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Message-Id: <4550159.UZ0Ap4ka2d@linux1.krischik.com>
From: Martin Krischik <martin@krischik.com>
Subject: Re: [OT] Re: Teaching new tricks to an old dog (C++ -->Ada)
Newsgroups: comp.lang.ada,comp.lang.c++,comp.realtime,comp.software-eng
Reply-To: martin@krischik.com
Date: Sun, 13 Mar 2005 09:43:10 +0100
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Xref: g2news1.google.com comp.lang.ada:9295 comp.lang.c++:45393
 comp.realtime:1410 comp.software-eng:4975
Date: 2005-03-13T09:43:10+01:00
List-Id: <comp.lang.ada>

Ed Falis wrote:

> On Sat, 12 Mar 2005 12:46:11 -0500, CTips <ctips@bestweb.net> wrote:
> 
>> For example, look at the Ada equivalent of the following code.
>>    typedef enum {0, 1, 2, 3} four_val;
>>    four_val x;
>>     x = (four_val) some_int;
>>    ....
>>    assert( x < 4);
> 
> 
>     type Four_Val is range 0 .. 3;
>     X : Four_Val;

pragma Volatile (X); -- ;-)

> begin
>     X := Four_Val (Some_Int);
>     ...
>     pragma Assert (X < 4, "Something is seriously honked here");
>     --  Currently supported by GNAT; part of Ada 2005
>     --  Or write your own subprogram in Ada 95 as I did for AUnit
>     Do_Something_With (X);

Are you sure? After all 4 is not a valid value for Four_Val. I would rather
go for either:

pragma Assert (X <= Four_Val'Last, "Something is seriously honked here");

or:

pragma Assert (X'Valid, "Something is seriously honked here");
 
> Sounds to me as though you just like to argue, because this one was pretty
> silly.

Of course it is silly - mostly because the C example isn't using volatile
which you should if you fear hardware intervention - otherwise X might be
cached inside a register and you never notice the problem anyway.

Martin
-- 
mailto://krischik@users.sourceforge.net
Ada programming at: http://ada.krischik.com