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OBJECT.TXT
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1992-04-21
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ACTION DESIGNER
OBJECT ORIENTED ANALYSIS
AN EXPERIMENT
As of 3/1/90
Object-Oriented Analysis (OOA), Object-Oriented Design (OOD) and
Object-Oriented Programming (OOP) have gotten a lot of attention
lately. Most of the discussion has centered on programming
languages like C++ and Smalltalk. To say that there is
controversy would hardly describe the battle.
I'd like to fire a slavo of my own: you can't do OOP or OOD if
you can't do OOA. In other words, if we don't know where we
are, how can we know where we are going or how to get there?
Now, you might reply, OOA is easy. Identify the objects making
up the system (any system), define them as abstract data types
and you've done OOA. From there, it is straightforward to
do OOD and OOP. Says who?
We aren't even close to having robust OOA methodologies and tools.
Maybe we shouldn't bother, but my gut tells me that it is
worthwhile to pursue the subject. One of the problems is, we
need some kind of a model as a starting point. It would also
be a good idea if the model had some basis in practical
experience as well as theory.
AD contains an EXPERIMENTAL feature: Action Diagram constructs
for one such model. The model is derived from a recent book:
OBJECT-ORIENTED ANALYSYS
Peter Coad and Edward Yourdon
Yourdon Press, 1990
If you have an interest in the subject, you will want to pick this
one up. The authors claim industrial strength experience in OOA
and present a potentially useful model which they claim has worked
for them.
The OOA process Coad and Yourdon describe involves identifying
objects, structure, and subjects and defining attributes and
services. They also present a diagramming technique that I
don't much care for.
Here is what they say about objects:
"An object is an encapsulation and an abstraction:
an encapsulation of Attributes and exclusive Services
on those Attributes; an abstraction of the problem
space, representing one or more occurances in the
problem space."
Whew. You'll have to read the book to put some flesh on those
bones. But, this is the basis for AD's OOA extension.
You can use the Object menu just like the Action menu to insert
OOA supporting control brackets. There are brackets for Classes
Sub Classes, Attributes and Services. They will allow you to
describe hierarchies of objects and browse them by controlling
the level of detail displayed. Keep in mind that Objects are
synonomous with OOP Classes, Attributes with Variables and
Services with Methods.
I think that, with some refinements, it eventually will be
possible to generate code.
Rather than try to rewrite the book here, why don't you take a
look at what is in AD, try it out, read the book and call me so
we can work through this together. I'll add more to this
discussion as I learn more. Maybe we can get some sort of
thread going on CompuServe.
Please register.
Lou Barnett
MetaLogic Corporation
(805) 529-4498