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From: ell@access.digex.net (Ell)
Subject: Re: Software landmines (loops)
Date: 1998/10/09
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Date: 1998-10-09T00:00:00+00:00
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Matthew Heaney <matthew_heaney@acm.org> wrote:

>I don't think Dijkstra is in the business of "authorizing" what
>loop constructs are allowed.  Indeed, as David Gries has pointed out, in
>his monograph, Dijkstra nowhere defines what "structured programming"
>actually means.

In a quote close to an overall view he said that the first thing he
thought of when someone mentioned structured programming was
"abstraction".  ("The Art of Literate Programming",  D. Knuth, CLSC,
page 72)

This tends to back up the point I (and I think Heaney) have made in
previous articles that it seems Dijkstra was emphasizing that
navigation should mainly take place between coherent abstractions as
opposed navigating between free standing entities.

It also makes me think that modelling was a key aspect of the
structured paradigm because the essential act of abstraction, "the act
or process of separating the inherent qualities or properties of
something from the actual physical object or concept to which they
belong" is also the essence of modelling and simulation in software
engineering generally.

Elliott
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