Config proxy file to simplify porting of detectron2-like codebases

configproxy.py

class ConfigProxy:
    def __init__(self, cfgobj = None, ConfigProxyPath = '', ConfigProxyRoot = '', ConfigProxySep = '__', **cfgdict):
        self.cfgobj = cfgobj
        self.cfgdict = cfgdict
        self.ConfigProxyRoot = ConfigProxyRoot
        self.ConfigProxyPath = ConfigProxyPath
        self.ConfigProxySep = ConfigProxySep

    def __getattr__(self, key):
        ConfigProxyPath = self.ConfigProxyPath + self.ConfigProxySep + key if self.ConfigProxyPath else key
        ConfigProxyPathWithRoot = self.ConfigProxyRoot + self.ConfigProxySep + ConfigProxyPath if self.ConfigProxyRoot else ConfigProxyPath

        if ConfigProxyPathWithRoot in self.cfgdict:
            return self.cfgdict[ConfigProxyPathWithRoot]

        path = ConfigProxyPath.split(self.ConfigProxySep)
        cfgobj = self.cfgobj
        for i in range(len(path)):
            if hasattr(cfgobj, path[i]):
                cfgobj = getattr(cfgobj, path[i])
                if i == len(path) - 1:
                    return cfgobj
            else:
                break

        return ConfigProxy(cfgobj = self.cfgobj, ConfigProxyPath = ConfigProxyPath, ConfigProxySep = self.ConfigProxySep, ConfigProxyRoot = self.ConfigProxyRoot, **self.cfgdict)
        
        
if __name__ == '__main__':
    # code found in detectron2-based codebaes
    # ConfigProxy can be used for porting to less intrusive style
    class MyModel:
        def __init__(self, cfg__MODEL__DiffusionDet__NUM_CLASSES = 0, cfg = None, **config):
            cfg = ConfigProxy(cfg, ConfigProxyRoot = 'cfg', ConfigProxySep = '__', cfg__MODEL__DiffusionDet__NUM_CLASSES = cfg__MODEL__DiffusionDet__NUM_CLASSES, **config)

            print(cfg.MODEL.DiffusionDet.NUM_CLASSES)
            print(cfg.MODEL.DiffusionDet.DROPOUT)
            print(cfg.MODEL.DiffusionDet.ACTIVATION)


    # can support either config obj
     class config:
        class MODEL:
            class DiffusionDet:
                DROPOUT = 0.5
                NUM_CLASSES = 20
                ACTIVATION = 'relu'
    MyModel(cfg = config)
    # 20
    # 0.5
    # relu
    
    
    # or dicts. can't support both soundly because at getattr time we can't continue resolve dicts if a config object resolves first
    config = dict(cfg__MODEL__DiffusionDet__NUM_CLASSES = 20, cfg__MODEL__DiffusionDet__ACTIVATION = 'relu')
    MyModel(**config)
    # 20
    # <__main__.ConfigProxy object at 0x7f6ab796fd00>
    # relu