Re: call base class function or derived class function

"Igor Tandetnik" <>
Tue, 18 Mar 2008 07:58:50 -0400
"George" <> wrote in message

That's true... does that definition get entered into the v-table


Since we can not instantise a abstract class with pure virtual
function, how could we check whether the pure function is in vtable
or not?

You could a) look at vtable under debugger, or b) try to call the
virtual function from base class constructor (which, technically,
exhibits undefined behavior, but on MSVC it produces a useful

Can we develop some code to verify from RTTI point of view whether or
not pure virtual function is in vtable or not?

I don't understand this question. What does RTTI have to do with

There is no way for a conforming program to call an implementation of a
pure virtual function via virtual dispatch (it is only possible by using
a qualified name, which suppresses virtual dispatch).

Further, your question doesn't make sense from the C++ standard point of
view. The standard never says that virtual functions must be implemented
using a vtable or, indeed, any other specific mechanism. It only
describes how such functions should behave. It's up to the compiler to
implement this behavior in any way it chooses. So any discussion of
vtables is necessarily implementation-specific.
With best wishes,
    Igor Tandetnik

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