From: Justin Collins <justincollins@...>
Date: 2009-01-07T14:51:25+09:00
Subject: Re: difference between *options and options

Sijo Kg wrote:
> Hi
>    I saw below code
>
> options = { :a => 1, :b => 2, :c => 3 }
> rejects = Hash[*options.select { |k, v| k == :b && options.delete(k)
> }.flatten]
>
>    In the above if I use options insted of *options what is actually
> happening..I would like to know their difference What actually means
> *options
>
> Thanks in advance
> Sijo
>   

This code might be a little deceptive, but if you look closely 
"options.select { |k, v| k == :b && options.delete(k)}.flatten" is just 
creating an array out of selected keys and values. After that, the splat 
operator (*) is being used to turn the array into parameters for the 
Hash.[] function...which turns it back into a hash. Tada!

I note that in Ruby 1.9.1, Hash#select returns a hash, making this 
weirdness unnecessary.

More about splat, including this particular use: 
http://advent2008.hackruby.com/past/2008/12/12/meet_the_splat/

-Justin