#!/usr/bin/python
# coding=GBK
import re
# 对m作适当处理后返回结果
def fun(m):
  print("in: %s" %m.group(0))
  ret = m.group(0).upper()[::-1]
  return ret
src = "what [can] I do for can you[can] come on"
pat = "(?<=
)(can)(?=
)"
#print(re.search(pat, src).group(1))
#result = re.sub(pat,lambda m:m.group(1).upper()[::-1], src)
# 使用lambda
result1 = re.sub(pat, lambda m:m.group(0).upper()[::-1], src)
print("result1: %s\n" %result1)
# 在re.sub中使用函数
result2 = re.sub(pat, fun, src)
print("result2: %s" %result2)

[zcm@python #112]$./del.py
result1: what [NAC] I do for can you[NAC] come on
in: can
in: can
result2: what [NAC] I do for can you[NAC] come on
[zcm@python #113]$