c++ - 为什么我不能在派生类重写函数中调用 protected 虚拟基类函数？

Question

class Base
{
protected:
    virtual void show()
    {
        // Do some stuff.
    }
};

class Derived : public Base
{
protected:
    virtual void show()
    {
        // Do some stuff.
    }
};

class Derived_2 : public Derived
{
protected:
    virtual void show()
    {
        this->show();    // error: Base::show() is in accessible
        show();          // error: Base::show() is in accessible
        Derived::show(); // error: Base::show() is in accessible
    }
};

在上述情况下，调用虚拟基类函数(在派生类中被覆盖)会产生错误。

Answer 1

我能找到的唯一错误是您从自身调用 show 导致无限递归并以堆栈溢出错误结束。

但是这段代码编译并运行时甚至没有警告:

class Derived_2 : public Derived
{
public:
    virtual void show()
    {
        //this->show();    // infinite recursion => stack overflow
        Base::show();    // ok calls show() from Base
        Derived::show();    // ok calls show() from Derived
        std::cout << "Derived2" << std::endl;
    }
};

(我声明它是公开的，以便在我的测试中直接调用它)