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# Copyright (c) Facebook, Inc. and its affiliates. | |
import dataclasses | |
import logging | |
from collections import abc | |
from typing import Any | |
from omegaconf import DictConfig | |
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 | |
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 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 AttributeError: | |
# 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 | |
class LazyCall: | |
""" | |
Wrap a callable so that when it's called, the call will not be execued, | |
but returns a dict that describes the call. | |
LazyCall object has to be called with only keyword arguments. Positional | |
arguments are not yet supported. | |
Examples: | |
:: | |
layer_cfg = LazyCall(nn.Conv2d)(in_channels=32, out_channels=32) | |
layer_cfg.out_channels = 64 | |
layer = instantiate(layer_cfg) | |
""" | |
def __init__(self, target): | |
if not (callable(target) or isinstance(target, (str, abc.Mapping))): | |
raise TypeError( | |
"target of LazyCall must be a callable or defines a callable! Got {target}" | |
) | |
self._target = target | |
def __call__(self, **kwargs): | |
kwargs["_target_"] = self._target | |
return DictConfig(content=kwargs, flags={"allow_objects": True}) | |