Hydra instantiation of tuple resolved from OmegaConf custom resolver fails for nested config files

Question

OmegaConf allows you to register a custom resolver. Here is an example of resolving a tuple.

def resolve_tuple(*args):
    return tuple(args)

OmegaConf.register_new_resolver("tuple", resolve_tuple)

This can be used to resolve a value in a config file with a structure like ${tuple:1,2} to a tuple (1, 2). Along with hydra.utils.instantiate this can be used to create objects that contain or utilize tuples. For example:

config.yaml

obj:
  tuple: ${tuple:1,2}

test.py

import hydra
import hydra.utils as hu

from omegaconf import OmegaConf


def resolve_tuple(*args):
    return tuple(args)


OmegaConf.register_new_resolver('tuple', resolve_tuple)


@hydra.main(config_path='conf', config_name='config_test')
def main(cfg):
    obj = hu.instantiate(cfg.obj, _convert_='partial')
    print(obj)


if __name__ == '__main__':
    main()

Running this example returns:

$ python test.py
{'tuple': (1, 2)}

However, imagine you had a much more complex config structure. You may want to use interpolation to bring in configs from other files like so.

tuple/base.yaml

tuple: ${tuple:1,2}

config.yaml

defaults:
  - tuple: base
  - _self_

obj:
  tuple: ${tuple}

Running this example you get an error:

$ python test.py
Error executing job with overrides: []
Traceback (most recent call last):
  File "test.py", line 16, in main
    obj = hu.instantiate(cfg.obj, _convert_='partial')
  File "/Users/me/anaconda3/envs/my_env/lib/python3.7/site-packages/hydra/_internal/instantiate/_instantiate2.py", line 175, in instantiate
    OmegaConf.resolve(config)
omegaconf.errors.UnsupportedValueType: Value 'tuple' is not a supported primitive type

Set the environment variable HYDRA_FULL_ERROR=1 for a complete stack trace.

The full traceback from hydra is:

Error executing job with overrides: []
Traceback (most recent call last):
  File "test.py", line 21, in <module>
    main()
  File "/Users/me/anaconda3/envs/my_env/lib/python3.7/site-packages/hydra/main.py", line 52, in decorated_main
    config_name=config_name,
  File "/Users/me/anaconda3/envs/my_env/lib/python3.7/site-packages/hydra/_internal/utils.py", line 378, in _run_hydra
    lambda: hydra.run(
  File "/Users/me/anaconda3/envs/my_env/lib/python3.7/site-packages/hydra/_internal/utils.py", line 214, in run_and_report
    raise ex
  File "/Users/me/anaconda3/envs/my_env/lib/python3.7/site-packages/hydra/_internal/utils.py", line 211, in run_and_report

    return func()
  File "/Users/me/anaconda3/envs/my_env/lib/python3.7/site-packages/hydra/_internal/utils.py", line 381, in <lambda>
    overrides=args.overrides,
  File "/Users/me/anaconda3/envs/my_env/lib/python3.7/site-packages/hydra/_internal/hydra.py", line 111, in run
    _ = ret.return_value
  File "/Users/me/anaconda3/envs/my_env/lib/python3.7/site-packages/hydra/core/utils.py", line 233, in return_value
    raise self._return_value
  File "/Users/me/anaconda3/envs/my_env/lib/python3.7/site-packages/hydra/core/utils.py", line 160, in run_job
    ret.return_value = task_function(task_cfg)
  File "test.py", line 17, in main
    model = hu.instantiate(cfg.obj, _convert_='partial')
  File "/Users/me/anaconda3/envs/my_env/lib/python3.7/site-packages/hydra/_internal/instantiate/_instantiate2.py", line 175, in instantiate
    OmegaConf.resolve(config)
  File "/Users/me/anaconda3/envs/my_env/lib/python3.7/site-packages/omegaconf/omegaconf.py", line 792, in resolve
    omegaconf._impl._resolve(cfg)
  File "/Users/me/anaconda3/envs/my_env/lib/python3.7/site-packages/omegaconf/_impl.py", line 40, in _resolve
    _resolve_container_value(cfg, k)
  File "/Users/me/anaconda3/envs/my_env/lib/python3.7/site-packages/omegaconf/_impl.py", line 19, in _resolve_container_value
    _resolve(resolved)
  File "/Users/me/anaconda3/envs/my_env/lib/python3.7/site-packages/omegaconf/_impl.py", line 40, in _resolve
    _resolve_container_value(cfg, k)
  File "/Users/me/anaconda3/envs/my_env/lib/python3.7/site-packages/omegaconf/_impl.py", line 23, in _resolve_container_value
    node._set_value(resolved._value())
  File "/Users/me/anaconda3/envs/my_env/lib/python3.7/site-packages/omegaconf/nodes.py", line 44, in _set_value
    self._val = self.validate_and_convert(value)
  File "/Users/me/anaconda3/envs/my_env/lib/python3.7/site-packages/omegaconf/nodes.py", line 57, in validate_and_convert
    return self._validate_and_convert_impl(value)
  File "/Users/me/anaconda3/envs/my_env/lib/python3.7/site-packages/omegaconf/nodes.py", line 134, in _validate_and_convert_impl
    f"Value '{t.__name__}' is not a supported primitive type"
omegaconf.errors.UnsupportedValueType: Value 'tuple' is not a supported primitive type

If you really dig around in the omegaconf code in the trace you will find that there is a flag for the config object allow_objects that is True in the example that passes and None in the example that does not. What is interesting is that in the _instantaite2.py file just before calling Omegaconf.resolve(config) several flags are set, one being allow_objects as True.

Is the intended behavior for these interpolated/resolved values populated from separate files to override this flag? If so, is there some way to ensure that the allow_objects flag is (or remains) true for all resolved and interpolated values?

Jasha · Accepted Answer · 2021-10-20T23:34:48.067

I think there is some confusion because you are using the word tuple for multiple different purposes :)

Here is an example that works for me:

# my_app.py
import hydra
import hydra.utils as hu

from omegaconf import OmegaConf

def resolve_tuple(*args):
    return tuple(args)

OmegaConf.register_new_resolver('as_tuple', resolve_tuple)

@hydra.main(config_path='conf', config_name='config')
def main(cfg):
    obj = hu.instantiate(cfg.obj, _convert_='partial')
    print(obj)

if __name__ == '__main__':
    main()

# conf/config.yaml
defaults:
  - subdir: base
  - _self_

obj:
  a_tuple: ${subdir.my_tuple}

# conf/subdir/base.yaml
my_tuple: ${as_tuple:1,2}

$ python my_app.py  # at the command line:
{'a_tuple': (1, 2)}

The main difference here is that we've got a_tuple: ${subdir.my_tuple} instead of a_tuple: ${my_tuple}.

Notes:

Tuples may be supported by OmegaConf as a first-class type at some point in the future. Here's the relevant issue: https://github.com/omry/omegaconf/issues/392
The allow_objects flag that you mentioned is undocumented and it's behavior is subject to change.

Good to know about the issue. While this works, unfortunately it's still easy to find ways to break this with the same error. Namely if tried to access the `obj` key using interpolation it will break the same way. May just have to stick to using a list in yaml for now. — Grr, Oct 21 '21 at 14:51
Not sure what you mean about accessing the obj key. But yes, lists are definitely more well-supported at the moment. — Jasha, Oct 21 '21 at 16:11

Hydra instantiation of tuple resolved from OmegaConf custom resolver fails for nested config files

1 Answers1