具有固定键、值类型的不可变/冻结字典子类

class ImmutableDict(dict):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self._frozen = True

    def __setitem__(self, key, value):
        if self._frozen:
            raise TypeError("ImmutableDict is frozen and cannot be modified.")
        super().__setitem__(key, value)

    def __delitem__(self, key):
        if self._frozen:
            raise TypeError("ImmutableDict is frozen and cannot be modified.")
        super().__delitem__(key)

    def update(self, *args, **kwargs):
        if self._frozen:
            raise TypeError("ImmutableDict is frozen and cannot be modified.")
        super().update(*args, **kwargs)

    def freeze(self):
        self._frozen = True

    def is_frozen(self):
        return self._frozen

# 创建一个不可变字典实例
immutable_dict = ImmutableDict({'a': 1, 'b': 2})
immutable_dict.freeze()

# 尝试修改字典会引发异常
try:
    immutable_dict['a'] = 3
except TypeError as e:
    print(e)  # 输出: ImmutableDict is frozen and cannot be modified.