dm-1 associated records external tree walker

tree_walker.rb

class TreeWalker
  def initialize(customer, &block)
    @customer, @block = customer, blocj
  end

  def emit(resource)
    @block.call(resource)
  end

  def customer(customer)
    customer.users.each do |user|
      emit(user)
      user(user)
    end
  end

  def user(user)
    user.stuff.each do |stuff|
      emit(stuff)
      stuff(stuff)
    end
  end

  def run
    customer(customer)
  end

  def self.run(customer, &block)
    new(customer, &block).run
    self
  end
end

Use with:

TreeWalker.run(customer) do |record|
  do_stuff_with(record)
end