Attribute Error using `__setattr__` on Windows

When running the following code, it works fine on Python 3.6 on Ubuntu 18.02 but not Windows 10.

>>> import wrapt
>>> a = wrapt.ObjectProxy(None)
>>> a.__setattr__('__dict__', {})

It errors when trying to set the attribute:

elif hasattr(type(self), name):
>           object.__setattr__(self, name, value)
E           AttributeError: can't set attribute

[GrahamDumpleton]

The original problem and difference you saw is that __dict__ can only be changed on a Python class implemented as Python code. The ObjectProxy can be pure Python code, or C code depending on whether compiler was present so that C code implementation could be installed. Trying to update it when it was implemented as C code will fail.

[cdgriffith]

Okay I think I have a clearer idea now what I need to do. (I am new to wrapt and this code was recently accepted into a project I own so trying to nail down how best for it to work. Sorry for any confusion!) The code was trying to set __dict__ even when an object type that could be wrapped did not have that property.

Thank you so much for the quick guidance!

Just as an aside, It’s actually possible to set __dict__ to dict or any dict subclass.

from box import Box  # Box is a subclass of dict

class A:
    pass

h = A()

print(h.__dict__)
# {}
h.__dict__ = []
# Traceback (most recent call last):
#  File "<input>", line 1, in <module>
# TypeError: __dict__ must be set to a dictionary, not a 'list'
h.__dict__ = Box()
print(h.__dict__)
# <Box: {}>