From: Sebastian Hungerecker <sepp2k@...>
Date: 2007-09-21T04:14:15+09:00
Subject: Re: Idiomatic Ruby for Array#extract / Range#length?

Xavier Noria wrote:
> So, in what sense succ is not required?

You can have a range of objects that don't have succ. You just can't iterate 
over that range. You can check whether a given object is inside that range 
though. See:

class Bla
  attr_accessor :blabb
  @@blubb=0

  def initialize()
    @blabb=@@blubb
    @@blubb+=1
  end

  def <=>(other)
    blabb<=>other.blabb
  end
end

arr=Array.new(10) {Bla.new}

(arr[2]..arr[5]).include? arr[4] #=> true
(arr[2]..arr[5]).include? arr[1] #=> false
(arr[2]..arr[5]).include? arr[7] #=> false

(arr[2]..arr[5]).each do end # TypeError: can't iterate from Bla


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