def build_from_cfg(cfg, registry, default_args=None):
"""Build a module from config dict.
Args:
cfg (dict): Config dict. It should at least contain the key "type".
registry (:obj:`Registry`): The registry to search the type from.
default_args (dict, optional): Default initialization arguments.
Returns:
object: The constructed object.
"""
if not isinstance(cfg, dict):
raise TypeError(f'cfg must be a dict, but got {type(cfg)}')
if 'type' not in cfg:
if default_args is None or 'type' not in default_args:
raise KeyError(
'`cfg` or `default_args` must contain the key "type", '
f'but got {cfg}\n{default_args}')
if not isinstance(registry, Registry):
raise TypeError('registry must be an mmcv.Registry object, '
f'but got {type(registry)}')
if not (isinstance(default_args, dict) or default_args is None):
raise TypeError('default_args must be a dict or None, '
f'but got {type(default_args)}')
args = cfg.copy()
if default_args is not None:
for name, value in default_args.items():
args.setdefault(name, value)
obj_type = args.pop('type')
if is_str(obj_type):
obj_cls = registry.get(obj_type)
if obj_cls is None:
raise KeyError(
f'{obj_type} is not in the {registry.name} registry')
elif inspect.isclass(obj_type):
obj_cls = obj_type
else:
raise TypeError(
f'type must be a str or valid type, but got {type(obj_type)}')
return obj_cls(**args)
def build_from_cfg(cfg, registry, default_args=None): """Build a module from config dict.