Xref: utzoo comp.lang.c++:7846 gnu.g++:874
Path: utzoo!attcan!uunet!mcsun!ukc!keele!nott-cs!gas
From: gas@cs.nott.ac.uk (Alan Shepherd)
Newsgroups: comp.lang.c++,gnu.g++
Subject: static data members and derived classes (AT&T v g++)
Message-ID: <50037@robin.cs.nott.ac.uk>
Date: 31 May 90 08:57:40 GMT
Sender: root@cs.nott.ac.uk
Reply-To: gas@cs.nott.ac.uk (Alan Shepherd)
Organization: Computer Science, Nottingham Univ., UK.
Lines: 35

I apologize if I'm asking a lot of banal questions, but no-one seems
to answer !  I'd rather have 60 answers than none at all.

I would like the position regarding static members and derived classes
clarified.  Consider a class 'a' with a protected static int 'number':

class a
{
	protected:
		static int number;
}

Now derive a class `b' from 'a':

class b: public a
{
}

From my understanding of the AT&T reference manual for release 2.0
($11.5), I should now be able to refer to b::number.  Unfortunately,
cfront complains that b doesn't have a member 'number'.  This doesn't
appear to make sense.  However, g++ compiles fine, but does something
even more peculiar.

int a::fred =3;
int b::fred =4;

The above two statements leave both a and b with the value 3 for fred.
However, during normal execution (i.e. after main) changing the value
of a::fred or b::fred sets them both to be the same value.  This means
that there is definitely a bug in the way g++ initialises the static
members before main and the policy seems odd.  I would rather have
class 'b' inherit its own distinct static member.

Alan Shepherd