From: Robert Klemme <shortcutter@...>
Date: 2010-09-21T18:00:52+09:00
Subject: Re: An elegant way...

On Tue, Sep 21, 2010 at 10:38 AM, Brian Candler <b.candler@pobox.com> wrote:

Fred, for the contrast here's my engineering approach.  It may not be
elegant (you decide) but you get modularity and reusability.

First I'd start out with a proper representation.  If your numbers are
a central part of your application you may want to spend a class for
them:

Num = Struct.new :pre, :val do
  def succ
    self.class.new pre, val.succ
  end

  def to_s; "#{pre}#{val}" end
  def inspect; "#{self.class.name}(#{self})" end

  include Comparable
  def <=>(o) to_a <=> o.to_a end
end

def Num(s)
  %r{\A(\D*)(\d+)\z} =~ s or raise "bad arg %p" % s
  Num.new $1, $2.to_i
end

Then we can set up a generic mechanism for this

module Enumerable
  def rangify(&bl)
    bl ||= lambda {|x, y| y ? (x..y) : x}

    res = []
    a = b = nil

    each do |x|
      case
      when a.nil?
        a = b = x
      when x == b.succ
        b = x
      else
        res << bl[a, b]
        a = b = x
      end
    end

    res
  end
end


Full story is here http://gist.github.com/589427

Kind regards

robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/