模拟类取值

from collections import abc


class CommonDict:
    """
    模拟元类，拟实现a.b[0].c这样的方式获取结果
    有个问题：路径里的字符必须满足python变量的命名规则
    """

    def __init__(self, mapping):
        if isinstance(mapping, abc.Mapping):
            self._data_ = dict(mapping)
        elif isinstance(mapping, abc.MutableSequence):
            self._data_ = list(mapping)
        else:
            self._data_ = mapping

    def __getitem__(self, item):
        return CommonDict(self._data_[item])

    def __getattr__(self, item):
        if hasattr(self._data_, item):
            return getattr(self._data_, item)
        else:
            return CommonDict(self._data_[item])