Hardcore deep hash

hash.rb

class Hash
  
  define_method '[]_with_try_on', do |*args|
    if args.size == 1 and respond_to?(args.first)
      send(:'[]_with_try_on', args.first)
    else
      args.inject(self.dup){|memo, e|  memo.dup.delete(e) if memo.is_a?(Hash)   }
    end
  end
  
  alias_method_chain :[], :try_on
end

#ruby-1.9.2-head :164 > {}[:a, :b]
# => nil 
#ruby-1.9.2-head :165 > {:a => {:b => "c"}}[:a, :b]
# => "c" 
#ruby-1.9.2-head :166 > {:a => {:b => "c"}}[:a, :b, :c]
# => nil