python在__new__函数中用pickle做cache， 结果导致无限递归？

Question

如题所述， 下述代码会导致无限递归。 这是对odoo中registry的简化， new 方法里面的东西是已经有的， 请问各位如何解决

import pickle

class Cache:
    def __init__(self):
        self.d = {}

    def __setitem__(self, obj, val):
        self.d[obj] = pickle.dumps(val)

    def __getitem__(self, obj):
        return pickle.loads(self.d[obj])

class Car:

    cache = Cache()

    def __reduce__(self):
        return self.__class__, (self.name,)

    def __new__(cls, name):
        try:
            return cls.cache[name]
        except KeyError:
            return cls.new(name)

    @classmethod
    def new(cls, name):
        car = object.__new__(cls)
        car.init(name)
        cls.cache[name] = car
        return car

    def init(self, name):
        self.name = name

    def __repr__(self):
        return self.name


a = Car('audi')
b = Car('audi')

Answer 1

object.__new__ 會觸發 Car 的 __new__。所以應該將 new 改爲：

@classmethod
def new(cls, name):
    cls.init(cls, name)
    cls.cache[name] = cls
    return cls