C从具有相同虚函数名称的多个基类继承

class A
{
    virtual void foo() = 0;
};

class B
{
    virtual void foo() = 0;
};

class C : public A, public B
{
    //virtual void A::foo(){}
    //virtual void B::foo(){}

    virtual void A::foo();
    virtual void B::foo();
};

void C::A::foo(){}
void C::B::foo(){}

int main()
{
    C c;
    return 0;
}

使用注释部分时可以,但是当我尝试在类声明之外编写定义时,编译器会报告错误.
我正在使用MSVC11编译器,有谁知道怎么写这个？
我需要将代码移动到cpp文件中.

谢谢~~

[class.virtual] / 2

If a virtual member function vf is declared in a class Base and in a class Derived, derived directly or indirectly from Base, a member function vf with the same name, parameter-type-list, cv-qualification, and ref-qualifier (or absence of same) as Base::vf is declared, then Derived::vf is also virtual (whether or not it is so declared) and it overrides Base::vf.

正如我在评论中已经说过的那样,[dcl.meaning] / 1禁止在(成员)函数的声明中使用qualified-id：

When the declarator-id is qualified, the declaration shall refer to a previously declared member of the class or namespace to which the qualifier refers […]”

因此任何虚拟的空虚X :: foo();作为C内部的声明是非法的.

代码

class C : public A, public B
{
    virtual void foo();
};

是AFAIK覆盖foo的唯一方法,它将覆盖A :: foo和B :: foo.对于A :: foo和B :: foo,除了引入另一个继承层之外,没有办法对其进行两种不同的覆盖：

#include <iostream>

struct A
{
    virtual void foo() = 0;
};

struct B
{
    virtual void foo() = 0;
};

struct CA : A
{
    virtual void foo() { std::cout << "A" << std::endl; }
};

struct CB : B
{
    virtual void foo() { std::cout << "B" << std::endl; }
};

struct C : CA, CB {};

int main() {
    C c;
    //c.foo();  // ambiguous

    A& a = c;
    a.foo();

    B& b = c;
    b.foo();
}