Allow for custom resolvers with no arguments

[markcoletti]

Allow for creating resolvers that take no arguments. E.g., OmegaConf.register_new_resolver("cpus", lambda : os.cpu_count)

Currently attempts at this throws an exception.

[24hours]

Passing fake value should work ?

${cpus:temp}

OmegaConf.register_new_resolver("cpus", lambda x : os.cpu_count)

[markcoletti]

That's a kludge that works but is a bit ugly. It'd be cleaner and more intuitive if the package supports my original intent.

[Galileo-Galilei]

I'd love to have this feature too. If you are open to PR's and can give me a rough sketch of what will be impacted in the code, I can give it a try.

[odelalleau]

I just tried it and this is working => closing the issue (please re-open with a specific example if the issue still persists on your side)

[goldegard]

Hi, I'm trying to use custom resolvers with no params and I'm hitting the same issue reported here. Minimal reproducible example:

import random

from omegaconf import OmegaConf

OmegaConf.register_new_resolver("plus_10", lambda x: x + 10)
OmegaConf.register_new_resolver("random_number", lambda: random.randint(0, 1000))

c = OmegaConf.create(
    {
        "key": "${plus_10:990}",
        "key2": "${random_number}",
    }
)

print(c.key, c.key2)

Output:

...
omegaconf.errors.InterpolationKeyError: Interpolation key 'random_number' not found
    full_key: key2
    object_type=dict

Interestingly, adding : with or without any dummy parameter seems to work, but it's not very idiomatic:

import random

from omegaconf import OmegaConf

OmegaConf.register_new_resolver("plus_10", lambda x: x + 10)
OmegaConf.register_new_resolver("random_number", lambda: random.randint(0, 1000))

c = OmegaConf.create(
    {
        "key": "${plus_10:990}",
        "key2": "${random_number:}",
    }
)

print(c.key, c.key2)

Any thoughts?

Additional context

• [x] OmegaConf version: 2.3.0
• [x] Python version: Python 3.10.4
• [x] Operating system: 5.13.0-41-generic #46~20.04.1-Ubuntu SMP Wed Apr 20 13:16:21 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux