异常处理

def demo():
    try:
        1 / 0
    except Exception as e:
        print(type(e)) #<class 'ZeroDivisionError'>

自定义异常

class CustomError(Exception):
    pass

异常链

class CustomError(Exception):
    pass


def demo():
    try:
        1 / 0
    except Exception as e:
        print(type(e)) #<class 'ZeroDivisionError'>
        raise CustomError() from e

<class 'ZeroDivisionError'>
Traceback (most recent call last):
  File "/Users/tiger/work/customer/dd.py", line 23, in demo
    1 / 0
ZeroDivisionError: division by zero

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

Traceback (most recent call last):
  File "/Users/tiger/work/customer/dd.py", line 39, in <module>
    demo()
  File "/Users/tiger/work/customer/dd.py", line 26, in demo
    raise CustomError() from e
__main__.CustomError

问题

  1. 对于 demo 而言, 他的异常是什么?

    def wapper():
    try:
        demo()
    except Exception as e:
        # print(e.__cause__, type(e.__cause__))
        print("error")
        print(e)
        print("end")


<class 'ZeroDivisionError'>
error

end

    image-20211009200333580

    是的, 结果为空, 因为此时 e 为 CustomError, 并没有写入 args

  2. 对于上面的 wapper 来说, 如何得到真实的 error, 即 1/0 (ZeroDivisionError)

    def wapper():
    try:
        demo()
    except Exception as e:
        print(e.__cause__, type(e.__cause__))
        print("error")
        print(e)
        print("end")


<class 'ZeroDivisionError'>
division by zero <class 'ZeroDivisionError'>
error

end