从派生类中引用基类成员 [英] Refer base class members from derived class

问题描述

class A {
    public:
        void fa() {
        }
    };

class B : public A{
public:
    void fb() {
    }
};

class C : public A, public B {
public:
    void fc() {
        //call A::fa(), not B::A::fa();
    }
};

如何调用 A :: fa（）从 C :: fc（）函数。

GCC使用直接基础警告C由于模糊性而无法访问，这是否意味着没有直接的方法引用基类成员？

GCC warns withdirect base A inaccessible in C due to ambiguity, does this mean there is no direct way to refer base class members?

推荐答案

一个选项是创建一个存根类，子对象：

One option would be to create a stub class that you can use for casting to the right base class subobject:

struct A {
    void fa() { }
};

struct B : A {
    void fb() { }
};

// Use a stub class that we can cast through:
struct A_ : A { };

struct C : A_, B {
    void fc() {
        implicit_cast<A_&>(*this).fa();
    }
};

其中 implicit_cast 定义为：

template <typename T> struct identity { typedef T type; }

template <typename T>
T implicit_cast(typename identity<T>::type& x) { return x; }

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