How to decrease the type checking paranoia?

[pelissarisergioo]

I've been trying to have my code as clear as possible in terms of typing suggestions but I always end up ignoring a few of them to prevent the code quality violation, the one that most annoys me is this example below.

I'm writing one API service then usually what I do is:

• create a config.py file with some content like this:

from os import getenv as env

CONNECTION_STRING = env("CONNECTION_STRING")
... and some more entries like this

then I assert them

env_vars = [CONNECTION_STRING]
for vars in env_vars:
  assert vars is not None

From this part, I'm already making sure that this variable cannot be None, but when I import this constant in another file that I may have or not use it as an argument I always end up with something like...

Argument of type "str | None| cannot be assigned to parameter...

So my point is I don't want to check if these constants are None on every piece of code that I need to use, so maybe I'm not sure if I'm doing it properly or indeed we need some extra, extra, extra value validation before using it...

[JelleZijlstra]

Maybe create a helper function like this:

def env_not_none(key: str) -> str:
    value = os.getenv(key)
    assert value is not None, f"failed to find {key}"
    return value

CONNECTION_STRING = env_not_none("CONNECTION_STRING")

[pelissarisergioo]

that sounds great, just tried and worked perfectly, also it answered some extra answers that I had in mind. Thanks!

[Akuli]

You could also use os.environ["CONNECTION_STRING"]. That will fail if the env var doesn't exist.