新手学Python 外篇一 队列的实现

queue = []
def enQ():
queue.append(raw_input('Enter new string:').strip())

def deQ():
if len(queue) == 0:
print 'Cannot pop from an empty queue!'
else:
print 'Removed[',queue.pop(0),']'
def viewQ():
print queue

CMDs ={'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 '\n You 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()