def __call__(self, inst, attr, value):
        """
        We use a callable class to be able to change the ``__repr__``.
        """
        if len(value) > self.max_length:
            raise ValueError(
                "Length of '{name}' must be <= {max}: {len}".format(
                    name=attr.name, max=self.max_length, len=len(value)
                )
            )

        We use a callable class to be able to change the ``__repr__``.
        
product/gradle-plugin/src/main/python/attr/validators.py