[IDEA] Generic `Never` for more explicit exception type-hinting

[abessman (Alexander Bessman)]

See previous discussions on checked exceptions, the conclusion of which were:

@davidism

The answer is pretty definitively “not going to happen” at this point.

Extend type hints to cover exceptions

PEP 484 introduced type hints, at this time documenting exceptions was left to docstrings. I seek to suggest a reason this feature might be desirable along with how it might be used. Error handling in python does an excellent job of keeping the error-path out of the way when writing the normal flow of logic, however for larger code bases it is not always clear what exceptions may be caused by calling existing code. Since these cases are easily missed they may reach a higher level than intended …

What if function definitions could tell the caller "I raise Exceptions"?

Similar to Swift, I think it would add to the expressiveness of the language to be able to type-hint a function which might raise any type of Exception. For example: def login(username: str, password: str) -> User raises: resp = requests.post("/login", { "user": username, "password": password, }) resp.raise_for_status() return User(**resp.json()) Describes a function login which normally returns a User object, but may also raise an Exception. Additionally, what…

Allow for the Hinting of Raised Exceptions Within a Callable

I would love to see Python add the ability to hint exceptions that can be raised within a function/callable. Other languages such as Java have this feature. Something like this for example: def myfunc(x, y) -> [int, (OSError, RuntimeError)]: … Or like this def myfunc(x, y) raises (OSError, RuntimeError) -> int: … Or like this def myfunc(x, y) -> int: raises OSError, RuntimeError … Im not too particular on the actual syntax. This would great for a few reasons: IDE autocom…