c++ - C++中的 final类

class Temp
{
private:
    ~Temp() {}
    friend class Final;
};

class Final : virtual public Temp
{
public:
     void fun()
     {
         cout<<"In base";
     }
};

class Derived : public Final
{
};

void main()
{
    Derived obj;
    obj.fun();
}

上面的代码尝试实现不可继承的类(最终)。但是使用上面的代码仍然可以创建派生对象，为什么？

只有将ctor设为私有(private)才能实现所需的功能，我的问题是为什么在dtor私有(private)的情况下无法实现？

最佳答案

好吧，对于此程序(请提供正确的可编译示例)

#include <iostream>

class Temp
{
private:
    ~Temp() {}
    friend class Final;
};

class Final : virtual public Temp
{
public:
    void fun() { std::cout<<"In base"; }
};

class Derived : public Final {};

int main() {
    Derived obj;
    obj.fun();
}

Comeau Online说

Comeau C/C++ 4.3.10.1 (Oct  6 2008 11:28:09) for ONLINE_EVALUATION_BETA2
Copyright 1988-2008 Comeau Computing.  All rights reserved.
MODE:strict errors C++ C++0x_extensions

"ComeauTest.c", line 16: error: "Temp::~Temp()" (declared at line 6) is inaccessible
  class Derived : public Final {
                         ^
          detected during implicit generation of "Derived::Derived()" at line
                    21

"ComeauTest.c", line 16: error: "Temp::~Temp()" (declared at line 6) is inaccessible
  class Derived : public Final {
        ^
          detected during implicit generation of "Derived::~Derived()" at line
                    21

2 errors detected in the compilation of "ComeauTest.c".

因为有疑问，我总是信任como(我只发现过一个错误，但是在其他编译器中却发现了很多错误)，所以我认为VC9(接受代码)出错了。 (我也想从void main()中也使用VC。)