Difference between *options and options

ruby-talk
1

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

···

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2

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