Cannot Subclass Error

[czhang03]

I have a dummy base class:

class BaseModel:
    def __init__(self) -> None:
        pass

and I have another class extending this dummy base class:

class DendrogramModel(BaseModel):
    def __init__(self, test_dtm: Optional[pd.DataFrame] = None,
                 test_option: Optional[DendroOption] = None) -> None:
        super().__init__()
        self._test_dtm = test_dtm
        self._test_option = test_option

When I type check, mypy gives me the following error:
error: Class cannot subclass 'BaseModel' (has type 'Any')

I don't know why. Is it because I cannot extend the dummy base class?

[gvanrossum]

The other class is in a different file right? And you have --follow-imports=strict on? You need to tell mypy to check both files.

[czhang03]

Yes, they are in different files.

I don't think follow import allows strict.

Here is the command I used mypy .\lexos\models\dendro_model.py --ignore-missing-imports --strict

[gvanrossum]

Yeah sorry, I meant skip, not strict. But it sounds like the other module can't be found. Where is it?

[czhang03]

I also think that is caused by module not found.

Here is part of my project structure:

Lexos
- lexos/
  - __init__.py
  - models/
     - dendrogram_model.py
     - base_model.py
- test/
  - __ init__.py

Here is the import statement used in dendrogram_model.py

from lexos.models.base_model import BaseModel

according to the mypy documentation, mypy climbs up the __init__.py file, then it will definitely successfully found my project root.

[gvanrossum]

There's no `__init__.py` in models/.

…

On Mon, Oct 30, 2017 at 8:14 PM, chantisnake ***@***.***> wrote: I also think that is caused by module not found. Here is part of my project structure: Lexos - lexos/ - __init__.py - models/ - dendrogram_model.py - base_model.py - test/ - __ init__.py Here is the import statement used in dendrogram_model.py from lexos.models.base_model import BaseModel according to the documentation of mypy documentation <http://mypy.readthedocs.io/en/latest/command_line.html#finding-imports>, mypy climbs up the __init__.py file, then it will definitely successfully found my project root. — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#4180 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ACwrMlYT7wSIRhTywVHGZGg1VmMZvWLRks5sxpB8gaJpZM4QMDjt> .

-- --Guido van Rossum (python.org/~guido)

[czhang03]

uh! how stupid of me...

[gvanrossum]

Not stupid! It takes time to understand how all these things work together. Explaining your problems to someone else is often a helpful debugging technique. (So useful, in fact, that people have called it "rubber duck debugging" -- explain the issue to your rubber ducky and suddenly it becomes clear to you. There's even Wikipedia page for this. :-)

[wabu]

Not stupid!

👍 Having it documented here also helped me resolve the same issue in my code :-)