Class cannot subclass 'QObject' (has type 'Any') using mypy

Question

I have a class that subclasses QObject. Everyting works fine but when I run mypy on it I get the error:

"error: Class cannot subclass 'QObject' (has type 'Any')"

At the moment I am totally stuck. I Have been reading the mypy docs but couldn't find where the error was.

Here the code:

from PyQt5.QtCore import QObject

class ServiceLocator(QObject):

    def __init__(self) -> None:
        super().__init__()
        ...

Cheers.

Never used mypy. But the -> looks wonky. An initializer doesn’t return anything. — deets, Apr 17 '18 at 22:16
Sorry but, You are wrong. __ init __ is required to return None. In fact it does, but implicitly in this case. — Notbad, Apr 17 '18 at 22:20
Have a look at this issue that appears to be the same as yours: https://github.com/python/mypy/issues/4180 and is related to accessing modules in other files. Guido says, "You need to tell mypy to check both files." — Lindsay Ward, Apr 17 '18 at 23:23
This helped me. Did not solved my problem but made me achieve a "solution" — Notbad, Apr 18 '18 at 10:30

score 13 · Accepted Answer · answered Apr 23 '18 at 22:48

This error occurs when mypy doesn't have type information for a class (in your case due to a lack of stubs) and you have --disallow-subclassing-any turned on. You can either disable this flag, add typing information, or, as you pointed out, put a # type: ignore to silence the error.

score 7 · Answer 2 · edited Jun 28 '19 at 17:48

7

In order to leave a record on how I get around this I will answer my own question.

As the previous comment suggests, the error arise because mypy doesn't have information about QObject. I tried to add the .pyi files to mypy in the third-party folder from here or you can try building from sources PyQt5.

Everything worked but a lot of other errors arose so I finally decided to use:

#type: ignore

on this lines and get rid of the error until type hinting is better supported for this lib.

Cheers.

edited Jun 28 '19 at 17:48

Marcin Możejko

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answered Apr 18 '18 at 10:34

Notbad

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"until type hinting is better supported for this lib" - if you did own the lib, how would you have fixed it? – marengaz Apr 30 '21 at 21:12

score 0 · Answer 3 · answered Dec 20 '22 at 14:53

0

This is happening to me in a library that was fully typed. The problem was that these objects were not defined as public in the __all__ variable inside of the library (doc)

answered Dec 20 '22 at 14:53

Francisco Rodeño Sanchez

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Class cannot subclass 'QObject' (has type 'Any') using mypy

3 Answers3

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