indexing
	description: "Objects identified, uniquely during any session, by an integer"

class interface
	IDENTIFIED

feature -- Access

	frozen id_object (an_id: INTEGER): IDENTIFIED
			-- Object associated with an_id (void if no such object)
		ensure
			consistent: Result = void or else Result.object_id = an_id

	frozen object_id: INTEGER
			-- Unique for current object in any given session
		ensure
			valid_id: id_object (Result) = Current
	
feature -- Comparison

	is_equal (other: like Current): BOOLEAN
			-- Is other attached to an object considered
			-- equal to current object?
		require -- from GENERAL
			other_not_void: other /= void
		ensure -- from GENERAL
			symmetric: Result implies other.is_equal (Current);
			consistent: standard_is_equal (other) implies Result
	
feature -- Status report

	frozen id_freed: BOOLEAN
			-- Has Current been removed from the table?
	
feature -- Removal

	frozen free_id
			-- Free the entry associated with object_id if any
		ensure
			object_freed: id_freed
	
feature -- Duplication

	copy (other: like Current)
			-- Update current object using fields of object attached
			-- to other, so as to yield equal objects.
		require -- from GENERAL
			other_not_void: other /= void;
			type_identity: same_type (other)
		ensure -- from GENERAL
			is_equal: is_equal (other)
	
invariant

		-- from GENERAL
	reflexive_equality: standard_is_equal (Current);
	reflexive_conformance: conforms_to (Current);

end -- class IDENTIFIED