Path: newssvr20.news.prodigy.com!newsmst01.news.prodigy.com!prodigy.com!rip!news.webusenet.com!router1.news.adelphia.net!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!postnews1.google.com!not-for-mail From: seunosewa@inaira.com (Seun Osewa) Newsgroups: comp.databases.theory,comp.databases.object,comp.databases Subject: Re: Introducing PlayDB (The Model, The Language, The DBMS) Date: 9 Oct 2003 19:20:48 -0700 Organization: http://groups.google.com Lines: 24 Message-ID: References: NNTP-Posting-Host: 81.18.40.123 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-Trace: posting.google.com 1065752448 19407 127.0.0.1 (10 Oct 2003 02:20:48 GMT) X-Complaints-To: groups-abuse@google.com NNTP-Posting-Date: Fri, 10 Oct 2003 02:20:48 +0000 (UTC) Xref: newssvr20.news.prodigy.com comp.databases.theory:21689 comp.databases.object:16507 comp.databases:48156 Based on my own observations, I would like to define a class as: "A set of Objects/Entities percieved to have certain similar properties." In this definition there is no notion of hierarchy because that's the way it is in real life. A square is a rhombus, a rhombus is a parallelogram. A square is also a rectangle, which is not a rhombus, but is a parallelogram. So we would have difficulty defining one "superclass" for square. Then of course a parallelogram could turn out to be a rhombus on resizing, a rectangle could become auitable to join the group of squares on resizing, etc. And I think this is just the case in real world that the classES an object belongs to can also be dynamic. And when you look at the relational model, well, it requires you to choose a type for each item of data. What if an object could be a member of any arbitrary set of classes? What if this mapping of object to class was totally dynamic? It reminds me of interfaces in Java programming where an object can export an infinite number of interfaces, only that of course all this is dome at compile-time. Things could be come more complicat....err... interesting! Seun Osewa.