In message "Re: Method Dispatch (was Adding methods to String, but only in my own Module?)"
    on Fri, 26 Jan 2007 09:17:02 +0900, Yukihiro Matsumoto <matz / ruby-lang.org> writes:

|Keiju Ishitsuka, who named Ruby 14 years ago, once developed a library
|named scope-in-state that did similar work in thread safe manner.  The
|problem is it has been lost for long time (no longer registered in
|RAA).  I will ask him to put it somewhere.  I hope he still has.

It's available from

 http://www.rubyist.net/~keiju/src/scope-in-state.tgz

Note that it's unmodified old code, so that no one know it works for
the current Ruby.  You may need to tweak on it.

							matz.