set_allowed_actions

# File actionpack/lib/action_controller/resources.rb, line 137
        def set_allowed_actions
          only    = @options.delete(:only)
          except  = @options.delete(:except)

          if only && except
            raise ArgumentError, 'Please supply either :only or :except, not both.'
          elsif only == :all || except == :none
            options[:actions] = DEFAULT_ACTIONS
          elsif only == :none || except == :all
            options[:actions] = []
          elsif only
            options[:actions] = DEFAULT_ACTIONS & Array(only).map(&:to_sym)
          elsif except
            options[:actions] = DEFAULT_ACTIONS - Array(except).map(&:to_sym)
          else
            # leave options[:actions] alone
          end
        end