Hi group.

Please have a look at the following:

irb(main):001:0>  class F < Struct.new :n
irb(main):002:1>    def dec_n
irb(main):003:2>      n = n - 1
irb(main):004:2>    end
irb(main):005:1>  end
=>  nil
irb(main):006:0>  f = F.new 1
=>  #<struct F n=1>
irb(main):007:0>  f.dec_n
NoMethodError: undefined method `-' for nil:NilClass
        from (irb):3:in `dec_n'
        from (irb):7
        from :0
irb(main):008:0> 

I've tried to define a class which decrease n by 1, but failed. How can
I do that?

- Minkoo Seo