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FAQ: What's Wrong with Multiple Inheritance? (was Re: RDF Concepts Reference)

From: <uche.ogbuji@fourthought.com>
Date: Thu, 18 Jan 2001 12:18:45 -0700
Message-Id: <200101181918.MAA24707@localhost.localdomain>
To: Dan Brickley <Daniel.Brickley@bristol.ac.uk>
cc: Dave Beckett <dave.beckett@bristol.ac.uk>, Dennis van der Laan <LaanD@vertis.nl>, www-rdf-interest@w3.org
> > >> rdfs:ConstraintProperty is the only class that is a subclass of
> > >> two other classes.  Why?
> > 
> > To me it looks like an oddity in the rdf class hierarchy and is the
> > only part that means RDF schema implementations have to support
> > multiple inheritance.  Maybe this is required anyway but it isn't
> > explicitly described.  
> > 
> > If it is so clear to you Dennis, why don't you explain it?
> 
> "Multiple inheritance" in RDF is in large part forced on us by having a
> flat space of identifiers (or identifiable objects).

OK, here's a question I seem to have to ask very frequently, but to which I 
never seem to get a useful answer.  What on Earth is wrong with multiple 
inheritance?

It seems that ever since Java came out crowing for some odd reason that it had 
"fixed" C++'s use of MI, the orthodoxy has become that multiple inheritance is 
bad, but I think this is nonsense.

Certainly in RDF it makes the most eminent sense.  Inheritance is a simple 
arc, and I don't see how the cardinality of that particular arc hampers the 
quality of the expression or implementation in any way.


-- 
Uche Ogbuji                               Principal Consultant
uche.ogbuji@fourthought.com               +1 303 583 9900 x 101
Fourthought, Inc.                         http://Fourthought.com 
4735 East Walnut St, Ste. C, Boulder, CO 80301-2537, USA
Software-engineering, knowledge-management, XML, CORBA, Linux, Python
Received on Thursday, 18 January 2001 14:18:56 GMT

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