Re: Mut. Recurs. in Ada9X w/o Breaking Encaps.? (LONG)

[mbk@inls1.ucsd.edu (Matt Kennel)]

John Volan (jgv@swl.msd.ray.com) wrote:
: I guess the real philosophical issue that everything is hinging on
: here is: "Is a binary association *part* of the abstraction of each of
: the classes, or is it a *separate* abstraction of its own?"

: Adam Beneschan objected to other solutions that put the association
: structure in a common root package, on the grounds that nothing from
: the "real world" was being modeled by that.  I disagree with that, and
: agree with Magnus Kempe that in fact the association should be treated
: as a first-class abstraction of its own, in some fashion.

I think it's somewhat more than just a 'philosophical' issue.

If you have a "thing" managing the mutual couplings, you can
easily guarantee that

 employee(office(this_employee_object)) = this_employee_object.
 (and the reverse).

i.e. that you always maintain an invertible one-to-one relation.

I thought this was one of the original requirements.

If you have a 'thing' relating the two, you can put this
guarantee logic in one place, instead of having this fact be
implicitly relying upon the proper programming of the classes
to be related.

--
-Matt Kennel  		mbk@inls1.ucsd.edu
-Institute for Nonlinear Science, University of California, San Diego
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