Add support for SimpleNamespace

[DanielShaulov]

The following code gives errors:

from types import SimpleNamespace
ns = SimpleNamespace()
ns.a = 5
print(ns.a/2)

There are two ways to make this work:

• Treat it like a Dict[str, Any]. Allow all assignments and treat all reads as if they return Any.
• Track the first assignment and then treat it as that type. Reading before assignment is an error.

I haven't seen any of mypy's code, but the first sounds simpler. Although there should already be something similar to the second option for module level variables.

[JukkaL]

Hmm I've never used SimpleNamespace. However, it doesn't look to be much like Dict[...]. A potential way to define it in a stub is like this:

_base = None  # type: Any
class SimpleNamespace(_base): ...

This means that mypy would basically assume that it can have an arbitrary, unknown set of attributes, due to the Any base class.

The change would have to go to stubs which live in the typeshed repo. Would you mind creating an issue there (https://github.com/python/typeshed/issues)?

[DanielShaulov]

Hi, Thanks.
This works exactly like I meant in my first point.
A few questions:

• can I just directly inherit in the stub? (seems like it works)

class SimpleNamespace(Any): ...

• Is there any way to make it work like in my second option? tracking the assignments and checking the types?

[gvanrossum]

Closing this, as it's a typeshed issue.