| # This file is dual licensed under the terms of the Apache License, Version | |
| # 2.0, and the BSD License. See the LICENSE file in the root of this repository | |
| # for complete details. | |
| from __future__ import absolute_import, division, print_function | |
| import sys | |
| from ._typing import TYPE_CHECKING | |
| if TYPE_CHECKING: # pragma: no cover | |
| from typing import Any, Dict, Tuple, Type | |
| PY2 = sys.version_info[0] == 2 | |
| PY3 = sys.version_info[0] == 3 | |
| # flake8: noqa | |
| if PY3: | |
| string_types = (str,) | |
| else: | |
| string_types = (basestring,) | |
| def with_metaclass(meta, *bases): | |
| # type: (Type[Any], Tuple[Type[Any], ...]) -> Any | |
| """ | |
| Create a base class with a metaclass. | |
| """ | |
| # This requires a bit of explanation: the basic idea is to make a dummy | |
| # metaclass for one level of class instantiation that replaces itself with | |
| # the actual metaclass. | |
| class metaclass(meta): # type: ignore | |
| def __new__(cls, name, this_bases, d): | |
| # type: (Type[Any], str, Tuple[Any], Dict[Any, Any]) -> Any | |
| return meta(name, bases, d) | |
| return type.__new__(metaclass, "temporary_class", (), {}) | |