mypy question
Thomas Passin
list1 at tompassin.net
Sat Dec 30 09:14:05 EST 2023
On 12/29/2023 10:02 AM, Karsten Hilbert via Python-list wrote:
> I agree that mypy's grasp of my intent from
>
> queries:list[dict[str, str | list | dict[str, Any]]]=None,
>
> into
>
> "List[Dict[str, Union[str, List[Any], Dict[str, Any]]]]"
>
> seems accurate. I just don't understand why list[dict[str,
> str]] should not pass that construct.
I made a tiny test program with your type signature, and got this error
message from mypy:
c:\temp\python\typing_test.py:3: error: X | Y syntax for unions requires
Python 3.10 [syntax]
Aside from that, this variation causes no mypy error (you must use
Sequence instead of List), and is also more clear about what you are
trying to get:
from typing import Union, Sequence, Dict
DictType1 = Dict[str, str]
DictType2 = Dict[str, Sequence]
DictType3 = Dict[str, Dict]
QueryType = Sequence[Union[DictType1, DictType2, DictType3]]
def test_typing(queries:QueryType=None):
print(type(queries))
d1 = {'k1': 'v1', 'k2': 'v2'}
queries = [d1,]
test_typing(queries)
I'm not sure if this captures exactly what you want, but it avoids the
problem where mypy does not regard str and Union[str, list] as
equivalent types. I tested this using Python 3.12.
More information about the Python-list
mailing list