在python中获取当前位置所在的行号和函数名

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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defcurrentframe():

    """Return the frame object for the caller's stackframe."""

    try:

        raiseException

    except:

        returnsys.exc_info()[2].tb_frame.f_back

deffindCaller(self):

    """

    Find the stackframe 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.

    iffisnotNone:

        f=f.f_back

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

    whilehasattr(f,"f_code"):

        co=f.f_code

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

        iffilename==_srcfile:

            f=f.f_back

            continue

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

        break

    returnrv

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()

        exceptValueError:

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

    else:

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

    ifexc_info:

        ifnotisinstance(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

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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:           [e-mail]

#  FileName:        xf.py

#  Description:     获取当前位置的行号和函数名

#  Version:         1.0

#  LastChange:      2010-12-1701:19:19

#  History:        

#=============================================================================

'''

importsys

defget_cur_info():

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

    try:

        raiseException

    except:

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

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

 

defcallfunc():

    printget_cur_info()

 

 

if__name__=='__main__':

    callfunc()

输入结果是:

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('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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importsys

defget_cur_info():

    printsys._getframe().f_code.co_name

    printsys._getframe().f_back.f_code.co_name

get_cur_info()

调用结果是:

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2

get_cur_info

<module>