_environ_config.py 文件源码

def _to_config(config_cls, default_get, environ, prefix):
    vals = {}
    for a in attr.fields(config_cls):
        try:
            ce = a.metadata[CNF_KEY]
        except KeyError:
            continue
        if ce.sub_cls is None:
            get = ce.callback or default_get
            val = get(environ, a.metadata, prefix, a.name)
        else:
            val = _to_config(
                ce.sub_cls, default_get, environ,
                prefix + ((a.name if prefix else a.name),)
            )

        vals[a.name] = val
    return config_cls(**vals)