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From: Roy Phillips <roy.phillips@trcinc.com>
Subject: Re: OO, C++, and something much better!
Date: 1997/01/10
Message-ID: <32D64F6C.37D3@trcinc.com>#1/1
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references: <5b1ais$oev@wdl1.wdl.lmco.com> <E3rGKv.7Gx@syd.csa.com.au>
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 comp.lang.c++,comp.lang.smalltalk,comp.lang.eiffel,comp.lang.ada,comp.object,comp.software-eng
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Date: 1997-01-10T00:00:00+00:00
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Don Harrison wrote:
> Mark A Biggar writes:
> 
> :Of course there is nothing that requires
> :that the provided function realy be a less-than function (which is usefull
> :as providing a ">" instead reverses the order of the list) but Eiffel has the
> :same problem and there is no guarentee that a class derived from COMPARABLE
> :hasn't redefined "<" to do something else either.
> 
> While it wouldn't be possible in this case, a level of confidence can be
> provided in other situations using Eiffel postconditions.

   The problem with this approach is not really the deliberate
substitution
of the ">" with a "<": as stated, this can be a useful technique (I'd
hate
to have to maintain that code, all the same!).  More problematical is
the
accidental substitution, for example of an operation with same name but
an
entirely differant meaning (for example, the terms 'interest' (financial
domain) and 'interest' (marketing domain)) - blame the English language
if
you will, but without semantic specification (i.e., Eiffel assertions)
the
whole thing is a can of worms.

- Roy