测试一个类是否是多态的

We have a sub-project 'commonUtils' that has many generic code-snippets used across the parent project. One such interesting stuff i saw was :-

/*********************************************************************
If T is polymorphic, the compiler is required to evaluate the typeid 
stuff at runtime, and answer will be true.  If T is non-polymorphic, 
the compiler is required to evaluate the typeid stuff at compile time, 
whence answer will remain false
*********************************************************************/
template <class T> 
bool isPolymorphic() { 
   bool answer=false; 
   typeid(answer=true,T()); 
   return answer; 
}

我相信评论并认为它是一个非常有趣的模板，尽管它不是在整个项目中使用.我只是出于好奇而尝试这样使用它...

class PolyBase {
public:
   virtual ~PolyBase(){}
};

class NPolyBase {
public:
   ~NPolyBase(){}
};


if (isPolymorphic<PolyBase>())
  std::cout<<"PolyBase = Polymorphic
";
if (isPolymorphic<NPolyBase>())
  std::cout<<"NPolyBase = Also Polymorphic
";

template <class T> 
bool isPolymorphic() { 
    bool answer=false;
    T *t = new T();
    typeid(answer=true,*t); 
    delete t;
    return answer; 
}