-- General notion of a change in the design room.


deferred class
	CHANGE

feature

  piece : PUZZLE_COMPONENT is 
  -- All changes involve one or more pieces.
  deferred
  end

  undo is
  -- Undo the current change
  require
    False
  deferred
  end

  redo is
  -- Redo the current change
  require
    False
  deferred
  end

end