From: Martin <martin.dowie@btopenworld.com>
Subject: Re: Interfacing with C ; an ununsed fields dilemma
Date: Thu, 2 Jul 2009 03:16:14 -0700 (PDT)
Date: 2009-07-02T03:16:14-07:00 [thread overview]
Message-ID: <de77ea5e-47ea-4a94-a736-a8e214d8924c@x17g2000yqd.googlegroups.com> (raw)
In-Reply-To: 4a4c8333$0$32672$9b4e6d93@newsspool2.arcor-online.net
On Jul 2, 10:51 am, Georg Bauhaus <rm.dash-bauh...@futureapps.de>
wrote:
> Hibou57 (Yannick Duchêne) schrieb:
>
>
>
> > Hello to all,
>
> > Once again, a topic about interfacing with C structures.
>
> > A lot of C structure are defined with so called “ unused field
> > reserved for future use ” (oftenly never used in any future). This
> > fields are generally to be initialized to zero, what is required, to
> > unsure it will not be errorneously interpreted by the exogenous part
> > of the application, specially if it is dynamically linked to the
> > application (beceause then, its version or its implementation may be
> > differente and unknown of the application which rely on it).
>
> > And here is the dilemma :
>
> > Using clause representation, it is tempting to simply drop this
> > unuseful unusedfields from the visible part of the declaration (yeah
> > dear friend, lot cleaner, really tempting),
>
> Omitting things might be acceptable in mathematical
> discourse, but actually writing things down helps a
> lot in programming, at least it helps me as a reader,
> not up for solving (inter-)language puzzles.
> You explanation of the record's gap fields is itself a hint
> that these components do need some attention.
> Shouldn't therefore Martin's example be the way to go?
>
> This has been discussed before, topics included
>
> for X use all
> record
> ...
> end record;
>
> pragma Zero_Fill and Unchecked_Conversion (for setting bits to 0);
pragma Zero_Fill sounds interesting...but it isn't standard :-(
Cheers
-- Martin
next prev parent reply other threads:[~2009-07-02 10:16 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-07-02 6:20 Interfacing with C ; an ununsed fields dilemma Hibou57 (Yannick Duchêne)
2009-07-02 9:25 ` Martin
2009-07-02 18:14 ` reserved fields; was " tmoran
2009-07-02 9:45 ` Maciej Sobczak
2009-07-02 12:01 ` Hibou57 (Yannick Duchêne)
2009-07-02 12:09 ` Georg Bauhaus
2009-07-02 13:21 ` Hibou57 (Yannick Duchêne)
2009-07-02 15:50 ` Georg Bauhaus
2009-07-02 14:52 ` Maciej Sobczak
2009-07-02 23:21 ` Hibou57 (Yannick Duchêne)
2009-07-03 7:21 ` Maciej Sobczak
2009-07-02 9:51 ` Georg Bauhaus
2009-07-02 10:16 ` Martin [this message]
2009-07-02 11:48 ` Hibou57 (Yannick Duchêne)
2009-07-02 15:55 ` Robert A Duff
2009-07-04 0:03 ` Randy Brukardt
2009-07-03 6:59 ` anon
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