Weeeel...
The truth is, I wrote the idea behind this a while back using String#to_proc to compare the way Ruby (roll your own) and Python (Guido decides) evolve. But considering I have no Python experience, I never published the post.
Then today, for some reason, I was thinking about Open Classes again :-)
(http://news.ycombinator.com/item?id=123071 if you don't know to which I am referring.)