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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Interesting article on ARG work
Date: Sat, 7 Apr 2018 12:11:31 +0200
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Xref: reader02.eternal-september.org comp.lang.ada:51376
Date: 2018-04-07T12:11:31+02:00
List-Id: <comp.lang.ada>

On 2018-04-07 04:25, Randy Brukardt wrote:

> The biggest problem with a lexical solution (and the reason that Ichbiah
> hated them) is that it's trivial to accidentally create a program that is
> only legal in one mode or the other. One has to continually compile
> everything in each possible mode to ensure that there aren't silly syntax
> errors involved. A common mistake that I make all of the time is:
> 
>      if Foo then
>             Bar;
>      else
> @        Internal_Error;
>      end if;
> 
> With the conditional compilation off, the "Internal_Error" is commented out
> and the above isn't syntactically legal.

Yes, this is important but I think this could be resolved, e.g. by 
compiling conditionals into corresponding null-effect constructs.

> Ichbiah wanted to eliminate that
> from Ada, so there's no Include (a common feature of other languages back in
> the day, and heavily used in the very early versions of Janus/Ada, long gone
> now), no preprocessor, and so on -- everything is handled within the usual
> syntax of the language. Which doesn't always work that well...

Though dangers of preprocessing outweigh any inconvenience.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de