python - How can I replace a class @property's len(..) return with a custom __len__() procedure? -

when class defined (ex. class myclass), possible replace returns len(my_class_instance) using def __len__(self).

• how can apply custom class @property in below scenario?

  class carwash(object):     def __init__(self):         self._queue = [1, 2, 3]      @property     def queue(self):         return self._queue 

when len(car_wash.queue) called, don't want list's len returned replace custom __len__ procedure, since want query db first.

how can this?

if don't want list.__len__ called, don't return list:

def carqueue(list):     def __len__(self):         return something_dubious()     # if you're going override len, make sure overide `__iter__`     # , `__getitem__`  class carwash(object):     def __init__(self):         self._queue = carqueue([1, 2, 3])      @property     def queue(self):         return self._queue