🚀 go-pugleaf

Dear Scott,

One way to accomplish the "require" and "ensure" attributes of Eiffel objects in
SIMULA is to declare a prefix class, let us call it CLASS protoPostal, with the
the inner attributes "require" and "ensure" declared as procedures.
Arguements to the procedures would define the conditions that are to be
required and insured. Using protoPostal as a prefix to subclasses, for example

protoPostal CLASS postal;

will cause the class postal to inherit the attributes "require" and
"ensure" from protoPostal. These attributes can then be used
independently by all objects from the class postal which are generated
in the model domain. Aside from the work of doing it yourself, which
some might consider a disadvantage, it provides the user with the power
and fexibility to write simple or advanced procedures for "require" and "ensure"
.

Cheers ... Henry Islo

P.S. If you do a careful study and compare SIMULA and Eiffel and actually try to
use the two on real problems, you will eventually and most likely want to
become a member of the SIMULA Users Association. In which case you may request a
registration form from me.

As your studies deepen into the intricacies of SIMULA and Eiffel you
may eventually come to one of the very central issues of object oriented
programming, i.e. Quasi-Parallel Systems. In fact I think you will find that
Eiffel in many respects is the apprentice that has only learned some of
master SIMULA's skills.