From: Robert Klemme <bob.news@...>
Date: 2005-05-30T16:25:21+09:00
Subject: Re: Coercion and ranges

Philipp Kern wrote:
> Jim Weirich wrote:
>> I find it a bit odd that adding two ranges  results in an array, but
>> assuming that is /really/ what you want, you could indicate a Range's
>> willingness to be converted to an array by including a to_ary method.
>
> Well if I see the range as an array of its elements (which you would
> get when you iterate over it), then it's what one might want. Thank
> you, that solved it. I thought about to_ary yesterday night, but I
> was not aware that it would be called by Array#+.

Another probably more efficient variant would be to create a special class
that represents sums (= sequences) of Enumerables:

class EnumSequence
  include Enumerable

  def initialize(*enums) @enums = enums end

  def each(&b)
    @enums.each {|e| e.each(&b)}
    self
  end

  def +(enum)
     @enums << enum
     self
  end
end

class Range
  def +(r) EnumSequence.new(self,r) end
end

>> x = (1..10) + (100..101) + (23..25)
=> #<EnumSequence:0x100c3d48 @enums=[1..10, 100..101, 23..25]>
>> x.to_a
=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 100, 101, 23, 24, 25]

Kind regards

    robert