python中获取当前位置所在的行号和函数名(转)

时间：2021-11-15 08:51:22

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).

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