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Message-ID: <46419449.5090404@lexifi.com>
Date: Wed, 09 May 2007 11:28:41 +0200
From: Jean-Marc EBER <jeanmarc.eber@lexifi.com>
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To: Ocaml Mailing List <caml-list@inria.fr>
Subject: question about the OCaml/C interface
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X-Spam: no; 0.00; lexifi:01 ocaml:01 ocaml:01 camlprim:01 alloc:01 camlreturn:01 allocates:01 camlprim:01 alloc:01 camlreturn:01 jeanmarc:01 eber:01 eber:01 jean-marc:01 jean-marc:01 

Hello to all,

I have a little technical question about the OCaml/C interface:

Is the following code "correct":

CAMLprim value my_func(...)
{
   CAMLlocal2(ret);
   ...
   result = ...
   ret = caml_alloc(5, 0);
   Store_field(ret, 0, caml_copy_double(result));
   ...
   CAMLreturn (ret);
}

or, arguing that [caml_copy_double] allocates and may therfore launch a gc cycle 
that may therefore modify [ret], one must write:

CAMLprim value my_func(...)
{
   ...
   CAMLlocal2(v, ret);
   ...
   result = ...
   ret = caml_alloc(5, 0);
   v = caml_copy_double(result);
   Store_field(ret, 0, v);
   ...
   CAMLreturn (ret);
}

I don't find a clear answer to that question in the documentation.

Jean-Marc Eber