[GOODIE] BinaryRelation

Richard A. O'Keefe ok at cs.otago.ac.nz
Mon Mar 31 21:39:09 UTC 2003


Avi wrote:
	Come on, I'm not "bemoaning" anything, nor do I think the "only" is
	necessary.  As I said, an algebra of binary relations is a natural
	approach for what you're doing, but it's rather awkward to model a set of
	Oracle tables that way (or at least, it seems so in my ignorance - feel
	free to enlighten me).

I want to point out that the purpose of my BinaryRelation class is
*NOT* to model a set of Oracle tables but simply to plug a gap in
the data structures available to *programmers* for in-memory programming.
Over many years I have learned to think of relations as a valuable tool
for my own programming and design *without* any reference to relational
databases as such.

(BinaryRelation now includes #converse, #reachableFromSource[s]:,
#reachableFromTarget[s]:, and #* .)

E. F. Codd has published a list of 12 criteria for what makes something
a relational database.  (At the time, SQL did _not_ qualify...)  Amongst
other things, persistence, audit/recovery, and authorisation control are
important.  These things must be dealt with in any Smalltalk modelling
of Oracle tables.  They are completely irrelevant to a set of pairs
data structure for internal programming use.



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