类 #

python 3 中已经默认就帮你加载了 object 了（即便你没有写上 object）

python 2.x	python 2.x	python 3.x	python 3.x
不含 object	含 object	不含 object	含 object
`__doc__`	`__doc__`	`__doc__`	`__doc__`
`__module__`	`__module__`	`__module__`	`__module__`
	`__class__`	`__class__`	`__class__`
	`__delattr__`	`__delattr__`	`__delattr__`
	`__dict__`	`__dict__`	`__dict__`
	`__format__`	`__format__`	`__format__`
	`__getattribute__`	`__getattribute__`	`__getattribute__`
	`__hash__`	`__hash__`	`__hash__`
	`__init__`	`__init__`	`__init__`
	`__new__`	`__new__`	`__new__`
	`__reduce__`	`__reduce__`	`__reduce__`
	`__reduce_ex__`	`__reduce_ex__`	`__reduce_ex__`
	`__repr__`	`__repr__`	`__repr__`
	`__setattr__`	`__setattr__`	`__setattr__`
	`__sizeof__`	`__sizeof__`	`__sizeof__`
	`__str__`	`__str__`	`__str__`
	`__subclasshook__`	`__subclasshook__`	`__subclasshook__`
	`__weakref__`	`__weakref__`	`__weakref__`
		`__dir__`	`__dir__`
		`__eq__`	`__eq__`
		`__ge__`	`__ge__`
		`__gt__`	`__gt__`
		`__le__`	`__le__`
		`__lt__`	`__lt__`
		`__ne__`	`__ne__`
		`__init_subclass__`	`__init_subclass__`

类方法 __init_subclass__ 从 3.6 （whatsnew3.6）引入，作用是可以在不使用元类的情况下改变子类的行为。严格来说它不属于元类编程，但也能达到编辑其他类的一种手段。

参考：