Missing argument false positive

[lovemyliwu]

the example py:

class classonlymethod(classmethod):
    def __get__(self, instance, cls=None):
        if instance is not None:
            raise AttributeError("This method is available only on the class, not on instances.")
        return super(classonlymethod, self).__get__(instance, cls)

class Test:
    @classonlymethod
    def say(cls):
        print('hello')

Test.say()

the classonlymethod decorator copy from from django.utils.decorators import classonlymethod

the ouput:

No watchman binary found. 
To enable pyre incremental, you can install watchman: https://facebook.github.io/watchman/docs/install.html
Defaulting to non-incremental check.
 ƛ Found 1 type error!
classonly.py:12:0 Missing argument [20]: Call `classonly.Test.say` expects argument `cls`.

[MaggieMoss]

@lovemyliwu it should work if you use the @classmethod decorator. Is there a specific reason you wanted to use the classonlymethod decorator instead?

[bigfootjon]

I've got the same problem, I use the @classonlymethod annotation to make sure that callers have to use the full class name instead of self. It helps reason about what the method might do.

If I could get some pointers on how to make the change I'd be happy to submit a PR? From my naive perspective it seems like it's just a matter of adding @classonlymethod to definition for @classmethod and adding a restriction that it can only be used on the class, not an instance.

[mrkmndz]

Im currently working on supporting class-based decorators like classonlymethod, this hopefully should be in the next release

On Thu, May 28, 2020 at 8:34 PM Jon Janzen [email protected] wrote:

I've got the same problem, I use the @classonlymethod annotation to make sure that callers have to use the full class name instead of self. It helps reason about what the method might do.

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