RE: Picking the Tools -- Marrying processing models to data model s

["Bullard, Claude L (Len)" <clbullar@ingr.com>]

Struct or object...

We had a long discussion about this in the XML 
Working Group/SIG phase.  Every now and then, 
a review of Horowitz and Sahni is a good read.

"The set of axioms describe the semantics of 
the operations.  The form in which we choose 
to write the axioms is important.  Our goal 
is to write the axioms in a representation 
independent way.  Then, to discuss ways of 
implementing the functions using a conventional 
programming language.

An implementation of a data structure d is a 
mapping from d to a set of other data structures e. 
This mapping specifies how every object of d 
is to represented by the objects of e.  Secondly, 
it requires that every function of d must be 
written using the functions of the implementing 
data structures e.  Thus we say that integers 
are represented by bit strings, boolean is 
represented by zero and one, an array is 
represented by consecutive words in memory.

In current parlance, the triple, DFA, is referred 
to as an abstract data type.  It is called abstract 
precisely because the axioms do no imply a 
form of representation.  Another way of viewing 
the implementation of a data structure is that it is 
the process of refining an abstract data type until 
all of the operations are expressible in terms of 
directly executable functions.  But in the first 
stage, a data structure should be designed so we 
know what it does, but not necessarily how it will 
do it.   This division of tasks called specification 
and implementation is useful because it helps to 
control the complexity of the entire process."

Amen.  The sweetspot of the basics...

Len 
http://www.mp3.com/LenBullard

Ekam sat.h, Vipraah bahudhaa vadanti.
Daamyata. Datta. Dayadhvam.h


-----Original Message-----
From: Jeff Lowery [mailto:jlowery@scenicsoft.com]

> Yes.  Call it
> 
> C.

No, it's better than C, like C incremented, or C honed to a fine edge... 

Hmmm. Back to where we started...