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From: johnro@microsoft.UUCP (John Rogers)
Newsgroups: comp.lang.ada
Subject: Re: Questions on Ada...
Summary: conditional compilation in Ada
Message-ID: <6233@microsoft.UUCP>
Date: 5 Jul 89 23:42:33 GMT
References: <3034@wpi.wpi.edu>
Distribution: usa
Organization: Microsoft Corp., Redmond WA
List-Id: <comp.lang.ada>

Hi!  There is another, more standard, way of doing conditional compilation
in Ada.  The original article had something like:

#ifdef SOMETHING
    random_C_code;
#endif

In Ada, it's possible to have groups of statements that are never
executed.  For instance:

   procedure Example is
     Something : constant Boolean := True;    -- change and recompile...
   begin
     if (Something) then
       random_Ada_Code;
     end if;
   end Example;

If "Something" is set to False in some other environment, then the
statements ("random_Ada_Code") will never be executed.  The ANSI/MIL-STD
for Ada allows this, and allows compilers to completely optimize out the
code.  This acts as a sort of conditional compilation.

Unfortunately, this isn't a complete solution to the need for
conditional compilation.  There's no way to do this for data declarations,
or "with" clauses, or various other things - just executable statements.

Hope this helps...