Caml-list mailing list. Subscription management:
Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
Bug reports: http://caml.inria.fr/bin/caml-bugs
Hope this helps,
De : caml-lis...@yquem.inria.fr [mailto:caml-lis...@yquem.inria.fr] De la part de micha
Envoyé : mardi 26 décembre 2006 19:16
À : OCaml Mailing List
Objet : [Caml-list] allocating memory for c-structures
Ce message et toutes les pieces jointes (ci-apres le "message") sont confidentiels et etablis a l'intention exclusive de ses destinataires.
Toute utilisation ou diffusion non autorisee est interdite.
Tout message electronique est susceptible d'alteration.
Societe Generale Asset Management et ses filiales declinent toute responsabilite au titre de ce message s'il a ete altere, deforme ou falsifie.
Decouvrez l'offre et les services de Societe Generale Asset Management sur le site www.sgam.fr
This message and any attachments (the "message") are confidential and intended solely for the addressees.
Any unauthorised use or dissemination is prohibited.
E-mails are susceptible to alteration.
Neither Societe Generale Asset Management nor any of its subsidiaries or affiliates shall be liable for the message if altered, changed or falsified.
Find out more about Societe Generale Asset Management's proposal on www.sgam.com
That seems like it'll work for "opaque" C objects, but it's a bit of a
hack. The immediate issues I can think are:
(a) Pointers in the C code which point at the object will not be
"counted" by the GC, and so the object may be collected while there
are still C pointers around. This is easily avoided in OCaml, but
read chapter 18 of the manual carefully.
(b) By storing the object as a string you're telling the GC not to
examine the inside of the object, eg. looking for pointers inside to
other objects. Fine, if you know what you're doing, but OCaml already
has a number of established ways to do this - eg. using Abstract or
Custom blocks - and these standard ways are not just standard, but
offer additional features too. Alternatively you may consider a
non-abstract block and deliberately allow the GC to look inside. C
and OCaml structures are not actually too different.
Actually, while I was writing the above, it struck me that perhaps
you're talking about some sort of marshalling system? OCaml supports
its own marshalling format, and a rich variety of other external forms
Richard Jones, CTO Merjis Ltd.
Merjis - web marketing and technology - http://merjis.com
Internet Marketing and AdWords courses - http://merjis.com/courses - NEW!
Merjis blog - http://blog.merjis.com - NEW!
I don't believe Ocaml guarantees the contents of a string
will remain in a fixed location .. it might move the storage
to a new address .. so pointers into the structure might
John Skaller <skaller at users dot sf dot net>
Felix, successor to C++: http://felix.sf.net
Richard Jones schrieb:
> That seems like it'll work for "opaque" C objects, but it's a bit of a
> hack. The immediate issues I can think are:
> (a) Pointers in the C code which point at the object will not be
> "counted" by the GC, and so the object may be collected while there
> are still C pointers around. This is easily avoided in OCaml, but
> read chapter 18 of the manual carefully.
that's true; for linked data structures it would not work (except all
would be allocated this way)
> Actually, while I was writing the above, it struck me that perhaps
> you're talking about some sort of marshalling system? OCaml supports
> its own marshalling format, and a rich variety of other external forms
> of marshalling.
ah no, I just thought that it would be another way to handle external
What I didn't realize was, that the gc moves pointers around...