On Oct 29, 4:46 am, "Daniel T." <danie...@earthlink.net> wrote:
Joshua Maurice <joshuamaur...@gmail.com> wrote:
With this multiple inheritance design, I would guess that you
probably want to virtually inherit from Fooer as well (not done
in the above code).
Virtual inheritance would only be necessary if Fooer had
member-variables. Inheriting interfaces (classes with only pure
virtual functions and no member-variables,) does not require
virtual inheritance.
I'm not so sure about this. Let me think about it.
At the very least, if you inherit from such an "interface" class
twice, then you will have two distinct base class sub-objects, and
they will have distinct addresses. (IIRC, the intent of the
standard is that two objects (complete or sub-objects) of the same
type should be distinct objects iff they have distinct addresses.
However, I recall that the wording might have been changed to
remove this requirement. Not sure what the situation is.) I would
think that that is counter-intuitive. I think that a programmer
might simply assume that if he has two distinct Fooer (sub)objects
(distinct according to distinct addresses), then he has two
distinct complete objects. However, such inference would be
incorrect without virtual inheritance.
case. A base class that contains no data members need not have a