Re: Help with Exceptions!

[jsa@organon.com (Jon S Anthony)]

In article <Dr7J1p.18G@world.std.com> bobduff@world.std.com (Robert A Duff) writes:

> In article <JSA.96May10151348@organon.com>,
> Jon S Anthony <jsa@organon.com> wrote:
> >This is a nice trick which allows you to approximate Eiffel style
> >exception capabilities.
> 
> I don't like Eiffel's exception capabilities.  The "retry" feature is
> just a loop implemented with a goto (i.e. "retry" is really a backward
> goto).  I much prefer the Ada style, where you explicitly code a loop
> statement, and put a block-statement-with-exception-handler inside that.

Hmmm, just goes to show how people can differ.  I don't think that
Eiffel exception capabilities are as flexible as Ada's, but you can
make a reasonable argument that that is a "good thing".


> Eiffel has some nice features for asserting things about loops (loop
> invariants, and loop variants -- the latter helps prove that the loop
> terminates in a finite number of steps).  But the retry construct seems
> to by-pass all that -- how does one prove that a retry will ever
> terminate?

In general?  You can't.  It's not magic.

/Jon
-- 
Jon Anthony
Organon Motives, Inc.
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