Type Hinting for Structured Configs

[abefrandsen]

Hi! I'm wondering if there is an established way to type hint a function argument that is a DictConfig but further adheres to a particular structured config schema. Let me illustrate two possibilities -- simply annotating with DictConfig (which is correct but non-specific), or annotating with the structured config schema (specific but incorrect):

from omegaconf import DictConfig
from dataclasses import dataclass

@dataclass
class FooConfig:
    name: str
    age: int

# type hint with DictConfig -- correct but nonspecific
def myfun(fooconfig: DictConfig):
    ...

# type hint with FooConfig -- incorrect but specific
def myfun(fooconfig: FooConfig):
    ...

Is there a way to annotate the fooconfig argument with a valid type hint that clearly indicates it should be consistent with the FooConfig structured config schema?

Thanks!

[abefrandsen]

So I think this issue is relevant -- looks like a generic DictConfig type could eventually be in the works. In my case above, it would look something like:

def myfun(fooconfig: DictConfig[FooConfig]):
    ...

In the meantime, is there any way apart from just using the plain DictConfig annotation?

[omry]

The recommended practice is the second approach (duck typing).
If you really need the underlying object type to match, you can convert the OmegaConf config to object.
See OmegaConf.to_container and OmegaConf.to_object (which is a syntactic sugar using to_container).