python中几个get

class Dept(object):
    def __init__(self, x):
        self.x = x

    def __get__(self, instance, owner):
        print('__get__: instance:{} owner:{}'.format(instance, owner))
        # if not instance:
        #     return self
        # else:
        #     return instance
        super(Dept, self).__get__(instance, owner)

    def __getattr__(self, item):  #
        print('__getattr__: {}'.format(item))
        super(Dept, self).__getattr__(item)

    def __getitem__(self, item):  # “_ getitem_”只适用于所有的“[]”运算符；
        print('__getitem__: {}'.format(item))
        super(Dept, self).__getitem__(item)

    def __getattribute__(self, item):  # “_ getattribute_”只适用于所有的“.”运算符；
        print('__getattribute__: {}'.format(item))
        super(Dept, self).__getattribute__(item)

__get__

__get__将对象作为数据描述符

class Company:
    dept = Dept(20)

c = Company()
c.dept  # __get__: instance:<__main__.test2.<locals>.Company object at 0x1059b07f0> owner:<class '__main__.test2.<locals>.Company'>

__getattribute__

适用 '.' 运算符

d = Dept(15)
d.x  # __getattribute__: x

__getattr__

当 __getattribute__ 找不到触发

d = Dept(15)
d.y  # __getattribute__: y   __getattr__: y

__getitem__

适用 '[]' 运算符

d = Dept(15)
d['x']  # __getitem__: x