def user(user, &block)
      logger.debug "Got user: #{user}"

      @data[:user], @data[:host] = user.to_s.split '@'
      @data[:host] ||= '%'

      instance_eval(&block) if block_given?
    end
def user(user, &block)
      logger.debug "Got user: #{user}"

      @data[:user], @data[:host] = user.to_s.split '@'
      @data[:host] ||= '%'

      instance_eval(&block) if block_given?
    end
Define user and host
 Note: revokes all permissions for given user first