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From: "Daniel Bünzli" <daniel.buenzli@epfl.ch>
To: matthieu.dubuget@laposte.net
Cc: caml-list@inria.fr
Subject: Re: [Caml-list] CAMLreturn does not work for floats between 0 and 1 ?
Date: Fri, 16 Feb 2007 18:07:32 +0100	[thread overview]
Message-ID: <16855695-F439-47FB-80D1-171CD88833C2@epfl.ch> (raw)
In-Reply-To: <45D5D9DC.8050704@laposte.net>


Le 16 févr. 07 à 17:20, Matthieu Dubuget a écrit :

> Suppose that I have to construct one or more value(s) to pass them to
> OCaml land. I do have to use CAMLlocal macros for that, don't I.

It depends. If you _allocate_ (e.g. ints are not allocated) a caml  
value \x13v1 then another caml v2 and then modify v1, you need to keep a  
hand on v1 with CAMLparam because it may move when you allocate v2.  
If you allocate only a single value then there is no need to do it  
(unless some code you call may invoke the gc before you use v1).

> Can use them without CAMLparam and CAMLreturn macros?

No. But I never did the C -> ocaml -> C way so I don't really know  
how to proceed. The first thing that comes to mind is to store the  
result in a variable given to  the function.

void f1 (int i, double *result) {
	CAMLparam...
	*result = ...
	CAMLreturn0;
}

Maybe there's another way, I don't know.

Daniel


  parent reply	other threads:[~2007-02-16 17:05 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-16 14:46 Matthieu Dubuget
2007-02-16 15:09 ` [Caml-list] " Daniel Bünzli
2007-02-16 16:20   ` Matthieu Dubuget
2007-02-16 17:02     ` Mathias Kende
2007-02-16 17:07     ` Daniel Bünzli [this message]
2007-02-16 19:19       ` Matthieu Dubuget
2007-02-16 22:28         ` Daniel Bünzli
2007-02-17  0:30 ` Jacques Garrigue

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