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From: ncohen@watson.ibm.com (Norman H. Cohen)
Newsgroups: comp.lang.ada
Subject: Re: Array mappings
Date: 13 Dec 1994 15:01:56 GMT
Organization: IBM T.J. Watson Research Center
Distribution: world
Message-ID: <3ckd14$1cqf@watnews1.watson.ibm.com>
References: <9412061309.AA02026@ajpo.sei.cmu.edu>
 <3c4g1u$uh6@watnews1.watson.ibm.com> <3cd4ju$11h@felix.seas.gwu.edu>
Reply-To: ncohen@watson.ibm.com
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Date: 1994-12-13T15:01:56+00:00
List-Id: <comp.lang.ada>

In article <3cd4ju$11h@felix.seas.gwu.edu>, mfeldman@seas.gwu.edu
(Michael Feldman) writes: 

|> This is odd - Ada 93 deliberately leaves array mappings (like all
|> representations) unspecified, so (presumably) as to allow flexibility
|> in the implementations. Was a pragma equivalent to Convention thought
|> to be "feature overkill"?

Ada 83 had an explicit hook for this sort of thing: implementation-
defined representation pragmas.  The philosophy behind Chapter 13 in the
Ada-83 RM was to be as unconstraining as possible, trusting implementors
to "do the right thing" for their platforms.

It eventually became clear that the designers of Ada 83 had been too
trusting, and the ARG started to develop a series of binding
interpretations tightening up the requirements for support of
representation clauses, the one language-defined representation pragma
(Pack), and unchecked conversion.  Some of these interpretations received
final approval from WG9, but consideration of the others was overcome by
events--the promulgation of a full-fledged revised standard addressing
the same issues.

--
Norman H. Cohen    ncohen@watson.ibm.com