On 28 Mar 2003 at 18:14, Tim Bates wrote:

> What might be useful is for join to take a block which decides 
> what separator to use based on the value of the previous item, eg:
>   (1..10).to_a.join { |i|
>     i % 2 == 0 ? " " : "-"
>   } # => "1-2 3-4 5-6 7-8 9-10"
> This is a trivial example, and I can't think of a real example off the top of 
> my head, so feel free to reject it on the grounds that it may not be useful, 
> but this just occurred to me and I thought I'd throw it out there...

I don't have any use for this yet, too, but you could even pass both 
the last and the next item to the block.

Regards,
Pit