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From: "David C. Hoos, Sr." <david.c.hoos.sr@ada95.com>
Subject: Re: LLQ: -1 a valid boolean?
Date: 2000/05/23
Message-ID: <8gebvj$20i$1@hobbes2.crc.com>#1/1
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References: <39253CD0.C8DC893D@telepath.com> <8g8o3b$9l0$1@nnrp1.deja.com>
 <8ge39b$g45$1@nnrp1.deja.com>
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Newsgroups: comp.lang.ada
Date: 2000-05-23T16:34:59+00:00
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return To_Bool_Ptr(Addr).all;

might look a little less "silly" than

   if To_Bool_Ptr(Addr).all then
      return True;
   else
      return False;
   end if;

Ted Dennison <dennison@telepath.com> wrote in message
news:8ge39b$g45$1@nnrp1.deja.com...
> In article <8g8o3b$9l0$1@nnrp1.deja.com>,
>   Robert Dewar <robert_dewar@my-deja.com> wrote:
> > In article <39253CD0.C8DC893D@telepath.com>,
> >   Ted Dennison <dennison@telepath.com> wrote:
> > > You'd think that a value that is legal in situ ought to be
> > > legal to assign as well. Then again, if Ada_Boolean'Size = 8
> > > or 32 or something, then I can see where one might argue that
> > > a value of -1 (all bits set) is out of range of the possible
> > > Boolean values, and thus should raise
> > > Constraint_Error.
> > >
> > > So what's right?
> >
> > Not only is the compiler's behavior conforming, it is actually
> > what one would expect, given that you most certainly expect
> > that boolean objects have a size of 8 (the choice of a size
> > of 1 for boolean objects is typically impractical on most
> > architectures due to the task indepedence requirement).
> >
> > Your code is just wrong here, and you are going to have to
> > deal with these booleans in a completely different manner.
>
> That's what I was afraid of.
>
> > If your compiler implements Interfaces.Fortran, then everything
> > should be fine, since the type Logical should work properly.
>
> Except that sometimes the value comes from a Fortran program, and
> sometimes it comes from a C program.
>
> I just ended up doing the following, which looks damn silly (so I had
> to comment it copiously), but works:
>
>    if To_Bool_Ptr(Addr).all then
>       return True;
>    else
>       return False;
>    end if;
>
> --
> T.E.D.
>
> http://www.telepath.com/~dennison/Ted/TED.html
>
>
> Sent via Deja.com http://www.deja.com/
> Before you buy.