Figure out return of a method that returns empty hash on some condition

Question

I'm trying to understand how to make this work:

def someMethod() -> dict[any, any]:
    if not os.path.exists('some path'):
        return {}

    config = {'a': 1, 'b': 2}
    return config

I don't think that's correct. Seeing this error - Declared return type, "dict[Unknown, Unknown]", is partially unknownPylance

The idea is to return empty dict if a path doesn't exist (or on some condition) or correct dict with key-value pairs.

Any ideas?

You could tidy this up a bit with `return {}` instead of a local that you then stomp later anyway. — tadman, May 29 '23 at 15:03
makes sense, removed it in question and also in my local code. Thank you! Any ideas on how to get the return type working — scorpion35, May 29 '23 at 15:09
https://stackoverflow.com/questions/61997937/how-to-solve-type-is-partially-unknown-warning-from-pyright may be relevant — Andrew McClement, May 29 '23 at 15:19
As a practical point, `dict[string,int]` might be an alternative. — Andrew McClement, May 29 '23 at 15:21

ftorre · Accepted Answer · 2023-05-29T15:25:40.933

5

Lowercase any is a Python built-in function and not a type. Instead, you have to import capital Any from the typing module.

from typing import Any
import os

def someMethod() -> dict[Any, Any]:
    if not os.path.exists('some path'):
        return {}

    config = {'a': 1, 'b': 2}
    return config

edited May 29 '23 at 15:25

answered May 29 '23 at 15:16

ftorre

501
1
9

Since the returned dict is always a `dict[str, int]` that might be better — or even `typing.Mapping[str, int]` if the caller isn’t meant to modify it. – Samwise May 29 '23 at 16:30

Figure out return of a method that returns empty hash on some condition

1 Answers1