python中获取当前位置所在的行号和函数名（转）

http://www.vimer.cn/2010/12/%E5%9C%A8python%E4%B8%AD%E8%8E%B7%E5%8F%96%E5%BD%93%E5%89%8D%E4%BD%8D%E7%BD%AE%E6%89%80%E5%9C%A8%E7%9A%84%E8%A1%8C%E5%8F%B7%E5%92%8C%E5%87%BD%E6%95%B0%E5%90%8D.html

对于python，这几天一直有两个问题在困扰我:

• 1.python中没办法直接取得当前的行号和函数名。这是有人在论坛里提出的问题，底下一群人只是在猜测python为什么不像__file__一样提供__line__和__func__，但是却最终也没有找到解决方案。
• 2.如果一个函数在不知道自己名字的情况下，怎么才能递归调用自己。这是我一个同事问我的，其实也是获取函数名，但是当时也是回答不出来。

但是今晚！所有的问题都有了答案。
一切还要从我用python的logging模块说起，logging中的format中是有如下选项的:

01	%(name)s            Name of the logger (logging channel)

02	%(levelno)s         Numeric logging level for the message (DEBUG, INFO,

03	WARNING, ERROR, CRITICAL)

04	%(levelname)s       Text logging level for the message ("DEBUG", "INFO",

05	"WARNING", "ERROR", "CRITICAL")

06	%(pathname)s        Full pathname of the source file where the logging

07	call was issued (if available)

08	%(filename)s        Filename portion of pathname

09	%(module)s          Module (name portion of filename)

10	%(lineno)d          Source line number where the logging call was issued

11	(if available)

12	%(funcName)s        Function name

13	%(created)f         Time when the LogRecord was created (time.time()

14	return value)

15	%(asctime)s         Textual time when the LogRecord was created

16	%(msecs)d           Millisecond portion of the creation time

17	%(relativeCreated)d Time in milliseconds when the LogRecord was created,

18	relative to the time the logging module was loaded

19	(typically at application startup time)

20	%(thread)d          Thread ID (if available)

21	%(threadName)s      Thread name (if available)

22	%(process)d         Process ID (if available)

23	%(message)s         The result of record.getMessage(), computed just as

24	the record is emitted

也就是说，logging是能够获取到调用者的行号和函数名的，那会不会也可以获取到自己的行号和函数名呢？
我们来看一下源码，主要部分如下:

01	def currentframe():

02	"""Return the frame object for the caller's stack frame."""

03

try:

04	raise Exception

05

except:

06	return sys.exc_info()[2].tb_frame.f_back

07	def findCaller(self):

08

"""

09	Find the stack frame of the caller so that we can note the source

10	file name, line number and function name.

11

"""

12	f = currentframe()

13	#On some versions of IronPython, currentframe() returns None if

14	#IronPython isn't run with -X:Frames.

15	if f is not None:

16	f = f.f_back

17	rv = "(unknown file)", 0, "(unknown function)"

18	while hasattr(f, "f_code"):

19	co = f.f_code

20	filename = os.path.normcase(co.co_filename)

21	if filename == _srcfile:

22	f = f.f_back

23

continue

24	rv = (co.co_filename, f.f_lineno, co.co_name)

25

break

26

return rv

27	def _log(self, level, msg, args, exc_info=None, extra=None):

28

"""

29	Low-level logging routine which creates a LogRecord and then calls

30	all the handlers of this logger to handle the record.

31

"""

32	if _srcfile:

33	#IronPython doesn't track Python frames, so findCaller throws an

34	#exception on some versions of IronPython. We trap it here so that

35	#IronPython can use logging.

36

try:

37	fn, lno, func = self.findCaller()

38	except ValueError:

39	fn, lno, func = "(unknown file)", 0, "(unknown function)"

40

else:

41	fn, lno, func = "(unknown file)", 0, "(unknown function)"

42	if exc_info:

43	if not isinstance(exc_info, tuple):

44	exc_info = sys.exc_info()

45	record = self.makeRecord(self.name, level, fn, lno, msg, args, exc_info, func, extra)

46	self.handle(record)

我简单解释一下，实际上是通过在currentframe函数中抛出一个异常，然后通过向上查找的方式，找到调用的信息。其中

1	rv = (co.co_filename, f.f_lineno, co.co_name)

的三个值分别为文件名，行号，函数名。(可以去http://docs.python.org/library/sys.html来看一下代码中几个系统函数的说明)
OK，如果已经看懂了源码，那获取当前位置的行号和函数名相信也非常清楚了，代码如下:

01	#!/usr/bin/python

02	# -*- coding: utf-8 -*-

03

'''

04	#=============================================================================

05	#  Author:          dantezhu - http://www.vimer.cn

06	#  Email:           zny2008@gmail.com

07	#  FileName:        xf.py

08	#  Description:     获取当前位置的行号和函数名

09	#  Version:         1.0

10	#  LastChange:      2010-12-17 01:19:19

11	#  History:

12	#=============================================================================

13

'''

14	import sys

15	def get_cur_info():

16	"""Return the frame object for the caller's stack frame."""

17

try:

18	raise Exception

19

except:

20	f = sys.exc_info()[2].tb_frame.f_back

21	return (f.f_code.co_name, f.f_lineno)

22

23	def callfunc():

24	print get_cur_info()

25

26

27	if __name__ == '__main__':

28	callfunc()

输入结果是:

1	('callfunc', 24)

符合预期~~
哈哈，OK！现在应该不用再抱怨取不到行号和函数名了吧~

=============================================================================
后来发现，其实也可以有更简单的方法，如下:

1	import sys

2	def get_cur_info():

3	print sys._getframe().f_code.co_name

4	print sys._getframe().f_back.f_code.co_name

5	get_cur_info()

================================================================================

另外,利用python的 inspect 模块中的getframeinfo也可以得到.

inspect.getframeinfo( frame [, context ])

Get information about a frame or traceback object. A 5-tuple is returned, the last five elements of the frame’s frame record.

Changed in version 2.6: Returns a named tuple Traceback(filename, lineno, function,code_context, index).