Member is not assignable error when accessing a module member

[gilbsgilbs]

Hi,

This issue seems close to the one that was fixed in this PR.

• Are you reporting a bug, or opening a feature request?

I'm reporting a bug.

• Please insert below the code you are checking with mypy,
  or a mock-up repro if the source is private. We would appreciate
  if you try to simplify your case to a minimal repro.

import functools

class Foo:
    bar = functools

foo = Foo()
foo.bar  # error: Member "bar" is not assignable

• What is the actual behavior/output?

test.py:7: error: Member "bar" is not assignable

• What is the behavior/output you expect?

No Error. I'm just accessing, not mutating.

• What are the versions of mypy and Python you are using?
  Do you see the same issue after installing mypy from Git master?

$ mypy --version
mypy 0.620

Same error on master.

• What are the mypy flags you are using? (For example --strict-optional)

No flags. Just raw mypy test.py

If you need any further information, please let me know.
Thank you in advance.

[ilevkivskyi]

Thanks for reporting!

This particular error is probably easy to fix, but then the best type we can give to foo.bar is types.ModuleType. Supporting things like foo.bar.reduce may be much harder.

[gilbsgilbs]

Many thanks @ilevkivskyi for your insanely quick reply and tagging.

This particular error is probably easy to fix, but then the best type we can give to foo.bar is types.ModuleType. Supporting things like foo.bar.reduce may be much harder.

You know the implications way better than me, but just to be sure I understand, do you mean that:

import functools

class Foo:
    bar = functools.reduce

foo = Foo()
foo.bar

• foo.bar will loose type safety?
• foo.bar line will raise an error, just as reproduced in this issue?

Also, does this mean that, if in my first post example I write r = foo.bar.reduce, I will loose type safety on r?

Anyways, this would probably be preferable than raising an error since the use-case sounds 100% legitimate to me, wouldn't it?

[ilevkivskyi]

do you mean that...

No, I meant exactly your code in the original post.