python 在python中从NameError获取未定义的名称
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Getting the name which is not defined from NameError in python
提问by Manuel Aráoz
As you know, if we simply do:
如您所知，如果我们只是这样做：
>>> a > 0
Traceback (most recent call last):
File "<pyshell#1>", line 1, in <module>
a > 0
NameError: name 'a' is not defined
Is there a way of catching the exception/error and extracting from it the value 'a'.
I need this because I'm evaluating some dynamically created expressions, and would like to retrieve the names which are not defined in them.
有没有办法捕获异常/错误并从中提取值“a”。我需要这个，因为我正在使用eval一些动态创建的表达式，并且想要检索未在其中定义的名称。
Hope I made myself clear. Thanks! Manuel
希望我说清楚了。谢谢！曼努埃尔
采纳答案by John La Rooy
>>> import re
>>> try:
... a>0
... except (NameError,),e:
... print re.findall("name '(\w+)' is not defined",str(e))[0]
a
If you don't want to use regex, you could do something like this instead
如果你不想使用正则表达式，你可以这样做
>>> str(e).split("'")[1]
'a'
回答by kepkin
>>> import exceptions
>>> try:
... a > 0
... except exceptions.NameError, e:
... print e
...
name 'a' is not defined
>>>
You can parse exceptions string for '' to extract value.
您可以解析 '' 的异常字符串以提取值。
回答by dansalmo
No import exceptionsneeded in Python 2.x
没有import exceptions必要在Python 2.x的
>>> try:
... a > 0
... except NameError as e:
... print e.message.split("'")[1]
...
a
>>>
You assign the reference for 'a' as such:
您为 'a' 分配引用，如下所示：
>>> try:
... a > 0
... except NameError as e:
... locals()[e.message.split("'")[1]] = 0
...
>>> a
0
