def initialize(options = {})
if !options.empty? && !(options.keys - [:only, :except]).empty?
raise ArgumentError, "The only valid options are :only and :except. You specified #{options.keys.join(',')}."
end
if options.has_key?(:only) && options.has_key?(:except)
raise ArgumentError, "You may only specify either :only or :either. Doing both doesn't really make sense does it?"
end
@only = options[:only]
@tables_to_exclude = (options[:except] || [])
if migration_storage = migration_storage_name
@tables_to_exclude << migration_storage
end
end