python - Making __dict__ A Property -

why work:

class bunch(dict):      def __init__(self, *args, **kwargs):         super(bunch, self).__init__(*args, **kwargs)         self.__dict__ = self  b = bunch() b["a"] = 1 print(b.a) 

albeit circular reference:

import sys print(sys.getrefcount(b)) # ref count 3 when 2 

but not this:

class bunch(dict):      @property     def __dict__(self):         return self  b = bunch() b["a"] = 1 b.a  # raises attributeerror 

while __dict__ attribute outward appearances, there's special behavior being implemented behind scenes bypassing descriptor logic created property.

the default __dict__ attribute is property. (it's not literally property, it's implemented through descriptor protocol, property.)

when set self.__dict__ = self, goes through __dict__ descriptor's __set__ method , replaces dict used instance attributes.

however, python doesn't use __dict__ descriptor find instance dict when performing attribute operations; uses different internal mechanism. thus, creating own __dict__ descriptor doesn't affect attribute lookup mechanism b.a in second example.