My TSort Example

gistfile1.rb

require 'tsort'
require 'pp'

Node = Struct.new :value, :before, :after

class Collection < Array
  include TSort

  alias :tsort_each_node :each
  def tsort_each_child(current, &block)
    select { |competitor| 
      current.after == competitor.value || # Is there any node be run after the current node?
      competitor.before == current.value # Is there any node run before the current node?
    }.each(&block)
  end
end

collection = Collection.new
collection << Node.new(1, 2, 4)
collection << Node.new(2)
collection << Node.new(3, 4)
collection << Node.new(4, 1, 3)

pp collection.strongly_connected_components
# [[#<struct Node value=3, before=4, after=nil>],
#  [#<struct Node value=4, before=1, after=3>],
#  [#<struct Node value=1, before=2, after=4>],
#  [#<struct Node value=2, before=nil, after=nil>]]

This code is to test initializer tsort in rails 3 initialization process