deferred class interface P_DISPENSER[G] feature(s) from P_CONTAINER -- Status count: INTEGER -- Number of items in the container. ensure positive: Result >= 0 is_empty: BOOLEAN -- Is the container empty? is_readable: BOOLEAN -- Is the container currently readable? is_writable: BOOLEAN -- Is the container currently writable? item: G -- Current item. require readable: is_readable; not_empty: not is_empty feature(s) from P_CONTAINER -- Update reset -- Remove all objects from the container. require writable: is_writable ensure done: is_empty feature(s) from P_CONTAINER -- Output out: STRING -- String representation. ensure is_copy: -- new string feature(s) from P_CONTAINER -- Utility is_void (x: ANY): BOOLEAN -- Void assertion for generic parameters. feature(s) from P_DISPENSER -- Update add (it: G) -- Add an item to the dispenser (push). ensure keep_reference: -- keep a copy of the item. remove -- Remove an item from the dispenser and update -- the current item (pop). require meaningful: not is_empty feature(s) from P_DISPENSER -- Conversion to_list: P_LIST[G] -- Convert the dispenser to a list. ensure valid_result: Result /= Void; -- new list but old items. is_shallow_copy: invariant empty: is_empty = count = 0; end of deferred P_DISPENSER[G]