raise和raise from捕获异常

raise/from 捕获：可同时抛出自定义异常和原生异常

>>> try:
...     a=2/0
... except Exception as e:
...     raise Exception('分母不能为0') from  e
...
Traceback (most recent call last):
  File "<stdin>", line 2, in <module>
ZeroDivisionError: division by zero

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "<stdin>", line 4, in <module>
Exception: 分母不能为0
>>>

raise自定义异常中捕获：可同时抛出自定义异常和原生异常

>>> try:
...     a=2/0                               
... except Exception as e:                  
...     raise Exception(f'分母不能为0，{e}')
... 
Traceback (most recent call last):                                 
  File "<stdin>", line 2, in <module>                              
ZeroDivisionError: division by zero                                
                                                                   
During handling of the above exception, another exception occurred:
                                                                   
Traceback (most recent call last):                                 
  File "<stdin>", line 4, in <module>                              
Exception: 分母不能为0，division by zero                           
>>>   

只raise抛出原生异常：只抛出原生异常

>>> try:
...     a=2/0
... except Exception as e:
...     raise e
... 
Traceback (most recent call last):
  File "<stdin>", line 4, in <module>
  File "<stdin>", line 2, in <module>
ZeroDivisionError: division by zero
>>>

只raise自定义异常：可排除自定义异常和原生异常

>>> try:
...     a=2/0
... except Exception as e:
...     raise Exception('分母不能为0')
... 
Traceback (most recent call last):
  File "<stdin>", line 2, in <module>
ZeroDivisionError: division by zero

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<stdin>", line 4, in <module>
Exception: 分母不能为0
>>>