note
	description: "Observer objects used in Eiffel Query Language"
	legal: "See notice at end of class."
	status: "See notice at end of class."
	author: ""
	date: "$Date$"
	revision: "$Revision$"

deferred class
	QL_OBSERVER

feature -- Notification

	update (a_observable: QL_OBSERVABLE; a_data: ANY)
			-- Notification from `a_observable' indicating that `a_data' changed.
		deferred
		end

feature -- Actions

	actions: ACTION_SEQUENCE [TUPLE]
			-- Actions to be performed every time after `update' is been called.
		do
			if internal_actions = Void then
				create internal_actions
			end
			Result := internal_actions
		ensure
			result_attached: Result /= Void
		end

feature{NONE} -- Implementation

	internal_actions: like actions
			-- Implementation of `actions'.

invariant
	actions_attached: actions /= Void

note
	copyright: "Copyright (c) 1984-2013, Eiffel Software"
	license: "GPL version 2 (see http://www.eiffel.com/licensing/gpl.txt)"
	licensing_options: "http://www.eiffel.com/licensing"
	copying: "[
			This file is part of Eiffel Software's Eiffel Development Environment.
			
			Eiffel Software's Eiffel Development Environment is free
			software; you can redistribute it and/or modify it under
			the terms of the GNU General Public License as published
			by the Free Software Foundation, version 2 of the License
			(available at the URL listed under "license" above).
			
			Eiffel Software's Eiffel Development Environment is
			distributed in the hope that it will be useful, but
			WITHOUT ANY WARRANTY; without even the implied warranty
			of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
			See the GNU General Public License for more details.
			
			You should have received a copy of the GNU General Public
			License along with Eiffel Software's Eiffel Development
			Environment; if not, write to the Free Software Foundation,
			Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
		]"
	source: "[
			Eiffel Software
			5949 Hollister Ave., Goleta, CA 93117 USA
			Telephone 805-685-1006, Fax 805-685-6869
			Website http://www.eiffel.com
			Customer support http://support.eiffel.com
		]"



end