Python的traceback模块

traceback模块被用来跟踪异常返回信息. 如下例所示:

import traceback
try:
    raise SyntaxError, "traceback test"
except:
    traceback.print_exc()

将会在控制台输出类似结果:

Traceback (most recent call last):

File "H:\PythonWorkSpace\Test\src\TracebackTest.py", line 3, in

raise SyntaxError, "traceback test"

SyntaxError: traceback test

 

 

类似在你没有捕获异常时候, 解释器所返回的结果.
你也可以传入一个文件, 把返回信息写到文件中去, 如下:

import traceback
import StringIO
try:
    raise SyntaxError, "traceback test"
except:
    fp = StringIO.StringIO() #创建内存文件对象
    traceback.print_exc(file=fp)
    message = fp.getvalue()
    print message

这样在控制台输出的结果和上面例子一样
traceback模块还提供了extract_tb函数来格式化跟踪返回信息, 得到包含错误信息的列表, 如下:

import traceback
import sys

def tracebacktest():
    raise SyntaxError, "traceback test"
try:
    tracebacktest()
except:
    info = sys.exc_info()
    for file, lineno, function, text in traceback.extract_tb(info[2]):
        print file, "line:", lineno, "in", function
        print text
    print "** %s: %s" % info[:2]

 

控制台输出结果如下:

H:\PythonWorkSpace\Test\src\TracebackTest.py line: 7 in

tracebacktest()

H:\PythonWorkSpace\Test\src\TracebackTest.py line: 5 in tracebacktest

raise SyntaxError, "traceback test"

** : traceback test

 

Example 2-18 展示了 traceback 模块允许你在程序里打印异常的跟踪返回 (Traceback)信息, 类似未捕获异常时解释器所做的. 如 Example 2-18 所示. 2.11.0.1. Example 2-18. 使用 traceback 模块打印跟踪返回信息 File: traceback-example-1.py # note! import
Example 2-18 展示了 traceback 模块允许你在程序里打印异常的跟踪返回 (Traceback)信息, 类似未捕获异常时解释器所做的. 如 Example 2-18 所示.

2.11.0.1. Example 2-18. 使用 traceback 模块打印跟踪返回信息

 

File: traceback-example-1.py

# importing the traceback module messes up the
# exception state, so you better do that here and not
# in the exception handler
# 导入 traceback 会清理掉异常状态, 所以
# 最好别在异常处理代码中导入该模块
import traceback

try:
    raise SyntaxError, "example"
except:
    traceback.print_exc()

 

Traceback (innermost last):

File "traceback-example-1.py", line 7, in ?

SyntaxError: example

 

Example 2-19 使用 StringIO 模块将跟踪返回信息放在字符串中.

2.11.0.2. Example 2-19. 使用 traceback 模块将跟踪返回信息复制到字符串
File: traceback-example-2.py

 

import traceback
import StringIO

try:
    raise IOError, "an i/o error occurred"
except:
    fp = StringIO.StringIO()
    traceback.print_exc(file=fp)
    message = fp.getvalue()

    print "failure! the error was:", repr(message)

 

failure! the error was: 'Traceback (innermost last):\012 File

"traceback-example-2.py", line 5, in ?\012IOError: an i/o error

occurred\012'

 

你可以使用 extract_tb 函数格式化跟踪返回信息, 得到包含错误信息的列表, 如 Example 2-20 所示.

2.11.0.3. Example 2-20. 使用 traceback Module 模块编码 Traceback 对象
File: traceback-example-3.py

 

import traceback
import sys

def function():
    raise IOError, "an i/o error occurred"

try:
    function()
except:
    info = sys.exc_info()
    for file, lineno, function, text in traceback.extract_tb(info[2]):
        print file, "line", lineno, "in", function
        print "=>", repr(text)
    print "** %s: %s" % info[:2]

 

traceback-example-3.py line 8 in ?

=> 'function()'

traceback-example-3.py line 5 in function

=> 'raise IOError, "an i/o error occurred"'

** exceptions.IOError: an i/o error occurred

 

文章来自 http://docs.python.org/dev/library/traceback.html