Avoiding required nesting of configs

[KennethEnevoldsen]

Hi, I have had the problem that I often want variables defined in the top-most layers of my config (e.g. a logger as seen below), which I then want to refer to in multiple places. This causes a recursion error:

InterpolationDepthError: Recursion limit exceeded in value substitution: option 'logger' in section 'training' contains an interpolation key which cannot be substituted in 10 steps. Raw value: '${logger}'

I don't see any principled reason why that would not be possible (though I might be wrong). My question is simply if I were to find the time to make a PR for this would it be considered useful?

Minimal example:

import catalogue

from confection import Config, registry


class Registry(registry):
    registry = catalogue.create("my_package", "loggers")


@Registry.registry.register("my_logger")
def test_fn(name: str):
    return name

# desired config
config_str_unnested = """
[logger]
@registry = "my_logger"
name = "test_logger"


[training]
batch_size = 32
logger = ${logger}
"""

# current config
config_str_nested = """
[logger]
[logger.logger]
@registry = "my_logger"
name = "test_logger"


[training]
batch_size = 32
logger = ${logger.logger}
"""

if __name__ == "__main__":
    cfg = Config().from_str(text=config_str_nested)
    # works, but is less readable
    cfg = Config().from_str(text=config_str_unnested) 
    # does not work, but is more readable

[svlandeg]

Hey @KennethEnevoldsen - sorry for the slow response to these very reasonable questions / suggestions, we're working through a bit of a backlog for support after the holiday season.

We'd definitely think this would be useful if you'd find the time for a PR.

Just for my understanding - do you want the function called multiple times, or the same object referenced?

[KennethEnevoldsen]

Ideally the same object references, but can see that there might be a challenge there.