IT技术博客大学习 共学习 共进步
全部 移动开发 后端 数据库 AI 算法 安全 DevOps 前端 设计 开发者

在python中获取当前位置所在的行号和函数名

Vimer 2010-12-16 21:41:08 累计浏览 4,708 次
本机暂存

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:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
%(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:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
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:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
#!/usr/bin/python
# -*- coding: utf-8 -*-
'''
#=============================================================================
#  Author:          dantezhu - http://www.vimer.cn
#  Email:           zny2008@gmail.com
#  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~

同分类推荐文章

  1. 科技爱好者周刊(第 401 期):如何赚到10亿美元 (2026-06-26 08:05:38)
  2. 如何做决策 - 从 Go 的一个 issue 说起 (2026-06-26 08:00:00)
  3. Seven Player:Windows上播放115网盘视频的增强工具 (2026-06-09 00:06:47)

查看更多 开发者 文章 →

建议继续学习

  1. 用Hyer来进行网站的抓取 (累计阅读 158,251)
  2. 配置Nginx+uwsgi更方便地部署python应用 (累计阅读 107,164)
  3. Fix Bug的五个阶段 (累计阅读 42,973)
  4. 程序员技术练级攻略 (累计阅读 35,471)
  5. python实现自动登录discuz论坛 (累计阅读 32,834)
  6. python编程细节──遍历dict的两种方法比较 (累计阅读 20,371)
  7. 每个程序员都应该学习使用Python或Ruby (累计阅读 17,918)
  8. Chrome和goagent的配置方法,你懂的 (累计阅读 16,843)
  9. 调试工具之GDB (累计阅读 14,829)
  10. 30分钟3300%性能提升――python+memcached网页优化小记 (累计阅读 13,742)