创建自定义例外的最佳做法是什么？

Question

创建自定义异常时，最好的做法是为每个自定义异常创建一个单独的类文件，或者将自定义异常附加到它们所关联的类文件的末尾，或者创建一个文件（例如CustomExceptions.cs）并在那里添加自定义例外？

Answer 1

One class per file is always a good rule.

The other basics:

• Mark your exception as [Serializable]
• Overload all the System.Exception constructors
• Don't inherit from System.ApplicationException

Answer 2

Well ... I would say that you should follow the rule of one class per file, except in case if this exception is just for "internal" functionality in your class. Then you can make it declared inside the class. However, if exposed by any means to outside world, separate it from the class. This exposure could also be seen from the actual probability that this exception goes unhanded to the users of your class. In this case, I would also expose it and would not declare it inside.

Answer 3

As others have stated, one class per file rule is ideal. Another way to think of it, if you have a large application consisting of many modules, you will have multiple namespaces and it's important to keep the exceptions that a certain class method (or set of classes/methods) can throw within their respective namespaces. This makes the code more readable and the reasoning behind your custom exceptions easier to decipher for other developers ... Or for you in 6 months when you forgot why you made half of them :)