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From: Richard Melvin <rmelvin@radm.demon.co.uk>
Subject: Re: Software landmines (loops)
Date: 1998/09/02
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Date: 1998-09-02T00:00:00+00:00
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In article <6silt4$gb0@flatland.dimensional.com>, Jim Cochrane
<jtc@dimensional.com> writes
>
>It appears that this routine has an implied pre-condition:
>l.size() == r.size()
>
snip..
>
>I think, more appropriately, it argues for the "Document routine
>pre/post-conditions (as well as use assertions as documentation of
>program state, where appropriate)" camp.

I hardly think so, given that this was a comparison operator for a stack
- a stack, pretty much by definition, is variable-length (perhaps with a
fixed maximum length, but that's not relevant).

Just throwing in extra preconditions to cover bugs in the implementation
is not my interpretation of design-by-contract.

Otherwise I can revolutionise the world of fast sort algorithms:

void 
sortInLinearTime(Vector & v)
{
        PRE (v.length() < 2);
        return;
}

(assuming PRE is counted as an externally-documented precondition, not
an assertion).
-- 
Richard Melvin