python中使用sys模板和logging模块获取行号和函数名的方法
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2023-11-03 21:38:04
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_...
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()
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
<module>
<module>
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