异常消息（Python 2.6） [英] Exception message (Python 2.6)

问题描述

在Python中，如果我打开了一个不存在的二进制文件，程序会出现错误并打印出来：

In Python, if I open a binary file that doesn't exist, the program exits with an error and prints:

Traceback (most recent call last):
  File "C:\Python_tests\Exception_Handling\src\exception_handling.py", 
  line 4, in <module>
  pkl_file = open('monitor.dat', 'rb')
  IOError: [Errno 2] No such file or directory: 'monitor.dat'

我可以使用'try-except'来处理这个问题，例如：

I can handle this with 'try-except', like:

try:
    pkl_file = open('monitor.dat', 'rb')
    monitoring_pickle = pickle.load(pkl_file)
    pkl_file.close()
except Exception:
    print 'No such file or directory'

例外，打印以下行？

File "C:\Python_tests\Exception_Handling\src\exception_handling.py", 
line 11, in <module>
pkl_file = open('monitor.dat', 'rb')

所以程序不会退出。

推荐答案

这将打印例外消息：

except Exception, e:
    print "Couldn't do it: %s" % e

这将显示整个追溯：

import traceback

# ...

except Exception, e:
    traceback.print_exc()

但你可能不想抓住异常。一般来说，你能抓住越窄越好。所以你可能想尝试：

But you might not want to catch Exception. The narrower you can make your catch, the better, generally. So you might want to try:

except IOError, e:

代替。另外关于缩小你的异常处理的问题，如果你只关心丢失的文件，那么把try-except只是打开的：

instead. Also on the subject of narrowing your exception handling, if you are only concerned about missing files, then put the try-except only around the open:

try:
    pkl_file = open('monitor.dat', 'rb')
except IOError, e:
    print 'No such file or directory: %s' % e

monitoring_pickle = pickle.load(pkl_file)
pkl_file.close()

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