One use case for staticmethod

OpenCV_transform.py

class _Transform:
    transform = None
    transargs = ()

    def __call__(self, image):
        """
        Run the transformation and return the tranformed image data
        """
        args = [getattr(self, arg) for arg in self.transargs]
        return self.transform(image, *args)


@attr.s
class GaussianBlur(_Transform):
    transform = staticmethod(cv2.GaussianBlur)
    transargs = ('ksize', 'sigma_x', 'sigma_y')
    ksize = attr.ib()
    @ksize.validator
    def _oddvalued_2tuple(self, attribute, value):
        if len(value) != 2:
            raise ValueError('Must be a sequence of length two')
        a, b = value
        if a % 2 != 1 or b % 2 != 1:
            raise ValueError('Both elements must be odd')

    sigma_x = attr.ib()
    sigma_y = attr.ib(default=0)

staticmethod_validator_test.py

class ValidatorTestCase(unittest.TestCase):
    validator = None

    def assertValid(self, value):
        self.validator(value)

    def assertInvalid(self, value):
        self.assertRaises(ValidationError, self.validator, value)


class FooValidatorTestCase(ValidatorTestCase):
    validator = staticmethod(foovalidator)

    def test_foo_valid(self):
        self.assertValid('foo')

    def test_notfoo_invalid(self):
        self.assertInvalid('notfoo')