用Python实现队列

#!/usr/bin/env pythonqueue = []def enQ():    queue.append(raw_input('Enter new string: ').strip())#调用list的列表的pop()函数.pop(0)为列表的第一个元素def deQ():    if len(queue) == 0:        print 'Cannot pop from an empty queue!'    else:        print 'Removed [', queue.pop(0) ,']'def viewQ():    print queueCMDs = {'e': enQ, 'd': deQ, 'v': viewQ}def showmenu():    pr = """    (E)nqueue    (D)equeue    (V)iew    (Q)uit        Enter choice: """    while True:        while True:            try:                choice = raw_input(pr).strip()[0].lower()            except (EOFError, KeyboardInterrupt, IndexError):                choice = 'q'            print '\nYou picked: [%s]' % choice            if choice not in 'devq':                print 'Invalid option, try again'            else:                break        if choice == 'q':            break        CMDs[choice]()if __name__ == '__main__':    showmenu()