associations_create_has_many_reflection.rb

  mattr_accessor :valid_keys_for_has_many_association
  @@valid_keys_for_has_many_association = [
    :class_name, :table_name, :foreign_key, :primary_key,
    :dependent,
    :select, :conditions, :include, :order, :group, :having, :limit, :offset,
    :as, :through, :source, :source_type,
    :uniq,
    :finder_sql, :counter_sql,
    :before_add, :after_add, :before_remove, :after_remove,
    :extend, :readonly,
    :validate, :inverse_of
  ]

  def create_has_many_reflection(association_id, options, &extension)
    options.assert_valid_keys(valid_keys_for_has_many_association)
    options[:extend] = create_extension_modules(association_id, extension, options[:extend])

    create_reflection(:has_many, association_id, options, self)
  end