Due to popular demand, I've updated the "C++ background: Static,
reinterpret and C-Style casts"
article. The update clarifies that the compiler may put the virtual
function table (if it uses one) where it wants. The only guarantee by
the C++ standard is that members inside a single declaration block
private:) will not get reordered. I remember that the fact
that C++ does not make any stronger guarantees will enable things like
deriving a class from an object which is hosted on a different heap and
still have some part on another heap -- for example, having a class
which is in part a .NET object and lives on the garbage collected heap
and the other part is native and lives on the normal heap.
[Update] Found it:
Others had often questioned the use-fulness of C++'s leaving that implementation door open for the future, but the mixed type design -- where parts of the same logical object must be on different physical heaps -- vindicates Bjarne's design judgment.
from Herb Sutter's C++/CLI Rationale, page 18.