Registry

YAHP also supports instantiating concrete sub-classes of abstract fields directly from the YAML or the command line.

Singleton Example

Consider the following script that defines the Hparams:

# Copyright 2021 MosaicML. All Rights Reserved.

import abc
import dataclasses
import os
from typing import List

import yahp as hp


@dataclasses.dataclass
class Person(hp.Hparams, abc.ABC):
    name: str = hp.required('name')


@dataclasses.dataclass
class AdultHparams(Person):
    num_children: int = hp.optional('num_children', default=0)


@dataclasses.dataclass
class ChildHparams(Person):
    parents: List[str] = hp.required('parents')


@dataclasses.dataclass
class FooHparams(hp.Hparams):
    hparams_registry = {
        'owner':
            {  # key "owner" corresponds to field name "owner" below
                'adult': AdultHparams,
                'child': ChildHparams,
            }
    }
    owner: Person = hp.required('owner')

Suppose registry_foo.yaml contains the following:

owner:
  child:
    name: Bob
    parents:
      - Alice
      - Charlie

Then, the following example will load owner to the child.

foo_hparams = FooHparams.create(os.path.join(os.path.dirname(__file__), 'registry_foo.yaml'))
assert type(foo_hparams.owner) is ChildHparams

print(foo_hparams)

It will print the following:

FooHparams:
    owner:
        child:
            name: Bob
            parents:
            - Alice
            - Charlie

List Example

Suppose we wanted to permit multiple owners. Consider the following Hparams:

@dataclasses.dataclass
class BarHparams(hp.Hparams):
    hparams_registry = {
        'owners':
            {  # key "owners" corresponds to field name "owners" below
                'adult': AdultHparams,
                'child': ChildHparams,
            }
    }
    owners: List[Person] = hp.required('owners')

Suppose registry_bar.yaml contains the following:

owners:
  - adult:
      name: Alice
      num_children: 1
  - child:
      name: Bob
      parents:
        - Alice
        - Charlie

Then, the following example will load owners to the adult and the child.

bar_hparams = BarHparams.create(os.path.join(os.path.dirname(__file__), 'registry_bar.yaml'))
assert type(bar_hparams.owners[0]) is AdultHparams
assert type(bar_hparams.owners[1]) is ChildHparams

print(bar_hparams)

It will print the following:

BarHparams:
    owners:
    - adult:
        name: Alice
        num_children: 1
    - child:
        name: Bob
        parents:
        - Alice
        - Charlie