在其功能之外拾取异常

Question

我有一个基于文本的程序，它在“while True:”样式循环中使用菜单和子菜单。您可以通过顶部菜单进入子菜单 - 已编辑以包含代码。

输出如下所示：

1 Collect Attachments

2 View Senders

3 Edit Senders

4 Quit

Choose an option: 1

Chose Collect Attachments

Enter a date dd-mm-yyyy: 21-01-2020

Enter how many days previous to search through: 7

Your search starts from 2020-01-21 00:00:00 and ends on 2020-01-14

0 Search Any

1 Hazel Blue

2 Duo Security

3 Esker Australia Pty Ltd

4 iiNet Billing Team

5 TeamViewer Sales

6 ple.com.au Gnangara Warehouse Team

7 [e-mail]

8 Amazon Web Services

There are 9 options.

Choose a sender (blank to exit):

You did not enter a valid number (ValueError)

问题是 ValueError 不应该出现在子菜单中。这都是自学的，所以我想我不明白异常处理是如何完成的。

Answer 1

这是问题：>>> int("")Traceback (most recent call last):&nbsp; File "<stdin>", line 1, in <module>ValueError: invalid literal for int() with base 10: ''因此，当您在子菜单中说“空白退出”时，您应该：在转换为数字之前检查空字符串只使用字符串顺便说一句，学习logging包并logging.exception在抑制异常时使用通常很有用。此外，try您使用的涵盖数十行代码的大型子句通常不受欢迎，因为它很容易捕获意外异常，然后您已经注意到很难调试它。您通常应该尽可能地限制您的try条款，当然您的里程可能会有所不同。

Answer 2

如果在 topMenu 中生成任何异常，您可以尝试此操作，那么它将不会进入子菜单，否则它将进入子菜单并执行操作。def main():&nbsp; &nbsp; &nbsp;def topMenu():&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; while True:&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; try:&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; # code if generate exception&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; subMenu()&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; # you can fetch specific exception or general&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; except Exception as e:&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; print(e)&nbsp; &nbsp; &nbsp; &nbsp; def subMenu():&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; print("in submenu")&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; # code here...&nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; topMenu()&nbsp;main()