python: try except --- During handling of the above exception, another exception occurred

• 第一部分引用自“https://www.pynote.net/archives/1856”，作为引入，可参看原文

在以下代码中，执行后会报出“During handling of the above exception, another exception occurred:”

x = 2
y = 0

try:
    result = x / y
except ZeroDivisionError:
    raise ValueError('raise in exception clause')
    print("=== division by zero!")
else:
    print("result is", result)
finally:
    raise ValueError('raise in finally clause')
    print("executing finally clause")

• 以后部分为原创

“During handling of the above exception, another exception occurred:”是什么意思？

执行下代码，可知是因为后续分支（比如上code中except或finally分支，比如下code中except分支）执行的代码又出错了。

x = 2
y = 0

try:
    result = x / y
except ZeroDivisionError:
    print('这是第一个except')
    result = x / y

输出有：

During handling of the above exception, another exception occurred:

• 处理方法之一：

加入新的try...except...避免该错误，如下：

x = 2
y = 0

try:
    result = x / y
except ZeroDivisionError:

    try:
        print("这是第一个except")
        result = x / y
      
    except Exception as e:
        print("这是第二个except")
        print(repr(e))

顺利执行，不报错“During handling of the above exception, another exception occurred:”，输出为：

这是第一个except
这是第二个except
ZeroDivisionError('division by zero')