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:

复制代码 代码如下:

%(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:

复制代码 代码如下:

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

复制代码 代码如下:

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:

复制代码 代码如下:

!/usr/bin/python

-- coding: utf-8 --

'''

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

FileName: xf.py

Description: 获取当前位置的行号和函数名

Version: 1.0

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

'''
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:

复制代码 代码如下:

('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:

复制代码 代码如下:

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:

复制代码 代码如下:

get_cur_info