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动态声明子类
#include <iostream>
#include <cstdlib>
using namespace std;
class BaseClass
{
public:
BaseClass()
{
cout<<"BaseClass Construct"<<endl;
}
virtual ~BaseClass()
{
cout<<"BaseClass Destruct"<<endl;
}
virtual void TestFunction()
{
cout<<"BaseClass TestFunction"<<endl;
}
protected:
int Test;
};
class SonClass : public BaseClass
{
public:
SonClass()
{
cout<<"SonClass Construct"<<endl;
}
virtual ~SonClass()
{
cout<<"SonClass Destruct"<<endl;
}
virtual void TestFunction()
{
cout<<"SonClass TestFunction"<<endl;
}
};
typedef void *LPVOID;
template<class _baseClass, class _derivedClass>
bool DoDynamicSubclassing(_baseClass *pBaseObj)
{
if(pBaseObj)
{
static_assert(sizeof(_baseClass) == sizeof(_derivedClass), "DynamicSubclassing to _derivedClass must not have its own members");
_derivedClass _derivedClassinstance;
LPVOID *pBaseVirtPtr = (LPVOID*)pBaseObj, *pDerivedVirtPtr = (LPVOID*)&_derivedClassinstance;
//assign the virtual ptr of the derived class
*pBaseVirtPtr = *pDerivedVirtPtr;
return true;
}
return false;
}
int main()
{
BaseClass *Test = new BaseClass;
cout << *(int*)Test << endl;
DoDynamicSubclassing<BaseClass, SonClass>(Test);
Test->TestFunction();
cout << *(int*)Test << endl;
cout << " ————————- " <<endl;
BaseClass aaaa;
cout << *(int*)&aaaa << endl;
DoDynamicSubclassing<BaseClass, SonClass>(&aaaa);
aaaa.TestFunction();
cout << *(int*)&aaaa << endl;
return 0;
}blog link 动态声明子类