Handle missing pkg_resources gracefully

CHANGELOG.md

@@ -1,5 +1,7 @@
 # Changelog
 
+- 2025-11-05:
+  Make the `pkg_resources.declare_namespace` patch work even if there's no longer a real `pkg_resources` module.
 - 2025-11-05:
   Fix handling of namespaces that have an `__init__.py` installed.
   Now we read the namespaces from `*.dist-info/namespace_packages.txt` instead of looking for modules that were loaded with NamespaceLoader.

src/horse_with_no_namespace/__about__.py

@@ -1,4 +1,4 @@
 # SPDX-FileCopyrightText: 2025 David Glick <[email protected]>
 #
 # SPDX-License-Identifier: MIT
-__version__ = "20251105.0"
+__version__ = "20251105.1"

src/horse_with_no_namespace/pkg_resources.py

@@ -47,10 +47,21 @@ def _lazy_load_pkg_resources():
     # This is called when something from pkg_resources is accessed.
     # We import it here to avoid importing it at the top of the file,
     # which would cause a circular import.
-    del sys.modules["pkg_resources"]
-    import pkg_resources
-
-    pkg_resources.declare_namespace = declare_namespace
+    # But let's be careful in case the real pkg_resources isn't available...
+    existing_pkg_resources = sys.modules["pkg_resources"]
+    try:
+        del sys.modules["pkg_resources"]
+        import pkg_resources
+    except ModuleNotFoundError:
+        # There is no actual pkg_resources module
+        # (maybe it's a new version of setuptools that removed it).
+        # So keep this stub and stop trying to replace it.
+        pkg_resources = sys.modules["pkg_resources"] = existing_pkg_resources
+        del globals()["__getattr__"]
+        del globals()["__dir__"]
+    else:
+        # Patch the real pkg_resources to use our declare_namespace function.
+        pkg_resources.declare_namespace = declare_namespace
     _pkg_resources = pkg_resources