python 3.7 type compatibility

Author: wolph

python_utils/containers.py

@@ -22,7 +22,7 @@
     '_typeshed.SupportsKeysAndGetItem[KT, VT]',
 ]
 
-OnDuplicate = types.Literal['raise', 'ignore']
+OnDuplicate: types.Literal['raise', 'ignore']
 
 
 class CastedDictBase(types.Dict[KT, VT], abc.ABC):
@@ -208,6 +208,7 @@ class UniqueList(types.List[VT]):
     ...
     ValueError: Duplicate value: 4
     '''
+
     _set: set[VT]
 
     def __init__(self, *args: VT, on_duplicate: OnDuplicate = 'ignore'):
@@ -275,9 +276,8 @@ def __setitem__(self, indices, values) -> None:
             super().__setitem__(indices, values)
 
     def __delitem__(
-        self,
-        index: types.Union[types.SupportsIndex, slice]
-        ) -> None:
+        self, index: types.Union[types.SupportsIndex, slice]
+    ) -> None:
         if isinstance(index, slice):
             for value in self[index]:
                 self._set.remove(value)

python_utils/types.py

@@ -5,6 +5,11 @@
 # import * does not import Pattern
 from typing import Pattern
 
+try:
+    from typing import Literal, SupportsIndex  # type: ignore
+except ImportError:
+    from typing_extensions import Literal, SupportsIndex
+
 # Quickhand for optional because it gets so much use. If only Python had
 # support for an optional type shorthand such as `SomeType?` instead of
 # `Optional[SomeType]`.
@@ -33,7 +38,9 @@
     None,
 ]
 
-assert Pattern
+assert Pattern  # type: ignore
+assert Literal
+assert SupportsIndex
 
 __all__ = [
     'OptionalScope',
@@ -52,6 +59,7 @@
     'ForwardRef',
     'Generic',
     'Literal',
+    'SupportsIndex',
     'Optional',
     'ParamSpec',
     'Protocol',

setup.py

@@ -14,6 +14,8 @@
 else:
     long_description = 'See http://pypi.python.org/pypi/python-utils/'
 
+install_requires = []
+
 if __name__ == '__main__':
     setuptools.setup(
         python_requires='>3.6.0',
@@ -29,6 +31,7 @@
         ),
         package_data={'python_utils': ['py.typed']},
         long_description=long_description,
+        install_requires=['typing_extensions;python_version<"3.8"'],
         tests_require=['pytest'],
         extras_require={
             'loguru': [