Re: Interfacing with C: access/out parameters

["Egil H. H�vik" <egil.harald.hoevik@REMOVEkongsberg.com>]

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"Egil H. H�vik" <egil.harald.hoevik@REMOVEkongsberg.com> wrote in message
news:41342a34@193.71.169.73...
>
> "Jano" <notelacreas@porfavor.no> wrote in message
> news:2ph6fjFkpsahU1@uni-berlin.de...
> > Hi,
> <snip>
> >
> > function Blah (Datum : access Data) return C.Int;
> > pragma Import (C, Blah);
> >
> >
> > Procedure Ada_Blah (Datum : out Data);
> > -- May raise some exception
> >
> > And my doubt, finally, is: can I ensure somehow that Datum is passed by
> > reference?, so I can do inside Ada_Blah [1]:
> >
> > Helper : aliased Datum;
> > For Helper'Address use Datum'Address;
> > if Thin_Package.Blah (Helper'Access) = Error_Value then
> >     raise My_Error;
> > end if;
> >
>
> Well, you say Data is a record type, so what's wrong with:
>
> procedure Ada_Blah( Datum : out Data ) is
>    function Blah( Datum : Data ) return C.int;
>    pragma Import( C, Blah );
> begin
>    if Thin_Package.Blah(Datum) = Error_Value then

hmm... Copy-Paste error here... Should be Blah(Datum), minus Thin_Package


>       raise My_Error;
>    end if;
> end Ada_Blah;
>
>
> B.3(65): "An Ada function corresponds to a non-void C function"
> B.3(69): "An Ada parameter of a record type T, of any mode, is passed as a
> t* argument
>    to a C function, where t is the C type corresponding to the Ada type
T."
>
>
> ~egilhh
>
>