Switch from SelectableGroups to hasattr for importlib.metadata branching (#61) (#62)

`SelectableGroups` is no longer in python 3.12 and the original reason
for this design was the lack of support for `hasattr` for mypy, which
has since been resolved.

Author: adrianeboyd

catalogue/__init__.py

@@ -7,15 +7,6 @@
 except ImportError:
     from . import _importlib_metadata as importlib_metadata  # type: ignore
 
-try:  # Python 3.10
-    from importlib.metadata import SelectableGroups  # type: ignore
-except ImportError:
-
-    class _NotImplemented:
-        pass
-
-    SelectableGroups = _NotImplemented  # type: ignore
-
 # Only ever call this once for performance reasons
 AVAILABLE_ENTRY_POINTS = importlib_metadata.entry_points()  # type: ignore
 
@@ -148,7 +139,7 @@ def get_entry_point(self, name: str, default: Optional[Any] = None) -> Any:
         return default
 
     def _get_entry_points(self) -> List[importlib_metadata.EntryPoint]:
-        if isinstance(AVAILABLE_ENTRY_POINTS, SelectableGroups):
+        if hasattr(AVAILABLE_ENTRY_POINTS, "select"):
             return AVAILABLE_ENTRY_POINTS.select(group=self.entry_point_namespace)
         else:  # dict
             return AVAILABLE_ENTRY_POINTS.get(self.entry_point_namespace, [])

requirements.txt

@@ -1,4 +1,4 @@
 zipp>=0.5; python_version < "3.8"
 typing-extensions>=3.6.4; python_version < "3.8"
 pytest>=4.6.5
-mypy>=0.991,<1.1.0
+mypy>=0.991,<1.1.0