[self-interest] Model View Controller and the Observer pattern

Albertina Lourenci lourenci at lsi.usp.br
Mon Aug 27 22:43:03 UTC 2001

Jecel Assumpcao Jr wrote:

> Morphic is based on the "one object, one view" philosophy. If you want
> multiple views (a chart and a spreadsheet on the same set of numbers)
> then it won't work for you. That is not true of Morphic in a subjective
> language like Us, however.

OK!But you told me that nobody knows how to implement layers
and views in an efficient way. The way these are implemented
in Sina (from the Mehmet Aksit group) through composition filters and
in C++ , views and layers cannot be expressed explicitly in the object
model but are implemented as pieces of method code and messages
between objects. It is difficult to follow the traceability of the
model with respect to the design model. A unit in the design model
does not have a corresponding unit in the implementation model.The
implementation models the real world problem less exact than possible.
Then those that want to build  software systems whose levels exhibit
isomorphic behaviour are rather interested in developing architectures
that are faithful to the domain model.
And of course design pattern oriented architectures fulfill the promise
for more expressiveness. Especially because a designer can invent
as many patterns as he/she wishes to reflect his/her intentions.

Even if there were a successful implementation of Us, one cannot
forget about the architectural level. The trend of treating  relations
as components or first-order entities seems well expressed in
the agent based approach. However I do not know in which language
they are implementing these ideas.

Best wishes

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