From: han.holl@... (Han Holl)
Date: 2004-07-09T19:17:31+09:00
Subject: Re: Proposal for Hash#invert

"Robert Klemme" <bob.news@gmx.net> wrote in message news:<2l58ksF8qv8pU1@uni-berlin.de>...
> 
> A check for block_given? is missing here:
>
No, I don't think so. arbitrate will be empty if there is no block

> 
> class Hash
> 
>   def invert_test(&b)
>     reverse = self.class.new
> 
>     each do |key, val|
>       if b and reverse.has_key? val
>         b.call reverse, val, key
>       else
>         reverse[val] = key
>       end
>     end
> 
>     reverse
>   end
> 
> end

The trouble with this approach is that you get called on each duplicate
value. Sometimes I find I can only decide on the most appropriate
candidate if I've seen them all, but in most cases your implementation would
work as well.

Cheers,

Han Holl