# # This file contains the Ruby code from Program 6.12 of # "Data Structures and Algorithms # with Object-Oriented Design Patterns in Ruby" # by Bruno R. Preiss. # # Copyright (c) 2004 by Bruno R. Preiss, P.Eng. All rights reserved. # # http://www.brpreiss.com/books/opus8/programs/pgm06_12.txt # class Queue < Container def initialize super end abstractmethod :enqueue abstractmethod :dequeue abstractmethod :head end