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From: billwolf%hazel.cs.clemson.edu@hubcap.clemson.edu (William Thomas Wolfe, 2847 )
Newsgroups: comp.lang.ada
Subject: Re: Ada portability and conditional compilation
Message-ID: <7473@hubcap.clemson.edu>
Date: 16 Dec 89 18:07:21 GMT
References: <8912160225.AA08090@Herbrand.Inference.Com>
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Reply-To: billwolf%hazel.cs.clemson.edu@hubcap.clemson.edu
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>From sdl@herbrand.Inference.Com (Daniel Lee):
> In this message, I would like to point out which Ada features 
> are not portable and thus subject to conditional compilation.

   The point about some aspects of Ada 83 software being necessarily
   non-portable is well-taken; but the question is: "Should we address
   the problem via conditional compilation, or by some other means of
   ensuring portability?".  

   Robert Munck has pointed out the flagrant abuses of conditional
   compilation and suggested that not having conditional compilation
   would promote better software engineering practice; it would seem
   that there are better ways of facilitating portability, such as 
   secondary standards, upgrading of SYSTEM and other required packages, 
   and so on.  
   
   Is there some fundamental reason why the use of these two mechanisms
   cannot reasonably address portability issues without introducing
   conditional compilation (Feel free to define "reasonably"...), or
   some benefits which might outweigh the high potential for abuse
   and the inability of compilers to perform optimizations on the basis
   of high-level semantics?  If so, maybe a preprocessing mechanism such
   as conditional compilation should be included in the Ada definition;
   otherwise, perhaps preprocessing is best left as an ad hoc response to
   the lengthy revision cycle. 
   
    
   Bill Wolfe, wtwolfe@hubcap.clemson.edu

   (P.S. Thanks to those who pointed out the rationale behind requiring 
         unique field names and the correct semantics of SYSTEM.NAME; now
         does anyone know why SYSTEM.NAME was not called SYSTEM.TARGET?)