加载模块时python捕获NameError [英] python catching NameError when loading module

问题描述

我正在尝试捕获无法加载模块时发生的所有异常. 当前结果是未执行"except"块.

I'm trying to catch any exceptions that happen when you cannot load a module. The current results are that the "except" block does not get executed.

import sys 
def loadModule(module):
   try: 
      import module
   except: 
      print """ 
      Cannot load %s
      For this script you will need: 
         cx_Oracle:  http://cx-oracle.sourceforge.net/
         pycrypto:   https://www.dlitz.net/software/pycrypto/
         paramiko:   http://www.lag.net/paramiko/
       """ % module
      sys.exit(1)

loadModule(cx_Oracle)

错误:

Traceback (most recent call last):
  File "./temp_script.py", line 16, in <module>
    loadModule(cx_Oracle)
NameError: name 'cx_Oracle' is not defined

推荐答案

loadModule(cx_Oracle)

您认为您要将此功能传递给什么?到目前为止，代码中没有任何名为cx_Oracle的东西.这就是为什么您收到NameError的原因.您甚至都没有进入该功能.

What do you think you are passing to this function? There is nothing named cx_Oracle in the code so far. That's why you are getting a NameError. You aren't even getting into the function.

 import module

您不能传递要导入的变量，它会将您输入的内容解释为模块的文字名称

You can't pass variables to import, it interprets what you put in as the literal name of the module

在这种情况下，我质疑您甚至需要一个功能.只需将try/except移到模块级别，然后直接导入cx_Oracle.

In this case, I question that you even need a function. Just move the try/except to the module level and import cx_Oracle directly.

仅因为我很好奇，这是一种使您可以创建可重用的异常捕获导入函数的方法.我不确定何时/如何使用它，但是这里是:

Just because I was curious, here is a way you can make a reusable exception-catching import function. I'm not sure when/how it would be useful, but here it is:

from contextlib import contextmanager
import sys

@contextmanager
def safe_import(name):
    try:
        yield
    except:
        print 'Failed to import ' + name
        sys.exit(1)

with safe_import('cuckoo'):
    import cuckoo

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