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:

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

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

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                    WARNING, ERROR, CRITICAL)

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

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                    "WARNING", "ERROR", "CRITICAL")

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

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                    call was issued (if available)

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%(filename)s        Filename portion of pathname

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

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

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                    (if available)

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%(funcName)s        Function name

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

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                    return value)

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

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%(msecs)d           Millisecond portion of the creation time

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

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                    relative to the time the logging module was loaded

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                    (typically at application startup time)

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%(thread)d          Thread ID (if available)

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%(threadName)s      Thread name (if available)

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%(process)d         Process ID (if available)

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

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                    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():

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

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    try:

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        raise Exception

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    except:

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

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def findCaller(self):

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    """

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

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    file name, line number and function name.

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    """

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    f = currentframe()

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

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

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    if f is not None:

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        f = f.f_back

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

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    while hasattr(f, "f_code"):

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        co = f.f_code

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

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        if filename == _srcfile:

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            f = f.f_back

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            continue

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

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        break

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    return rv

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

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    """

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

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    all the handlers of this logger to handle the record.

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    """

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    if _srcfile:

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

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

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        #IronPython can use logging.

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        try:

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            fn, lno, func = self.findCaller()

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        except ValueError:

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

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    else:

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

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    if exc_info:

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        if not isinstance(exc_info, tuple):

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            exc_info = sys.exc_info()

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

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    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

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

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'''

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

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

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#  Email:           zny2008@gmail.com

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#  FileName:        xf.py

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#  Description:     获取当前位置的行号和函数名

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#  Version:         1.0

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

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#  History:        

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

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'''

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import sys

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def get_cur_info():

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

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    try:

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        raise Exception

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    except:

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

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

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def callfunc():

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    print get_cur_info()

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26
  
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if __name__ == '__main__':

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    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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import sys

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def get_cur_info():

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    print sys._getframe().f_code.co_name

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

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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).