Hi, Eljay,
Thanks for the reply.
A private virtual function allows a derived class to implement behavior that
is used by the base class. See C++PL 24.3.2.1
Thanks for the reference. It is good to go back to the C++ bible and refresh my
memory. :)
But it is the fact that Base::fun() is public surprised me, which isn't covered
by C++PL.
The situation you are describe relies on a happenstance where cavalier
casting that relies on the serendipity that the signatures in the vptrtbl
will happen to be in the same offset for the derived class as in the base
class, and thus casting-with-the-big-hammer avoids the compiler catching the
breach of access.
This is my first suspect. So I tried to add some other member functions into
Base class, but failed to disturb the coincidence. Also, this works on both GCC
2.96 and MS C++ .NET, so I assume it is not compiler dependent.
Casting in such a fashion is a source of bugs. Should be avoided.
I strongly agree with you on this, and this is why I hoped the compiler would
catch this in compile time and was suprised that it didn't.
Thanks again for the discussion.
Liguo
