Re: 'withing' problem

[Richard Riehle <richard@adaworks.com>]

Simon Wright wrote:

> Well, "arbitrary" translates roughly to "unpredictable", "surprising"
> both of which are definitely bad (I think so, anyway).

Actually, all notation begins, at some point, on the basis of arbitrary
assumptions.   One may construct a system for further reasoning about
those assumptions, but even the foundation for that system is rooted
in arbitrary assumptions.

The UML association shown in an earlier posting illustrates one of the
traps in using UML notation in an incomplete way.   A class diagram
is a static representation of a model.   It is only one way of looking at
the whole model.   One can think of the class diagram as a family portrait
where we can identify the relationships between the members of the
family, but cannot see the dynamics of those relationships.

A more complete model will include the dynamics of those relationships.
As soon as we begin to see the sequence diagrams, activity diagrams, and
collaboration diagrams, we also can determine where we must adjust our
static model.   Grady uses the term, "round-trip gestalt process," to emphasize
the need to continually refine our model based on what we discover in other
views of the model.

As much as it pains me to agree with Matthew Heaney [ :-) ] ,  I have to
do so here.   The circular dependency in the Patient/Doctor design is a
contrivance that fails to reflect A correct design of a medical system. It
is reminiscent of the question, "Can God build a wall so high he cannot
climb over it?"   In the mathematical sense, it is reminiscent of Zeno's
paradox.

Richard Riehle