python核心编程 第六章练习6-2

6–2. 字符串标识符.修改例6-1 的idcheck.py 脚本,使之可以检测长度为一的标识符,并且可以识别Python 关键字,对后一个要求,你可以使用keyword 模块(特别是keyword.kelist)来帮你.

import string
from keyword import iskeyword

nums = string.digits
characters = string.letters + '_'

def check(val):
length = len(val)
if length == 0:
print "empty id!"
return
if val[0] not in characters:
print "error! The first character must me '_' or letters "
return
if iskeyword(value):
print "error ! %s is a key word !" % value
return

others = val[1:]
for ch in others:
if ch not in (nums+characters):
print "error character :%s" % ch
return

print 'valid id!'

if __name__=="__main__":
while True:
value = raw_input(">>>\n")
value = value.strip()
if value == "quit":
break
check(value)