Re: CreateInstance

Hi Ben,

Seems you mean it is vtable which is the root cause of this issue. I do not
agree with you. I have wrote a sample for you to review. You can see even if
no virtual functions, no vtable, no data member, we still can not do the type
conversion. Here is the full code with compile error. I tested in Visual
Studio 2008. Let me know if you have any comments or ideas. Thanks.

BTW: currently, my points is compiler enforce too strict checking of Diamond
issue (duplicate base class) even if there is no change to be ambiguity.
Agree?

#include <iostream>

using namespace std;

class Base {
public:
    int foo() {cout << "Base" << endl;}
};

class Derived1: public Base
{
public:
    int foo() {cout << "Derived1" << endl;}
};

class Derived2: public Base
{
public:
    int foo() {cout << "Derived2" << endl;}
};

class Final: public Derived1, public Derived2 {
public:
    int foo() {cout << "Final" << endl;}
};

int main()
{
    Final f;
    Final* p = &f;
    Base* pb = p; //error C2594: 'initializing' : ambiguous conversions from
'Final *' to 'Base *'
    return 0;
}

regards,
George

"Ben Voigt [C++ MVP]" wrote: