Thanks to all for the info on this. It sounds like with strings I won't get any
advantage from COW at all on slicing, and that even with arrays I'll not be much
better off.

For my current purposes, I don't see how to use arrays anyway, since I'm
interested primarily in large chunks of contiguous memory.

Any pointers relating to what I'm doing in my Extended Set Theory articles will
be gratefully received. A ping via email will help, as I don't get back here as
frequently as I probably should.

Thanks,

-- 
Ron Jeffries
www.XProgramming.com
I'm giving the best advice I have. You get to decide if it's true for you.