.github/workflows/build.yaml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        python_version: ['3.9','3.10','3.11','3.13']
+        python_version: ['3.8', '3.9','3.10','3.11']
         os: [ubuntu-latest]
 
     steps:

settngs/__init__.py

@@ -10,13 +10,10 @@ import re
 import sys
 import typing
 import warnings
-from argparse import BooleanOptionalAction
 from argparse import Namespace
 from collections import defaultdict
 from collections.abc import Sequence
 from collections.abc import Set
-from enum import Enum
-from types import GenericAlias as types_GenericAlias
 from typing import Any
 from typing import Callable
 from typing import cast
@@ -41,6 +38,72 @@ else:  # pragma: no cover
     from typing import NamedTuple
 
 
+if sys.version_info < (3, 9):  # pragma: no cover
+    from typing import List
+    from typing import _GenericAlias as types_GenericAlias
+
+    def removeprefix(self: str, prefix: str, /) -> str:
+        if self.startswith(prefix):
+            return self[len(prefix):]
+        else:
+            return self[:]
+
+    def get_typing_type(t: type) -> type:
+        if t.__module__ == 'builtins':
+            if t is NoneType:
+                return None
+            return getattr(typing, t.__name__.title(), t)
+        return t
+
+    class BooleanOptionalAction(argparse.Action):
+        def __init__(
+            self,
+            option_strings,
+            dest,
+            default=None,
+            type=None,  # noqa: A002
+            choices=None,
+            required=False,
+            help=None,  # noqa: A002
+            metavar=None,
+        ):
+
+            _option_strings = []
+            for option_string in option_strings:
+                _option_strings.append(option_string)
+
+                if option_string.startswith('--'):
+                    option_string = '--no-' + option_string[2:]
+                    _option_strings.append(option_string)
+
+            if help is not None and default is not None and default is not argparse.SUPPRESS:
+                help += ' (default: %(default)s)'
+
+            super().__init__(
+                option_strings=_option_strings,
+                dest=dest,
+                nargs=0,
+                default=default,
+                type=type,
+                choices=choices,
+                required=required,
+                help=help,
+                metavar=metavar,
+            )
+
+        def __call__(self, parser, namespace, values, option_string=None):  # pragma: no cover dead: disable
+            if option_string in self.option_strings:
+                setattr(namespace, self.dest, not option_string.startswith('--no-'))
+else:  # pragma: no cover
+    List = list
+    from types import GenericAlias as types_GenericAlias
+    from argparse import BooleanOptionalAction
+    removeprefix = str.removeprefix
+
+    def get_typing_type(t: type) -> type | None:
+        return None if t is NoneType else t
+
+
 def _isnamedtupleinstance(x: Any) -> bool:  # pragma: no cover
     t = type(x)
     b = t.__bases__
@@ -183,14 +246,15 @@ class Setting:
             if isinstance(list_type, types_GenericAlias) and issubclass(list_type.__origin__, Collection):
                 return list_type, self.default is None
 
-            if list_type is NoneType:
-                list_type = None
-            if list_type is None and self.default is not None:
-                list_type = type(self.default)
+            # Ensure that generic aliases work for python 3.8
+            if list_type is not None:
+                list_type = get_typing_type(list_type)
+            else:
+                list_type = get_typing_type(type(self.default))
 
             # Default to a list if we don't know what type of collection this is
-            if list_type is None or not issubclass(list_type, Collection) or issubclass(list_type, Enum):
-                list_type = list
+            if list_type is None or not issubclass(list_type, Collection):
+                list_type = List
 
             # Get the item type (int) in list[int]
             it = get_item_type(self.default)
@@ -198,7 +262,7 @@ class Setting:
                 it = self.type
 
             if it is self.__no_type:
-                return self._process_type() or list[str], self.default is None
+                return self._process_type() or List[str], self.default is None
 
             # Try to get the generic alias for this type
             if it is not None:
@@ -230,7 +294,7 @@ class Setting:
             'store_const': (type(self.const), default_is_none),
             'count': (int, default_is_none),
             'extend': self._guess_collection(),
-            'append_const': (list[type(self.const)], default_is_none),  # type: ignore[misc]
+            'append_const': (List[type(self.const)], default_is_none),  # type: ignore[misc]
             'help': (None, default_is_none),
             'version': (None, default_is_none),
         }
@@ -268,7 +332,7 @@ class Setting:
 
     def _guess_type(self) -> tuple[type | str | None, bool]:
         if self.action == 'append':
-            return list[self._guess_type_internal()[0]], self.default is None  # type: ignore[misc]
+            return List[self._guess_type_internal()[0]], self.default is None  # type: ignore[misc]
         return self._guess_type_internal()
 
     def get_dest(self, prefix: str, names: Sequence[str], dest: str | None) -> tuple[str, str, str, bool]:
@@ -485,7 +549,7 @@ def get_options(config: Config[T], group: str) -> dict[str, Any]:
                 if name in internal_names:
                     values[internal_names[name].dest] = value
                 else:
-                    values[name.removeprefix(f'{group}').lstrip('_')] = value
+                    values[removeprefix(name, f'{group}').lstrip('_')] = value
     return values
 
 

setup.cfg

@@ -19,7 +19,7 @@ classifiers =
 packages = find:
 install_requires =
     typing-extensions>=4.3.0;python_version < '3.11'
-python_requires = >=3.9
+python_requires = >=3.8
 include_package_data = True
 
 [options.packages.find]
@@ -31,7 +31,7 @@ exclude =
 settngs = py.typed
 
 [tox:tox]
-envlist = py3.9,py3.10,py3.11,py3.12,py3.13,pypy3
+envlist = py3.8,py3.9,py3.10,py3.11,py3.12,pypy3
 
 [testenv]
 deps = -rrequirements-dev.txt