class Haml::Buffer

def parse_object_ref(ref)

just like you can do with `dom_id()` and `dom_class()` in Rails
The second object, if present, is used as a prefix,
one to create an attributes hash.
Takes an array of objects and uses the class and id of the first 
def parse_object_ref(ref)
  prefix = ref[1]
  ref = ref[0]
  # Let's make sure the value isn't nil. If it is, return the default Hash.
  return {} if ref.nil?
  class_name =
    if ref.respond_to?(:haml_object_ref)
      ref.haml_object_ref
    else
      underscore(ref.class)
    end
  ref_id =
    if ref.respond_to?(:to_key)
      key = ref.to_key
      key.join('_') unless key.nil?
    else
      ref.id
    end
  id = "#{class_name}_#{ref_id || 'new'}"
  if prefix
    class_name = "#{ prefix }_#{ class_name}"
    id = "#{ prefix }_#{ id }"
  end
  { 'id'.freeze => id, 'class'.freeze => class_name }
end