python如何通过注册表动态管理组件

class Registry:
    def __init__(self, name, scope=None, parent=None):
        self.name = name
        self.scope = scope
        self.parent = parent
        self._module_dict = {}
    def register_module(self, name=None):
        def _register(cls):
            module_name = name or cls.__name__
            if module_name in self._module_dict:
                raise KeyError(f'{module_name} is already registered in {self.scope}::{self.name}')
            self._module_dict[module_name] = cls
            return cls
        return _register
    def get(self, name):
        if name in self._module_dict:
            return self._module_dict[name]
        elif self.parent:
            return self.parent.get(name)
        else:
            raise KeyError(f'{name} is not registered in {self.scope}::{self.name} and no parent registry to fallback.')
    def build(self, cfg):
        module_name = cfg['type']
        module_cls = self.get(module_name)
        return module_cls(**{k: v for k, v in cfg.items() if k != 'type'})

from torch import nn
# 创建父注册表
MODELS = Registry('models', scope='mmengine')
# 注册一个模块到父注册表
@MODELS.register_module()
class ResNet(nn.Module):
    def __init__(self, layers):
        self.layers = layers
    def forward(self, x):
        return x
# 创建子注册表，指定 MODELS 为父注册表
DETECTORS = Registry('detectors', scope='mmengine', parent=MODELS)
# 注册一个模块只到子注册表
@DETECTORS.register_module()
class FasterRCNN(nn.Module):
    def __init__(self, num_classes):
        self.num_classes = num_classes
    def forward(self, x):
        return x
# 从子注册表构建 ResNet 实例，尽管它是在父注册表中注册的
resnet_instance = DETECTORS.build({'type': 'ResNet', 'layers': 50})
print(resnet_instance)
# 直接从子注册表构建 FasterRCNN 实例
fasterrcnn_instance = DETECTORS.build({'type': 'FasterRCNN', 'num_classes': 80})
print(fasterrcnn_instance)