Python如何获得函数名和行号？

原文

 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:

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%(name)s Name of the logger (logging channel) %(levelno)s Numeric logging level for the message (DEBUG, INFO, WARNING, ERROR, CRITICAL) %(levelname)s Text logging level for the message ("DEBUG", "INFO", "WARNING", "ERROR", "CRITICAL") %(pathname)s Full pathname of the source file where the logging call was issued (if available) %(filename)s Filename portion of pathname %(module)s Module (name portion of filename) %(lineno)d Source line number where the logging call was issued (if available) %(funcName)s Function name %(created)f Time when the LogRecord was created (time.time() return value) %(asctime)s Textual time when the LogRecord was created %(msecs)d Millisecond portion of the creation time %(relativeCreated)d Time in milliseconds when the LogRecord was created, relative to the time the logging module was loaded (typically at application startup time) %(thread)d Thread ID (if available) %(threadName)s Thread name (if available) %(process)d Process ID (if available) %(message)s The result of record.getMessage(), computed just as 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:

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def currentframe(): """Return the frame object for the caller's stack frame.""" try: raise Exception except: return sys.exc_info()[2].tb_frame.f_back def findCaller(self): """ Find the stack frame of the caller so that we can note the source file name, line number and function name. """ f = currentframe() #On some versions of IronPython, currentframe() returns None if #IronPython isn't run with -X:Frames. if f is not None: f = f.f_back rv = "(unknown file)", 0, "(unknown function)" while hasattr(f, "f_code"): co = f.f_code filename = os.path.normcase(co.co_filename) if filename == _srcfile: f = f.f_back continue rv = (co.co_filename, f.f_lineno, co.co_name) break return rv def _log(self, level, msg, args, exc_info=None, extra=None): """ Low-level logging routine which creates a LogRecord and then calls all the handlers of this logger to handle the record. """ if _srcfile: #IronPython doesn't track Python frames, so findCaller throws an #exception on some versions of IronPython. We trap it here so that #IronPython can use logging. try: fn, lno, func = self.findCaller() except ValueError: fn, lno, func = "(unknown file)", 0, "(unknown function)" else: fn, lno, func = "(unknown file)", 0, "(unknown function)" if exc_info: if not isinstance(exc_info, tuple): exc_info = sys.exc_info() record = self.makeRecord(self.name, level, fn, lno, msg, args, exc_info, func, extra) 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:

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#!/usr/bin/python # -*- coding: utf-8 -*- ''' #============================================================================= # Author: dantezhu - http://www.vimer.cn # Email: [email protected] # FileName: xf.py # Description: 获取当前位置的行号和函数名 # Version: 1.0 # LastChange: 2010-12-17 01:19:19 # History: #============================================================================= ''' import sys def get_cur_info(): """Return the frame object for the caller's stack frame.""" try: raise Exception except: f = sys.exc_info()[2].tb_frame.f_back return (f.f_code.co_name, f.f_lineno)   def callfunc(): print get_cur_info()     if __name__ == '__main__': callfunc()

输入结果是:

('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:

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import sys def get_cur_info(): print sys._getframe().f_code.co_name print sys._getframe().f_back.f_code.co_name get_cur_info()

调用结果是:

get_cur_info
<module>