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From: Ludovic Brenta <ludovic@ludovic-brenta.org>
Newsgroups: comp.lang.ada
Subject: Re: How do I write directly to a memory address?
Date: Tue, 8 Feb 2011 02:43:56 -0800 (PST)
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Date: 2011-02-08T02:43:56-08:00
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Georg Bauhaus wrote on comp.lang.ada:
> On 2/8/11 11:16 AM, Ludovic Brenta wrote:
>>> Strict contracts in subprogram profiles. Ha!
>
>>> void foo2(int jump)
>>> =A0 =A0 /* make sure jump % 2 =3D=3D 0! */
>>> {
>>> =A0 =A0 =A0...
>>> }
>
>>> Write that in Ada 2005 to demonstrate the glorious power of
>>> your subtype constraints. =A0When was it that compilers will
>>> support aspects reliably?
>
>> Easy:
>
>> procedure Foo2 (Jump : in Natural);
>> -- Jumps by 2 * Jump
>
> > Thereby eliminating the very *possibility* that 2*jump can be odd!
>
> See how you couldn't provide a solution, but made up
> a different case?

No, I provided a proper contract that reflects the problem at hand
rather than your fragile solution.

 =A0 Now
>
> =A0 =A0Foo2 (Jump =3D> Natural'Last);

procedure Foo2 (Jump : in Natural) is
begin
   if Jump <=3D Natural'Last / 2 then
      Baz (2 * Jump);
   else
      declare
         Half_Jump : constant Natural :=3D Jump / 2;
         Remainder : constant Natural :=3D Jump mod 2;
      begin
         Baz (2 * Half_Hump);
         Baz (2 * Half_Jump);
         if Remainder /=3D 0 then
            Baz (2 * Remainder);
         end if;
      end;
   end if;
end Foo2;

And that's assuming Long_Long_Integer is not wide enough for the
calculations.

--
Ludovic Brenta.