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# Copyright (c) Facebook, Inc. and its affiliates. | |
import collections.abc as abc | |
import dataclasses | |
import logging | |
from typing import Any | |
from detectron2.utils.registry import _convert_target_to_string, locate | |
__all__ = ["dump_dataclass", "instantiate"] | |
def dump_dataclass(obj: Any): | |
""" | |
Dump a dataclass recursively into a dict that can be later instantiated. | |
Args: | |
obj: a dataclass object | |
Returns: | |
dict | |
""" | |
assert dataclasses.is_dataclass(obj) and not isinstance( | |
obj, type | |
), "dump_dataclass() requires an instance of a dataclass." | |
ret = {"_target_": _convert_target_to_string(type(obj))} | |
for f in dataclasses.fields(obj): | |
v = getattr(obj, f.name) | |
if dataclasses.is_dataclass(v): | |
v = dump_dataclass(v) | |
if isinstance(v, (list, tuple)): | |
v = [dump_dataclass(x) if dataclasses.is_dataclass(x) else x for x in v] | |
ret[f.name] = v | |
return ret | |
def instantiate(cfg): | |
""" | |
Recursively instantiate objects defined in dictionaries by | |
"_target_" and arguments. | |
Args: | |
cfg: a dict-like object with "_target_" that defines the caller, and | |
other keys that define the arguments | |
Returns: | |
object instantiated by cfg | |
""" | |
from omegaconf import ListConfig, DictConfig, OmegaConf | |
if isinstance(cfg, ListConfig): | |
lst = [instantiate(x) for x in cfg] | |
return ListConfig(lst, flags={"allow_objects": True}) | |
if isinstance(cfg, list): | |
# Specialize for list, because many classes take | |
# list[objects] as arguments, such as ResNet, DatasetMapper | |
return [instantiate(x) for x in cfg] | |
# If input is a DictConfig backed by dataclasses (i.e. omegaconf's structured config), | |
# instantiate it to the actual dataclass. | |
if isinstance(cfg, DictConfig) and dataclasses.is_dataclass(cfg._metadata.object_type): | |
return OmegaConf.to_object(cfg) | |
if isinstance(cfg, abc.Mapping) and "_target_" in cfg: | |
# conceptually equivalent to hydra.utils.instantiate(cfg) with _convert_=all, | |
# but faster: https://github.com/facebookresearch/hydra/issues/1200 | |
cfg = {k: instantiate(v) for k, v in cfg.items()} | |
cls = cfg.pop("_target_") | |
cls = instantiate(cls) | |
if isinstance(cls, str): | |
cls_name = cls | |
cls = locate(cls_name) | |
assert cls is not None, cls_name | |
else: | |
try: | |
cls_name = cls.__module__ + "." + cls.__qualname__ | |
except Exception: | |
# target could be anything, so the above could fail | |
cls_name = str(cls) | |
assert callable(cls), f"_target_ {cls} does not define a callable object" | |
try: | |
return cls(**cfg) | |
except TypeError: | |
logger = logging.getLogger(__name__) | |
logger.error(f"Error when instantiating {cls_name}!") | |
raise | |
return cfg # return as-is if don't know what to do | |