一、基本用法

# 从一个类建立一个对象
# __new__ 从class建立一个object过程
# __init__ 有了object初始化过程
class Language:
    def __new__(cls, *args, **kwargs):
        print("__new__")
        return super().__new__(cls)

    def __init__(self):
        print("__init__")
        
language = Language()
-------------------------
__new__
__init__

二、类似负载分担的作用

可以在实例化时根据输入参数选择对应的类

class Sex:
    def __new__(cls, *args, **kwargs):
        if kwargs.get('sex') == 'man':
            return Man()
        elif kwargs.get('sex') == 'woman':
            return Woman()
        else:
            return super(Sex, cls).__new__(cls)

    def say(self):
        print("我看你不是人！")

class Man:
    def say(self):
        print("this is a man")
class Woman:
    def say(self):
        print("this is a woman")

sex = Sex(sex="man")
sex.say()
sex = Sex(sex="woman")
sex.say()
sex = Sex(sex="waixingren")
sex.say()

---------------------------
this is a man
this is a woman
我看你不是人！