> > This works because the "null" token does not *start* with any letter
> > in "true" or "false".  "fnull" would be happily converted to "fnil",
> > but eval catches that luckily.

Well, I missed the changes in the regexp and thus missed your point.

The differences between ruby18 and ruby19 are quite interesting
though. Can somebody with deeper knowledge of ruby19 affirm that the
"copy on write" strategy is still in use?