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From: johnherro@aol.com (John Herro)
Subject: Re: Backward compatibility between Ada 95 and Ada 83
Date: 1997/09/30
Message-ID: <19970930121201.IAA12959@ladder02.news.aol.com>#1/1
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Newsgroups: comp.lang.ada
Date: 1997-09-30T00:00:00+00:00
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"James H. Robinson, III" <jr3uva90@erols.com> writes:
> I'm using an Ada 95 compiler, but my
> class is teaching Ada 83.  How backwardly
> compatible is Ada 95 with is Ada 83?

Very.  You have almost nothing to worry about.  With very few exceptions,
Ada 95 is a superset of Ada 83, and anything you write in Ada 83 will
compile in Ada 95.

Of course, you must avoid using the six new reserved words as identifiers:
abstract, aliased, protected, requeue, tagged, and until.  One other thing
*might* bite you:  Let's say you write an Ada 83 package spec that requires
no body (because it contains only type definitions and object declarations,
but no procedure and function specs).  Now let's say you want to write a
body anyway, perhaps to initialize an array.  This will compile in Ada 83,
but in Ada 95 it won't compile until you add pragma Elaborate_Body.  Remove
that pragma when you turn in your Ada 83 assignment.  If you don't
understand that because you haven't covered packages yet, don't worry about it!

Good luck in your class!  I know you'll really like Ada!

- John Herro
Software Innovations Technology
http://members.aol.com/AdaTutor
ftp://members.aol.com/AdaTutor