Restore remaining changes.

Author: jaraco

Lib/importlib/metadata/__init__.py

@@ -136,8 +136,6 @@ class _EntryPointMatch(types.SimpleNamespace):
     extras: str
 
 
-from typing import Optional, List, cast, Match
-
 class EntryPoint:
     """An entry point as defined by Python packaging conventions.
 
@@ -204,38 +202,44 @@ class EntryPoint:
     value: str
     group: str
 
-    dist: Optional[Distribution] = None
+    dist: Distribution | None = None
 
     def __init__(self, name: str, value: str, group: str) -> None:
         vars(self).update(name=name, value=value, group=group)
+        self.module
 
     def load(self) -> Any:
         """Load the entry point from its definition. If only a module
         is indicated by the value, return that module. Otherwise,
         return the named object.
         """
-        match = cast(Match, self.pattern.match(self.value))
-        module = import_module(match.group('module'))
-        attrs = filter(None, (match.group('attr') or '').split('.'))
+        module = import_module(self.module)
+        attrs = filter(None, (self.attr or '').split('.'))
         return functools.reduce(getattr, attrs, module)
 
     @property
     def module(self) -> str:
-        match = self.pattern.match(self.value)
-        assert match is not None
-        return match.group('module')
+        return self._match.module
 
     @property
     def attr(self) -> str:
-        match = self.pattern.match(self.value)
-        assert match is not None
-        return match.group('attr')
+        return self._match.attr
 
     @property
-    def extras(self) -> List[str]:
+    def extras(self) -> list[str]:
+        return re.findall(r'\w+', self._match.extras or '')
+
+    @functools.cached_property
+    def _match(self) -> _EntryPointMatch:
         match = self.pattern.match(self.value)
-        assert match is not None
-        return re.findall(r'\w+', match.group('extras') or '')
+        if not match:
+            raise ValueError(
+                'Invalid object reference. '
+                'See https://packaging.python.org'
+                '/en/latest/specifications/entry-points/#data-model',
+                self.value,
+            )
+        return _EntryPointMatch(**match.groupdict())
 
     def _for(self, dist):
         vars(self).update(dist=dist)
@@ -261,9 +265,26 @@ def matches(self, **params):
         >>> ep.matches(attr='bong')
         True
         """
+        self._disallow_dist(params)
         attrs = (getattr(self, param) for param in params)
         return all(map(operator.eq, params.values(), attrs))
 
+    @staticmethod
+    def _disallow_dist(params):
+        """
+        Querying by dist is not allowed (dist objects are not comparable).
+        >>> EntryPoint(name='fan', value='fav', group='fag').matches(dist='foo')
+        Traceback (most recent call last):
+        ...
+        ValueError: "dist" is not suitable for matching...
+        """
+        if "dist" in params:
+            raise ValueError(
+                '"dist" is not suitable for matching. '
+                "Instead, use Distribution.entry_points.select() on a "
+                "located distribution."
+            )
+
     def _key(self):
         return self.name, self.value, self.group
 
@@ -1094,7 +1115,7 @@ def packages_distributions() -> Mapping[str, list[str]]:
     pkg_to_dist = collections.defaultdict(list)
     for dist in distributions():
         for pkg in _top_level_declared(dist) or _top_level_inferred(dist):
-            pkg_to_dist[pkg].append(dist.metadata['Name'])
+            pkg_to_dist[pkg].append(md_none(dist.metadata)['Name'])
     return dict(pkg_to_dist)
 
 

Lib/test/test_importlib/metadata/test_main.py

@@ -157,7 +157,6 @@ def test_valid_dists_preferred(self):
         dist = Distribution.from_name('foo')
         assert dist.version == "1.0"
 
-    @unittest.skip("Functionality disabled")
     def test_missing_metadata(self):
         """
         Dists with a missing metadata file should return None.