# File lib/active_resource/base.rb, line 361
      def prefix=(value = '/')
        # Replace :placeholders with '#{embedded options[:lookups]}'
        prefix_call = value.gsub(/:\w+/) { |key| "\#{options[#{key}]}" }

        # Clear prefix parameters in case they have been cached
        @prefix_parameters = nil

        # Redefine the new methods.
        code = "def prefix_source() \"\#{value}\" end\ndef prefix(options={}) \"\#{prefix_call}\" end\n"
        silence_warnings { instance_eval code, __FILE__, __LINE__ }
      rescue
        logger.error "Couldn't set prefix: #{$!}\n  #{code}"
        raise
      end