tree class of Ruby

class Tree
  include Enumerable
  
  attr_accessor :left, :right
  
  def initialize(str)
    @str = str
  end
  
  def each
    left.each {|t| yield t } if left
    right.each{|t| yield t } if right
    yield @str
  end
  
end

t1 = Tree.new('a')
t1.left = Tree.new('a_left')
t1.right = Tree.new('a_right')
t1.left.left = Tree.new('a_left_left')
t1.right.left = Tree.new('a_right_left')
t1.right.right = Tree.new('a_right_right')

t1.each {|t| puts t}

# >> a_left_left
# >> a_left
# >> a_right_left
# >> a_right_right
# >> a_right
# >> a