openff-units 0.2.1 breaks mypy for openff-models

[dwhswenson]

Not sure if this belongs here or on openff-models, but here's a MCVE:

# file named example.py
from openff.models.types import FloatQuantity
import openff.units  # type: ignore

print(f"{openff.units.__version__=}")
models_quantity: FloatQuantity["kelvin"]

Then, with openff-units 0.2.0 (and openff-models at current release, 0.0.5):

$ python example.py && mypy example.py
openff.units.__version__='0.2.0'
Success: no issues found in 1 source file

With openff-units 0.2.1:

$ python example.py && mypy example.py
openff.units.__version__='0.2.1'
example.py:5: error: Variable "openff.models.types.FloatQuantity" is not valid as a type  [valid-type]
example.py:5: note: See https://mypy.readthedocs.io/en/stable/common_issues.html#variables-vs-type-aliases
example.py:5: error: Name "kelvin" is not defined  [name-defined]
Found 2 errors in 1 file (checked 1 source file)

see also OpenFreeEnergy/openfe#461

[mattwthompson]

0.2.1 breaks lots of stuff for reasons that have caused me physiological aging (blood pressure, hair loss, etc.). For now the recommendation is to stick to 0.2.0, since I think that works, and we'll have fixes out as soon as we can (one attempt at #68).

[mattwthompson]

I'm also not sure if this affects both Pint 0.21 and 0.22, but I'm pretty sure one of them works with 0.2.0

[mattwthompson]

With #84 I have it passing on Pint 0.21, 0.22, 0.23

With openforcefield/openff-models#42 it's also passing with Pydantic models. The SomeQuantity['preferred_unit'] paradigm is likely going away, I unfortunately don't think that pattern is future-compatible with how tooling interprets string literals brackets inside of things that look like types.

#77 would be my preferred solution but that's around three years out of being compatible with OpenFF's Python support

[mattwthompson]

This still sticks around on the v1 API, it should be gone with v2

$ cat example.py && python example.py && mypy example.py                                                                           14:00:02  ☁  0.2.2 ☂
# file named example.py
import openff.units
import openff.models

from openff.models.types import FloatQuantity
from pydantic.v1 import BaseModel
from openff.units import Quantity


print(f"{openff.units.__version__=}")
print(f"{openff.models.__version__=}")


class Model(BaseModel):
    temperature: FloatQuantity["kelvin"]


print(f"{Model(temperature=Quantity("419.0 kelvin")).temperature=}")
openff.units.__version__='0.2.2'
openff.models.__version__='0.1.2'
Model(temperature=Quantity("419.0 kelvin")).temperature=<Quantity(419.0, 'kelvin')>
example.py:15: error: Variable "openff.models.types.FloatQuantity" is not valid as a type  [valid-type]
example.py:15: note: See https://mypy.readthedocs.io/en/stable/common_issues.html#variables-vs-type-aliases
example.py:15: error: Name "kelvin" is not defined  [name-defined]
Found 2 errors in 1 file (checked 1 source file)

[mattwthompson]

These code paths are outdated now - closing, let us know if this needs to be revived