lib/dm-core/support/assertions.rb
module DataMapper
module Assertions
def assert_kind_of(name, value, *klasses)
klasses.each { |k| return if value.kind_of?(k) }
raise ArgumentError, "+#{name}+ should be #{klasses.map { |k| k.name } * ' or '}, but was #{value.class.name}", caller(2)
end
end
end