1. Dataclass

传统面向对象编程如下所示：

class User:
    def __init__(self, name: str, age: int, favourite_ic: str) -> None:
        self.name = name
        self.age = age
        self.favourite_ic = favourite_ic
 
    def is_adult(self) -> bool:
        """Return True if user is an adult, else False."""
        return self.age >= 18
 
 
if __name__ == '__main__':
    john = User('John', 29, '555')
    print(john)
    # prints "<__main__.User object at 0x0076E610>"

<__main__.User object at 0x000002B80BF125F8>

编写这种类时具有通用的模式，Python 3.7 中引入了 dataclass，使得这种类更容易声明，更加可读。

只需要使用 @dataclass 装饰类，对 self 的赋值就会自动发生，类型注解是强制的。

from dataclasses import dataclass
 
@dataclass
class User:
    name: str
    age: int
    favourite_ic: str
 
    def is_adult(self) -> bool:
        """Return True if user is an adult, else False."""
        return self.age >= 18
 
if __name__ == '__main__': 
    john = User('John', 29, '555') 
    print(john) 
    # prints "User(name='John', age=29, favourite_ic='555')"