[Top] [All Lists]

Re: [ontolog-forum] Heterarchy & Hierarchy, oh my my

To: "[ontolog-forum] " <ontolog-forum@xxxxxxxxxxxxxxxx>
From: "Christopher Spottiswoode" <cms@xxxxxxxxxxxxx>
Date: Mon, 5 May 2008 21:22:56 +0200
Message-id: <02b501c8aee5$76719c40$0100a8c0@Dev>
From: "Ron Wheeler" <rwheeler@xxxxxxxxxxxxxxxxxxxxx>
> The origin of this discussion was a BOM (bill of 
> materials) problem which is well known to require a 
> multiple inheritance model of arbitrary depth.    (01)

"Well known"?  Yes, it is, I suppose, "well known":  it is 
indeed a very common fallacy that BOM involves inheritance, 
and whether it's single or multiple is not the issue.  One 
sees it continually in bad OO teaching in otherwise 
respectable quarters, and even in so-called "OO" 
environments (where they often call it "interface 
inheritance"), that the "contains" relationship is regarded 
as mediating inheritance, whereas inheritance is of course a 
matter of the "isA" relationship.  Fortunately for the 
perpetrators, though, their OO is usually so perverted that 
nobody seem to notice, or care.    (02)

By the way (and I must be getting rather predictable in this 
sort of comment...), in the coming "5th instalment" of my 
"MACK basics" series you will start seeing some nice 
examples of the striking advantages of proper inheritance, 
very insistently involving the "isA" relationship, which, as 
it happens, is usefully orthogonal to "contains".    (03)

Sorry, Ron, to use you in this way, but I hope it is evident 
in my comments that you can't really be blamed!  (You see, I 
can be really liberal and blame your environment...)    (04)

Christopher     (05)

Message Archives: http://ontolog.cim3.net/forum/ontolog-forum/  
Subscribe/Config: http://ontolog.cim3.net/mailman/listinfo/ontolog-forum/  
Unsubscribe: mailto:ontolog-forum-leave@xxxxxxxxxxxxxxxx
Shared Files: http://ontolog.cim3.net/file/
Community Wiki: http://ontolog.cim3.net/wiki/ 
To Post: mailto:ontolog-forum@xxxxxxxxxxxxxxxx    (06)

<Prev in Thread] Current Thread [Next in Thread>