如何编写一个高效的__dict__重载函数？

class EfficientDictMeta(type):
    def __getattr__(cls, name):
        return cls.__dict__.get(name)

class EfficientDict(metaclass=EfficientDictMeta):
    def __init__(self):
        self._data = {}

    def __getattr__(self, name):
        return self._data.get(name)

    def __setattr__(self, name, value):
        self._data[name] = value

    def __delattr__(self, name):
        del self._data[name]

    def __dir__(self):
        return list(self._data.keys())

# 示例用法
obj = EfficientDict()
obj.name = "John"
obj.age = 30

print(obj.name)  # 输出: John
print(obj.age)  # 输出: 30
print(dir(obj))  # 输出: ['name', 'age']