Re: [CoFI] Revised proposal for CASL Views, Imports

[Joseph Goguen <goguen@cs.ucsd.edu>]

In regard to "implicit fitting views", I would like to make three simple
observations:

1. In my opinion, the issue of semantic correctness cannot be used as an
argument against implicit views, because exactly the same argument
applies to
all views: they are syntactic ("static") entities that should be checked
for
semantic correctness before they are used.

2. The fact that achieving a fully general solution is difficult is not
a
valid argument against this feature, because it is possible to implement
something very simple that is still extremely useful, as demonstrated by
the
OBJ3 implementation, first described in my paper "Parameterized
programming"
and later in more detail in the OBJ3 manual.

3. Countless users have found (what OBJ3 calls) default views to be
extremely
useful; in many cases the improvement in writability and readability is
very
dramatic.  It is not a valid argument to say that a default view can
always be
replaced by the name of an explicit view that is defined elsewhere,
because
there is still the effort of writing that view, or in the case of a
specification reader, of not only understanding the view, but also of
finding
it in the code.  Finding the significant parts of a large view that
mainly
consists of obvious mappings can be tedious.

-- Joseph

******************************************************************************
Joseph Goguen, Dept. Computer Science & Engineering, University of
  California at San Diego, 9500 Gilman Drive, La Jolla CA 92093-0114 USA
  email: goguen@cs.ucsd.edu
  www:   http://www.cs.ucsd.edu/users/goguen/
  phone: (619) 534-4197 [my office]; -1246 [dept office]; -7029 [dept
fax]; 
         (619) 822-0702 [secy: Lisa Bodecker]
  office: 3131 Applied Physics and Math Building
  J Consciousness Studies: http://www.zynet.co.uk/imprint/