Subject: the 'Extends' clause

From: "Andreas Polyrakis" <[email-masked]>
Date: Wed, 14 Mar 2001 16:51:41 -0500

Hi,

one simple question on the SPPI:
Suppose that there is a class A, which is extended by two classes B and C.
It there a way to denote that instances of A MUST be extended by either
an instance of B or an instance of C? So that that for each PRI in A,
either a PRIs in B or in C exist?

thanks in advance,
Andreas

---

From: "Sahita, Ravi" <[email-masked]>
Date: Wed, 14 Mar 2001 14:14:40 -0800

Andreas,

What you are specifying here, is using class A as an abstract class which
cannot
be instantiated by itself. You can't specify this by using the EXTENDS 
clause, but you could force this relationship at the implementation level,
i.e an 
instance of A cannot be received/sent if an instance of B OR C with the same
instance id is not received/sent.

Ravi

-----Original Message-----
From: Andreas Polyrakis [mailto:[email-masked]]
Sent: Wednesday, March 14, 2001 1:52 PM
To: [email-masked]
Subject: the 'Extends' clause

Hi,

thanks in advance,
Andreas