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From: WhiteR@CRPL.Cedar-Rapids.lib.IA.US (Robert S. White)
Subject: Re: Ada News Brief
Date: 1996/10/28
Message-ID: <551e28$rig@flood.weeg.uiowa.edu>#1/1
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references: <533utt$43p@ns1.sw-eng.falls-church.va.us>
 <Dz96K7.Js6@thomsoft.com> <dewar.845384950@merv> <1996Oct15.160047.1@eisner>
 <32716EA6.4B35@thomsoft.com> <dewar.846422650@merv>
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organization: ranting from home
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 comp.lang.ada,comp.sw.components,comp.object,comp.software-eng,comp.edu
Date: 1996-10-28T00:00:00+00:00
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In article <dewar.846422650@merv>, dewar@merv.cs.nyu.edu says...
...snip...

>1. The switch from an Ada 83 to an Ada 95 compiler may involve changes in
>implementatoin dependent choices (e.g. the behavior of representation 
>pragmas). This is especially likely to be so if you are switching
>front ends (VADS to GNAT, or DEC to Rational, or Alsys to TSP).
>
>2. There are subtle changes in semantics, e.g. of overloading, which are
>unlikely to be copied exactly. It makes no sense to have two overloading
>algorityhms, where the only function of one of them is to implement
>obscure Ada 83 rules that have been judged (a) undesriable and (b)
>too obscure to worry about compatibility issues.
>
>In addition, usually it is only worth trying to worry about correct Ada 83
>rules, there seems little point (and it would be tough) to diagnose all
>possible Ada 83 semantic errors.
>
>One interesting criterion would be to see if a compiler can 100% validate
>against 1.11 with its Ada 83 switch. GNAT certainly makes no such claim.
>

  But as it has been said before, just changing from one Ada 83
implementation to another can show up a lot of similar subtle 
incompatibilities.  Try moving from Tartan Ada 83 to Rational Apex 2.06
Ada 83.   Watch out for operator renames and not enough "use System;"'s.
It seems like I have had fewer problems with Gnat vs other "picky/tough"
Ada 83 compilers.

_______________________________________________________________________
Robert S. White                    -- an embedded sys software engineer
WhiteR@CRPL.Cedar-Rapids.lib.IA.US --long/cheap alternate I-net address
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