Re: OO foundation
Date: Wed, 5 Mar 2008 08:13:57 -0800 (PST)
H. S. Lahman wrote:
> Responding to Nobis...
> >> First, I think it is important to clarify that the 'relational' in
> >> the mismatch isn't referring to the fact that the OO paradigm uses
> >> something other than set theory's relational model. The nature of
> >> the impedance mismatch lies in the way the OO and RDB paradigms
> >> implement the same relational model.
> > Huh? I know of the lambda calculus as a foundation of functional
> > languages and the relation model as foundation of RDBs. But I wonder
> > what the formal foundations of the OO family of languages is
> > (references, please).
> The foundation is much broader because of the need to provide dynamic
> elements (i.e., the relational model is a subset of the OO foundation).
This "subset" thing is perhaps misleading. While trying to figure out how to merge paradigms in another forum in order to make everybody happy and stop the bickering, we eventually generally agreed that paradigms are more about *constraints* than features. What a paradigm *doesn't* allow is often more important to defining it than what it does allow. The "no side-effects" rule of Functional Programming is an example. If one tries to create a language or tool that allows multiple paradigms, it often has to relax such constraints such that the essence of the original paradigm is lost.
One cannot "reason" about the results as easily because they don't know which rules a given thing will abide by. Paradigms are tools to help human reasoning by providing rules for the "atoms" to follow. If there are too many rules, or a lack of rules, then it becomes a big ball of twine too hard to get one's head around because any assumption you rely on to mentally narrow down the possible paths something can take may just be all wrong.
> However, the point in this context is that a UML Class Diagram *is* an
> Entity Relationship Diagram and it is normalized exactly the same way as
> an ERD Data Model. But the Class Diagram is just one view of the overall
> solution and it needs to play with other views so the semantics of
> construction are somewhat different, as I indicated in my post.
> There is nothing wrong with me that could
> not be cured by a capful of Drano.
> H. S. Lahman
-T- Received on Wed Mar 05 2008 - 17:13:57 CET