Merge pull request #339 from python/feature/337-EntryPoint-object

Exploring EntryPoint as a simple object

CHANGES.rst

@@ -1,3 +1,11 @@
+v4.8.0
+======
+
+* #337: Rewrote ``EntryPoint`` as a simple class, still
+  immutable and still with the attributes, but without any
+  expectation for ``namedtuple`` functionality such as
+  ``_asdict``.
+
 v4.7.1
 ======
 

importlib_metadata/__init__.py

@@ -18,7 +18,6 @@
 from ._collections import FreezableDefaultDict, Pair
 from ._compat import (
     NullFinder,
-    PyPy_repr,
     install,
     pypy_partial,
 )
@@ -126,9 +125,7 @@ def valid(line):
         return line and not line.startswith('#')
 
 
-class EntryPoint(
-    PyPy_repr, collections.namedtuple('EntryPointBase', 'name value group')
-):
+class EntryPoint:
     """An entry point as defined by Python packaging conventions.
 
     See `the packaging docs on entry points
@@ -159,6 +156,9 @@ class EntryPoint(
 
     dist: Optional['Distribution'] = None
 
+    def __init__(self, name, value, group):
+        vars(self).update(name=name, value=value, group=group)
+
     def load(self):
         """Load the entry point from its definition. If only a module
         is indicated by the value, return that module. Otherwise,
@@ -185,7 +185,7 @@ def extras(self):
         return list(re.finditer(r'\w+', match.group('extras') or ''))
 
     def _for(self, dist):
-        self.dist = dist
+        vars(self).update(dist=dist)
         return self
 
     def __iter__(self):
@@ -199,16 +199,31 @@ def __iter__(self):
         warnings.warn(msg, DeprecationWarning)
         return iter((self.name, self))
 
-    def __reduce__(self):
-        return (
-            self.__class__,
-            (self.name, self.value, self.group),
-        )
-
     def matches(self, **params):
         attrs = (getattr(self, param) for param in params)
         return all(map(operator.eq, params.values(), attrs))
 
+    def _key(self):
+        return self.name, self.value, self.group
+
+    def __lt__(self, other):
+        return self._key() < other._key()
+
+    def __eq__(self, other):
+        return self._key() == other._key()
+
+    def __setattr__(self, name, value):
+        raise AttributeError("EntryPoint objects are immutable.")
+
+    def __repr__(self):
+        return (
+            f'EntryPoint(name={self.name!r}, value={self.value!r}, '
+            f'group={self.group!r})'
+        )
+
+    def __hash__(self):
+        return hash(self._key())
+
 
 class DeprecatedList(list):
     """
@@ -356,15 +371,11 @@ def groups(self):
     def _from_text_for(cls, text, dist):
         return cls(ep._for(dist) for ep in cls._from_text(text))
 
-    @classmethod
-    def _from_text(cls, text):
-        return itertools.starmap(EntryPoint, cls._parse_groups(text or ''))
-
     @staticmethod
-    def _parse_groups(text):
+    def _from_text(text):
         return (
-            (item.value.name, item.value.value, item.name)
-            for item in Sectioned.section_pairs(text)
+            EntryPoint(name=item.value.name, value=item.value.value, group=item.name)
+            for item in Sectioned.section_pairs(text or '')
         )
 
 

importlib_metadata/_compat.py

@@ -2,7 +2,7 @@
 import platform
 
 
-__all__ = ['install', 'NullFinder', 'PyPy_repr', 'Protocol']
+__all__ = ['install', 'NullFinder', 'Protocol']
 
 
 try:
@@ -66,27 +66,6 @@ def find_spec(*args, **kwargs):
     find_module = find_spec
 
 
-class PyPy_repr:
-    """
-    Override repr for EntryPoint objects on PyPy to avoid __iter__ access.
-    Ref #97, #102.
-    """
-
-    affected = hasattr(sys, 'pypy_version_info')
-
-    def __compat_repr__(self):  # pragma: nocover
-        def make_param(name):
-            value = getattr(self, name)
-            return f'{name}={value!r}'
-
-        params = ', '.join(map(make_param, self._fields))
-        return f'EntryPoint({params})'
-
-    if affected:  # pragma: nocover
-        __repr__ = __compat_repr__
-    del affected
-
-
 def pypy_partial(val):
     """
     Adjust for variable stacklevel on partial under PyPy.

tests/test_main.py

@@ -224,12 +224,20 @@ def test_discovery(self):
 class TestEntryPoints(unittest.TestCase):
     def __init__(self, *args):
         super().__init__(*args)
-        self.ep = importlib_metadata.EntryPoint('name', 'value', 'group')
+        self.ep = importlib_metadata.EntryPoint(
+            name='name', value='value', group='group'
+        )
 
     def test_entry_point_pickleable(self):
         revived = pickle.loads(pickle.dumps(self.ep))
         assert revived == self.ep
 
+    def test_positional_args(self):
+        """
+        Capture legacy (namedtuple) construction, discouraged.
+        """
+        EntryPoint('name', 'value', 'group')
+
     def test_immutable(self):
         """EntryPoints should be immutable"""
         with self.assertRaises(AttributeError):
@@ -264,8 +272,8 @@ def test_sortable(self):
         """
         sorted(
             [
-                EntryPoint('b', 'val', 'group'),
-                EntryPoint('a', 'val', 'group'),
+                EntryPoint(name='b', value='val', group='group'),
+                EntryPoint(name='a', value='val', group='group'),
             ]
         )