From: ludo@gnu.org (Ludovic Courtès)
To: guile-user@gnu.org
Subject: Re: Passing C pointers through guile
Date: Wed, 09 Jul 2008 21:54:59 +0200 [thread overview]
Message-ID: <87tzeyx27g.fsf@gnu.org> (raw)
In-Reply-To: Pine.LNX.4.58.0807091850550.3461@notam02.uio.no
Hi,
"Kjetil S. Matheussen" <k.s.matheussen@notam02.no> writes:
> On Wed, 9 Jul 2008, Greg Troxel wrote:
>> Does C guarantee that pointers fit in unsigned long?
>
> I don't know. But in practice: Yes.
That's usually the case but it's not guaranteed, which is why C99
provides `uintptr_t' in <stdint.h>.
> Sure, if you just do this now and then, SMOBs aren't a problem.
> But that doesn't change the fact that all the functionality SMOB
> provides is overkill when the only thing you need is to hold
> a pointer.
It's not overkill, it's exactly what you need: disjoint SMOB type,
`free' and `mark' procedures.
> For those who needs the full functionality of SMOB's, or need
> the extra speed and memory advantages of SMOB's, they are free
> to use SMOB's. If not, the functions scm_to/from_uintptr
> can be used instead, which is a billion times easier to use.
Not really: as mentioned on `guile-devel', you'll need to implement that
functionality (disjoint type, garbage collection) on top of your
integer. One advantage is that this can be done in Scheme (except for
the `mark' procedure, but it's not always needed); the main drawback in
the context of Guile is poor performance.
Thanks,
Ludovic.
next prev parent reply other threads:[~2008-07-09 19:54 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <cmu-lmtpd-16223-1215360367-2@mail-imap1.uio.no>
2008-07-06 16:13 ` Passing C pointers through guile Kjetil S. Matheussen
2008-07-06 19:20 ` Ludovic Courtès
2008-07-09 16:48 ` Greg Troxel
2008-07-09 16:55 ` Kjetil S. Matheussen
2008-07-09 19:54 ` Ludovic Courtès [this message]
2008-07-10 15:11 ` Ken Raeburn
2008-07-23 11:19 ` Greg Troxel
2008-07-10 12:54 Kjetil S. Matheussen
-- strict thread matches above, loose matches on Subject: below --
2008-07-04 22:18 Maciek Godek
2008-07-05 16:59 ` Ludovic Courtès
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