《Python核心编程（第2版）》读书笔记（6）之用列表模拟堆栈（关键词：Python/列表/堆栈/stack.py）

stack = []

def pushit():
stack.append(raw_input('enter new string: ').strip())

def popit():
if len(stack)==0:
print 'can not pop from an empty stack!'
else:
# 用反单引号（`）来代替repr()函数，把字符串的内容用引号括起来显示，而不是单单显示字符串的内容。
print 'removed [', `stack.pop()`, ']'

def viewstack():
print stack    # calls str() internally

CMDs = {'u': pushit, 'o': popit, 'v': viewstack}

def showmenu():
pr = """
p(U)sh
p(o)p
(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 'uovq':
print 'invalid option, try again'
else:
break

if choice == 'q':
break
CMDs[choice]()

if __name__ == '__main__':
showmenu()