual void fly(const AirPort &destination) = 0;
	//...
protected: // protected 因为客户端不需要在意飞机能不能飞
	void defaultFly(const AirPort &destination); //Item 36
};


void AirPlane::fly(const AirPlane &destination){ //pure virtual 函数实现
	//缺省代码，将飞机飞至指定的目的地
}


class ModelA: public AirPlane{
public:
	virtual void fly(const AirPort &destination){
		AirPlane::fly(destination);
	}
	//...
};


class ModelB: public AirPlane{
public:
	virtual void fly(const AirPort &destination){
		AirPlane::fly(destination);
	}
	//...
};


class ModelC: public AirPlane{
public:
	virtual void fly(const AirPort &destination);
	//...
};


void ModelC::fly(const AirPort &destination){ // pure virtual 函数迫使  ModelC 必须提供自己的 fly 版本
	//...
}

Effective C++ Item 34 区分接口继承与实现继承,布布扣,bubuko.com

Effective C++ Item 34 区分接口继承与实现继承

原文：http://blog.csdn.net/zhengsenlie/article/details/37723787