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Re: CLIM question
John,
I have been working with CLIM-2.0.alpha and just getting familiar with some
of the basic properties of CLIM geometry. I don't know how much of what I am
discovering is merely an artifact of the alpha version and how much is there
by design. But my feeling is that there is an apparent effort to minimize the
sophistication of the geometry model. My concern is that the geometry model
will have very limited utility for spacial modeling and necessitate the
development of entirely parallel geometry models to do anything non-trivial
in a mathematical sense.
For example, I was dissappointed to find that region-intersection does not
currently provide a means of determining if two line-segments intersect,
but only if they overlap, due to the dimensionality rule. This of course
is also a problem for intersections of areas or areas and lines, etc.
Similarly, region-union seems to provide identical (eq) results for polylines
in union with polygons, at least in the test case I ran.
I have also had problems with the containment test generic function, not
having methods defined for all possible combinations of regions. But I
suspect that is merely an alpha artifact.
I think it would be nice if rectangular polygons could be coerced to
rectangles at creation, since they are immutable and could logically be
considered a subclass of polygon so that the test rectanglep would work
on arbitrary rectangular regions and the rectangles would not be bereft
of the polygon protocols such as map-over-polygon-segments or map-over-
polygon-coordinates.
Reading the beginning of section 3.2 Other Region Types in the 2.0.alpha
documentation (from Franz) indicates that there is some sort of proposal
to even further diminish the utility of regions by removing polygons, poly-
lines, ellipses, and elliptical arcs. I certainly would like to hear the
rationale for this; I think it would be a serious flaw and is a move in
the wrong direction.
Please give me a little background on the current philosophy of CLIM
development as it pertains to these concerns and to any other areas that
may still be in a state of flux. I could go on and on, but this is enough
to get a discussion going.
--------
Cordially,
Gregory M. Whittaker, The MITRE Corporation
Center for Advanced Aviation
System Development
Internet: greg@mitre.org 7525 Colshire Drive
Phone: (703) 883-5549 McLean Virginia 22102-3481
FAX: (703) 883-1226 Mail Stop: W215
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