class parent
{
public:
typedef void (parent:: *pfn) ();
parent() : m_p(this)
{
}
virtual ~parent(){}
void prints()
{
std::cout << "parent!" << std::endl;
}
void setcallback(pfn pf)
{
m_pfn = pf;
(this->*m_pfn)(); //回調(diào)，輸出child!
}
pfn m_pfn;
};
class child : public parent
{
public:
child()
{
m_pfn = static_cast<void (parent::*)()>(prints); //這里類型必須匹配(利用static_cast)
}
~child(){}
void prints()
{
std::cout << "child!" << std::endl;
}
void _callback()
{
(this->*m_pfn)(); //回調(diào)，輸出child!
setcallback(m_pfn);
}
int a;
pfn m_pfn;
};
void main()
{
parent *pt;
child onechild;
pt = &onechild;
onechild._callback();
}