I've just seen Daniel Veillard's message about the '_private' field.
In the meantime here is a solution using thread-local storage
implemented on top of pthreads, which may be of interest.
Rich.
--
Richard Jones, Emerging Technologies, Red Hat
http://et.redhat.com/~rjones
Read my OCaml programming blog:
http://camltastic.blogspot.com/
Fedora now supports 59 OCaml packages (the OPEN alternative to F#)
http://cocan.org/getting_started_with_ocaml_on_red_hat_and_fedora