[danpla]

> Expected errors - like "user not found" - should use a value instead of exception. In Python, you can use sentinel objects, or tuples, or None.. lots of options really.

That's why exceptions are called exceptions, not errors. If a routine called openFile() can't open a file, that's a pretty exceptional situation, and it's up to the caller to decide whether the exact reason is an error in their case.

The exception object is already a value that can have not only a message text, but also any data members, so why reinvent the wheel with sentinel objects, tuples, etc.?

> The examples in post, where you catch exception and re-raise Exception back are terrible - what's the point of them? There is no extra clarity, just verbosity. I would defect them in any code review.

Typically, you re-raise an exception after adding some content to it. This may be less important in Python, which gives you a great stack trace, but in a language like C++, the lack of context information makes the exception basically useless.