@dataclass数据类 / 内置函数的用法

"""
关于第一个Message1类定义的缺点：
① 书写麻烦
② 一旦需要再加一个值进行修改，则整个类中的所有内置函数的代码都需要进行相应的修改
∴ 用第一个Message2就可以把这个问题解决掉
"""

class Message1:
    def __init__(self, mid: int, text: str):
        self.__id: int = mid
        self.__text: str = text

    @property
    def id(self) -> int:
        return self.__id

    @property
    def text(self) -> str:
        return self.__text

    def __repr__(self):
        return f"{self.__class__.__name__}({self.id}, {self.text})"

    def __eq__(self, other):
        if other.__class__ != self.__class__:   # isinstance(other, self):
            return NotImplemented
        else:
            return ((self.id, self.text) == (other.id, other.text))

    def __ne__(self, other):
        result = self.__eq__(other)
        if result is NotImplemented:
            return NotImplemented
        else:
            return not result

    def __hash__(self):
        return hash((self.__class__, self.id, self.text))

    def __lt__(self, other):
        if other.__class__ != self.__class__:
            return NotImplemented
        else:
            return self.id < other.id

    def __le__(self, other):
        if other.__class__ != self.__class__:
            return NotImplemented
        else:
            return self.id <= other.id

    def __gt__(self, other):
        if other.__class__ != self.__class__:
            return NotImplemented
        else:
            return self.id > other.id

    def __ge__(self, other):
        if other.__class__ != self.__class__:
            return NotImplemented
        else:
            return self.id >= other.id

@dataclass
class Message2:
    id: int = None
    text: str = None
    age: int = None

if __name__ == '__main__':
    m1 = Message1(2, 'hello 2')
    m2 = Message1(1, 'hello 1')
    m3 = Message2(3, 'hello 3')
    print(m3)
    print(astuple(m3))
    print(asdict(m3))

    print(m3.__dir__())

Message2(id=3, text='hello 3', age=None)
(3, 'hello 3', None)
{'id': 3, 'text': 'hello 3', 'age': None}
['id', 'text', 'age', '__module__', '__annotations__', '__dict__', '__weakref__', '__doc__', '__dataclass_params__', '__dataclass_fields__', '__init__', '__repr__', '__eq__', '__hash__', '__str__', '__getattribute__', '__setattr__', '__delattr__', '__lt__', '__le__', '__ne__', '__gt__', '__ge__', '__new__', '__reduce_ex__', '__reduce__', '__subclasshook__', '__init_subclass__', '__format__', '__sizeof__', '__dir__', '__class__']

通过m3.__dir__()就可以看到经过@dataclass修饰的数据类，自动初始化了很多内置参数，减少了很多代码的工作量