虚函数在私有或保护继承 [英] virtual function in private or protected inheritance

问题描述

很容易理解公共继承中的虚函数。

It's easy to understand the virtual function in public inheritance. So what's the point for virtual function in private or protected inheritance?

例如：

class Base {
public:
virtual void f() { cout<<"Base::f()"<<endl;}
};

class Derived: private Base {
public: 

void f() { cout<<"Derived::f()"<<endl;}

};

这是否仍然称为覆盖？这种情况的用途是什么？这两个f（）的关系是什么？

Is this still called overriding? What's the use of this case? What's the relationship of these two f()?

谢谢！

推荐答案

私有继承只是一种实现技术，不是一种关系，正如Scott Meyers在Effective C ++中所解释的：

Private inheritance is just an implementation technique, not an is-a relationship, as Scott Meyers explains in Effective C++:

class Timer {
public:
    explicit Timer(int tickFrequency);
    virtual void onTick() const; // automatically called for each tick
    ...
};

class Widget: private Timer {
private:
    virtual void onTick() const; // look at Widget private data
    ...
};

小部件客户端不应该能够在Widget上调用onTick，因为这不是概念小部件界面。

Widget clients shouldn't be able to call onTick on a Widget, because that's not part of the conceptual Widget interface.

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