module Osheet::StyledElement def style_class(value); @style_class = verify_style_class(value); end private def verify_style_class(style_class) if !style_class.kind_of?(::String) || invalid_style_class?(style_class) raise ArgumentError, "invalid style_class: '#{style_class}', cannot contain '.' or '>'" else style_class end end def invalid_style_class?(style_class) style_class =~ /\.+/ || style_class =~ />+/ end end