From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID
	autolearn=no autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,e6dde7d957da14ec
X-Google-Attributes: gid103376,public
From: Sazonov Cyril <cyril@geol.spb.su>
Subject: Re: What's with GNAT?
Date: 1996/12/27
Message-ID: <AA4HwmoyZ4@geol.spb.su>#1/1
X-Deja-AN: 206356326
distribution: all
sender: news@ssrun.arcom.spb.su
organization: RIKC SZRGC
keywords: data conversion
newsgroups: comp.lang.ada
x-return-path: geol!geol.spb.su!cyril@bulldozer.arcom.spb.su
Date: 1996-12-27T00:00:00+00:00
List-Id: <comp.lang.ada>


BwB wrote us:

.................
> the GNAT compiler for the SUN (sorry, I don't know the version--I'm not sure
> they do either!). But the problem seems to come from the conversion of an
> "out" parameter. The GNAT compiler says the statement wil raise
> CONTRAINT_ERROR, and if a program is executed it does indeed raise it. Since
> I am not familiar enough with GNAT, I offered to post this question for them.
..................................
> What are missing about GNAT?
..................................
>      procedure Multiply ( Left, Right : in     Global.Cartesian_Vector;
>                           Result      :    out Global.Cartesian_Vector );
..................................
>
>      procedure Multiply ( Left, Right : in     Global.NED_Vector;
>                           Result      :    out Global.NED_Vector  );
>      begin  -- Multiply
>         Multiply ( Global.Cartesian(Left), Global.Cartesian(Right),
>                    Global.NED_Vector(Result)                         );
> -------------------^^^^^^^^^^^^^^^^^^^^^^^^^
>-------------------- claims it will raise CONSTRAINT_ERROR--and does!
>      end Multiply;

I suppose you are missing about the _language_, but not _GNAT_. It seems me
that the thing is that the reurned result is of Global.Cartesian_Vector type
even though the variable Result is of Global.NED_Vector and the type
conversion is to be done _before_ assignment, perfomed by the result return.
So you are to use an intermediate variable to be able to _get_ the wanted
result and the cjnvert it. For example:

      procedure Multiply ( Left, Right : in     Global.NED_Vector;
                           Result      :    out Global.NED_Vector  );

         INTERIM : Global.Cartesian_Vector;

      begin  -- Multiply
         Multiply ( Global.Cartesian(Left), Global.Cartesian(Right),
                    INTERIM ) ;
         Result := Global.NED_Vector ( INTEGRIM ) ;
      end Multiply;

Happy New Year !

Best wishes from Russia !                             Cyril Sazonov