python - 处理 Python 中的多个 KeyError

Question

当我两次 try catch KeyError 时，出现此错误。 python 中是否有任何东西可以阻止您两次 try catch 相同的错误？

$ ./scratch.py
try getting a
can't get a try getting b
Traceback (most recent call last):
  File "./scratch.py", line 13, in <module>
    print dict['b']
KeyError: 'b'

简化代码如下

dict={}
dict['c'] = '3'

try:
        print 'try getting a'
        print dict['a']
except KeyError:
        print 'can\'t get a try getting b'
        print dict['b']
except:
        print 'can\'t get a or b'

Answer 1

我会用一个简单的 for 循环来做到这一点:

>>> d = {'c': 1}
>>> keys = ['a', 'b', 'c']
>>> for key in keys:
...     try:
...         value = d[key]
...         break
...     except KeyError:
...         pass
... else:
...     raise KeyError('not any of keys in dict')
... 
>>> value
1
>>> key
'c'

如果你想在一行中完成:

key, value = next((k, d[k]) for k in keys if k in d)