Python interaction between __setattr__ and self.__dict__ -

if make class instance this

class myclass(object):     pass x = myclass() 

i can set attributes on x follows:

x.myattr = 1 or x.__setattr__('myattr', 1)

however, if make dict

d = {} 

i cannot set attributes on it. example, if this

d.__setattr__('myattr', 1) 

i error " 'dict' object has no attribute 'myattr' " same thing happens if try

d.myattr = 1 

i have noticed in case of x.myattr = 1 happens that

x.__dict__ 

gets updated new key, must that

d.__setattr__ 

doesn't work because d doesn't have

d.__dict__ 

simply because d is dict. appreciate if thoroughly explain what's going on here.

do python objects have .__dict__?

why attempt @ calling d.__setattr__ result in error saying attribute doesn't exist?

is there specific heirarchy of built-in types should know about? simple reference appreciated.

python 2.6.4

windows xp pro x64 sp2

a dict instance doesn't have __dict__ attribute, can't assign attributes on it. of python's built-in classes (which written in c , define attributes differently) don't. if subclass dict, subclass have __dict__ attribute , can add attributes instances of subclass.