From: Christopher Dicely <cmdicely@...>
Date: 2008-03-04T11:27:57+09:00
Subject: Re: Question on the Ruby Programming Language Book

On Mon, Mar 3, 2008 at 3:44 PM, James Britt <james.britt@gmail.com> wrote:
> Bharat Ruparel wrote:
>
>  > 1  Why do you have to create enumerated objects this way?  This seems a
>  > long way off from Ruby's philosophy of being succint.  Just to define a
>  > few "object" constants I have to go through this?
>  >
>
>  Well, you can add this method:
>
>
>    def next
>       INSTANCES[ (@n+1) % 4]
>    end
>
>
>  and then do this:
>
>
>    season = Season::Autumn
>    puts season
>    puts season.next
>    puts season.next.next
>


Or, better (in Ruby 1.9) add this instead:
---
class Season

  extend Enumerable

  def self.each
    NAMES.each {|name| yield const_get(name.to_s)}
    self
  end

  # more direct than making it sortable by defining a <=> operator,
  # though you could do that instead.
  def self.sort(&block)
    if block then to_a.sort(&block) else to_a end
  end

end
---
And then try (not really all that useful for seasons, but shows that
you've got the full power of Enumerable at hand):
---
Season.sort {|s1, s2| s1.to_s <=> s2.to_s}.each {|s| puts s.to_s}
Season.sort_by {|season| season.to_s}.each {|s| puts s.to_s}
Season.map {|season| season.to_s}.each {|s| puts s}
---
And finally (the one I like the most):
---
seasons = Season.cycle
puts seasons.next
puts seasons.next
puts seasons.next
.
.
.
---
(You can do the same thing to make the class Season an
Enumerable in Ruby 1.8, but Ruby 1.9's Enumerators
and the Enumerable#cycle method really make this
cool, IMO.)