Re: use eiffel to build a CAM library?

["Thomas G. McWilliams" <tgm@netcom.com>]

Paul Johnson <Paul@treetop.demon.co.uk> wrote:
: OO designs don't use callbacks in the C way: you should use inheritance
: and polymorphism instead.  These play similar tricks with function
: pointers behind the scenes, but you don't need to worry about that.

I disagree. If one's OO design operates purely in a synthetic domain,
then callbacks may not be needed. But the real world is composed of
data representations that must be cajoled into a format acceptable
to OO techniques. Callbacks are most useful when attempting to parse
non-OO streams in an OO fashion. Callbacks can be dispatched on some
discriminant retrieved from the stream, rather than using ugly "if-then",
"inspect", or "case" type techniques. The weakness of all OO languages
seems to be the lack of a general high-level way to describe the mapping of
non-OO stream data into objects. Ada is better than most in this respect,
but it is still has a long way to go.