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bug in clim:draw-ellipse?


> D) Allow programmer intervention.  I had once proposed that back-ends
> should signal a condition when they encountered an unrenderable case.
> Application programmers could then establish handlers that could draw
> alternative graphics, or punt, or whatever.  If there is no handler,
> the back-end can just do B) or C) above.  This never got implemented,
> but do you think it is a good idea?  How fine-grained should the
> condition space be?  UNIMPLEMENTABLE-GRAPHIC or a separate condition
> for each known rendering/ink failure?

This is what my vote would be for.  I believe that CLIM functionality
should *not* be reduced because some of todays back-ends don't support
some required feature.  Eventually the required functionality will
come to be, and performance IMHO is not as overriding a concern as
many would make it out to be.  I don't like the lowest common
denominator approach as it just throws stuff back at the programmer
who have to implement it anyways because of some box that doesn't
provide the necessary functionality.  We should be striving to provide
more functionality (CLIM is a *beautiful* system in this regards) to
make the programmers job easier and delivering good stuff to the end
losers.

I like the idea of providing an escape mechanism for programmers to
implement their own (necessarily) non-portable extensions.  This makes
things very explicit to the programmer during development (rather than
doing something that is "close" and maybe confusing the programmer
unknowningly).  This is not to say that some "default" behavior
shouldn't be provided, but make the programmer explicitly enable it to
prevent confusion.  I'm not qualified to comment on the granularity,
but it seems that "enough" information must be provided to allow the
programmer to make a dispatch to the correct routine.

> E) Documentation.  Vendors supplying CLIM back-ends should just be
> better about documenting which shapes can't be drawn.  This puts the
> burden on the application programmer to study up on all the platforms
> the application may be delivered into.

Well, selecting (D) does not preclude (E).  Certainly there should be
documentation on the port.  The more the better, and we all know how
much we like writing this stuff :-)

BTW - Would CLIM benefit from optional vendor products such as PHIGS
      for the back-end to take advantage of?  Maybe the lowest level
      doesn't support everything (you get what you pay for) but if you
      really need more functionality, then buy this niffty vendor add
      on and you have it!

ba

Brian H. Anderson                     (206) 234-0881
Boeing Commercial Airplane Co.        bha@gumby.boeing.com
Seattle, Wa.


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