From: Mats Weber <Mats.Weber@elca-matrix.ch>
Subject: Re: win32ada design question/problem
Date: 1998/11/17
Date: 1998-11-17T00:00:00+00:00 [thread overview]
Message-ID: <36519A6A.C07508F5@elca-matrix.ch> (raw)
In-Reply-To: 72s2as$pbg$1@nnrp1.dejanews.com
dennison@telepath.com wrote:
>
> In article <ubtm7cxj0.fsf@gsfc.nasa.gov>,
> Stephen Leake <Stephen.Leake@gsfc.nasa.gov> wrote:
> >
> > While I agree it wasn't well designed, I don't agree you need to go to
> > a thick binding. The binding should use 'out' parameter modes in the
> > places where C uses pointers to achieve output parameters. Most
> > compilers will map an 'out' parameter to a C pointer, since that's
> > what 'by reference' means.
>
> Actually, according to B.3(68), that is *required* behavour. The problem with
> that technique is that many C routines attach a signifigance to a incomming
> value of null. You won't be able to produce such a value on the Ada side, so
> some of the functionality of the C routine will be lost.
And there is another, more severe problem. The C function may allocate
some memory that you must free later, e.g.
procedure P (X : out Some_Record_Type);
pragma Import(C, P);
now as you have no pointer to the returned data, you cannot free it.
I think the Ada 83 classic int + System.Address approach is better in
this case.
next prev parent reply other threads:[~1998-11-17 0:00 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
1998-11-13 0:00 win32ada design question/problem Mats Weber
1998-11-13 0:00 ` Tom Moran
1998-11-16 0:00 ` Mats Weber
1998-11-18 0:00 ` Tom Moran
1998-11-18 0:00 ` dennison
1998-11-19 0:00 ` Mats Weber
1998-11-19 0:00 ` Mats Weber
1998-11-19 0:00 ` dennison
1998-11-19 0:00 ` David Botton
1998-11-19 0:00 ` David Botton
1998-11-19 0:00 ` Mats Weber
1998-11-23 0:00 ` Marin David Condic
1998-11-27 0:00 ` Roga Danar
1998-11-13 0:00 ` dennison
1998-11-16 0:00 ` Stephen Leake
1998-11-16 0:00 ` Tucker Taft
1998-11-17 0:00 ` dennison
1998-11-17 0:00 ` Mats Weber [this message]
1998-11-17 0:00 ` dennison
1998-11-17 0:00 ` Tucker Taft
1998-11-18 0:00 ` Tom Moran
1998-11-18 0:00 ` dennison
1998-11-17 0:00 ` Mats Weber
-- strict thread matches above, loose matches on Subject: below --
1998-11-19 0:00 tmoran
1998-11-19 0:00 ` dennison
1998-11-19 0:00 ` Tom Moran
1998-11-20 0:00 ` dennison
1998-11-20 0:00 ` Tom Moran
1998-11-23 0:00 ` Marin David Condic
1998-11-23 0:00 ` Mats Weber
1998-11-24 0:00 ` dennison
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