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To: damien.doligez@inria.fr
Cc: caml-list@inria.fr
Subject: Re: [Caml-list] Unix.file_descr -> int ???
In-Reply-To: <20020612185729P.garrigue@kurims.kyoto-u.ac.jp>
References: <200206120953.LAA0000032113@beaune.inria.fr>
	<20020612185729P.garrigue@kurims.kyoto-u.ac.jp>
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Message-Id: <20020612200402C.garrigue@kurims.kyoto-u.ac.jp>
Date: Wed, 12 Jun 2002 20:04:02 +0900
From: Jacques Garrigue <garrigue@kurims.kyoto-u.ac.jp>
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From: Jacques Garrigue <garrigue@kurims.kyoto-u.ac.jp>
> From: Damien Doligez <damien.doligez@inria.fr>
> > >Windows version:
> > >
> > >let dump_handle (h : Unix.file_descr) =
> > >  let obj = Obj.repr h in
> > >  if Obj.is_block obj && Obj.tag obj = Obj.custom_tag then
> > >    Nativeint.format "%x" (Obj.obj obj)
> > >  else invalid_arg "dump_handle"
> > 
> > This does not work.  You are printing the address of the custom block
> > that contains the handle, but this address can change during program
> > execution.
> 
> Indeed, this is buggy. But you could have given the right answer :-)

What are you making me write!
This code was correct. I have been using it for months in ocamlbrowser
for windows.
nativeint itself is a boxed custom datatype, so outputing it will
correctly output the handle, not the pointer to it. I'm just using the
fact they share the same representation. Actually file_descr has
another field, but we don't need it.

Jacques Garrigue
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