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From: "Nicolas Cannasse" <warplayer@free.fr>
To: "Xavier Leroy" <xavier.leroy@inria.fr>
Cc: "kyra" <kyrab@mail.ru>, "OCaml" <caml-list@inria.fr>
References: <000901c237fe$04a92510$0700a8c0@warp> <001901c239b4$be8ccbf0$551aa8c0@kyra> <001101c23a0d$2f184220$0700a8c0@warp> <000d01c23ae3$9dd62700$551aa8c0@kyra> <003b01c23c54$32324570$0700a8c0@warp> <20020805113255.C7554@pauillac.inria.fr>
Subject: Re: [Caml-list] OCam'OLE pre-release
Date: Mon, 5 Aug 2002 11:51:08 +0200
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> > The job of the GC is to release unreferenced objects.
> > But I don't see how this can cause a bug : it seems that your crash is
due
> > to a call of a COM method on a object AFTER it has been released... if
it
> > has been Release, then it is no longer referenced by Ocaml... so , how
can u
> > ever call a method on it ???
>
> Because the COM object can still be referenced from C.  You probably
> forgot to do an AddRef somewhere, e.g. when extracting a COM object
> reference from its Caml wrapper.
>
> Reference count management sure is tricky...

True.
If you're using OCamole to manipulate COM objects and then passing them back
to C, your C code need to call AddRef on the retreived COM object since
OCamole GC'ed process does not respect the COM spec (caller is responsible
from Release, callee call AddRef )

Simply use the following function :

IUnknown *get_com_object( value v ) {
    IUnknown *o = IUnknown_val(v);
    o->AddRef();
    return o;
}

Nicolas Cannasse

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