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From: "John G. Volan" <johnvolan@sprintmail.com>
Subject: Re: Software landmines (was: Why C++ is successful)
Date: 1998/09/06
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Date: 1998-09-06T00:00:00+00:00
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Matthew Heaney wrote:
> 
> For example, there's a pernicious myth that exiting (or returning) from
> the middle of a loop is bad, and that the only proper way to write a
> loop is to state the termination condition explicitly, as a predicate
> appearing at the top of the loop.

Maybe the real problem is not where the loop exit occurs _vertically_,
but rather where it occurs _horizontally_ -- that, at what nesting
depth.  Take a look at the thread "Mid-Loop 'Until' Proposal" from
c.l.e.  Consider the comparison I make between a possible Eiffel
extension that would grant a loop more freedom as to where an "until"
clause could be placed, yet still require the terminating postcondition
to appear at the outermost level of nesting; versus Ada's "exit when"
statement, which can reach out and affect the control-flow of its
enclosing loop from some arbitrarily deep level of nesting.

-- 
indexing
   description: "Signatures for John G. Volan"
   self_plug: "Ex Ada guru", "Java 1.1 Certified", "Eiffelist wannabe"
   two_cents: "Java would be even cooler with Eiffel's assertions/DBC, %
              %generics, true MI, feature adaptation, uniform access, %
              %selective export, expanded types, etc., etc..."
class JOHN_VOLAN_SIGNATURE inherit SIGNATURE invariant
   disclaimer: not (opinion implies employer.opinion)
end -- class JOHN_VOLAN_SIGNATURE