On Sep 16, 8:29 pm, red floyd <no.s...@here.dude> wrote:
puzzlecracker wrote:
I am kind of confused with the vpointer. Assuming the class has a
virtual function. Would ONE pointer (occupying 16 bits) to virtual
table be create for the class or One for each object? How does this
pointer fit into aligment properties of an object (of the class) or
class itself?
An implementation is not required to provide a vptr or a vtbl. Most
implementations use them, but they are not required to.
If your implementation uses vptr, it would be the natural pointer size
for your platform (most likely *NOT* 16 bits), and each object of that
class would have the vptr. There would be one vtbl for each class, and
each object of that class would point to that vtbl.
For details of how a vptr/vtbl model works, see Lippman's "Inside the
C++ Object Model".
Seems like an overhead, to have one pointer per object, that can
possibly be avoided. All object pointers to a specific derived type
have pointer to the same virtual table. Perhaps we can store that
pointer (as static variable or external) that each object of that
derived class can see/use. Is such construct available or can be
simulate it in C++? Agh, it is really a compiler issue.
information together with the type. The problem with the second is that