From: Nobuyoshi Nakada <nobu@...>
Date: 2011-05-27T08:17:52+09:00
Subject: [ruby-core:36495] Re: [Ruby 1.9 - Feature #4786][Open] RCR new Feature: Numeric#grouped

Hi,

At Fri, 27 May 2011 07:22:37 +0900,
Roger Pack wrote in [ruby-core:36494]:
> Background:
> Currently in ruby you can enter large numbers with digit grouping:
> a = 1_000_000_000
> 
> however there is no convenient way to convert from a number back to digit grouping
> 
> Suggestion:
> 
> >> 1_000_000_000.grouped
> => "1,000,000,000"

If you use round-tripping as the base, the separater should be
"_" by default.

>  class Numeric
>    def separate(sep=",")
>      self.e
>    end
>  end

It makes 12323.separate("xy") "12yx323", which does not seem
nice.

And not all locales use 3-digits separation.

  def separate(n, sep="_")
    to_s.gsub(/\G(?<!\d)(?<=\d{#{n}})(?=\d)|(?<=\d)(?=\d{#{n}}+\b)/, sep)
  end

-- 
Nobu Nakada