Deprecate dict construction from EntryPoint items.

Author: jaraco

importlib_metadata/__init__.py

@@ -7,6 +7,7 @@
 import email
 import pathlib
 import operator
+import warnings
 import functools
 import itertools
 import posixpath
@@ -139,11 +140,12 @@ def _for(self, dist):
     def __iter__(self):
         """
         Supply iter so one may construct dicts of EntryPoints by name.
-
-        >>> eps = [EntryPoint('a', 'b', 'c'), EntryPoint('d', 'e', 'f')]
-        >>> dict(eps)['a']
-        EntryPoint(name='a', value='b', group='c')
         """
+        msg = (
+            "Construction of dict of EntryPoints is deprecated in "
+            "favor of EntryPoints."
+        )
+        warnings.warn(msg, DeprecationWarning)
         return iter((self.name, self))
 
     def __reduce__(self):

tests/test_api.py

@@ -1,6 +1,7 @@
 import re
 import textwrap
 import unittest
+import warnings
 
 from . import fixtures
 from importlib_metadata import (
@@ -88,10 +89,17 @@ def test_entry_points_dict_construction(self):
         allowed casting those lists into maps by name using ``dict()``.
         Capture this now deprecated use-case.
         """
-        eps = dict(entry_points()['entries'])
+        with warnings.catch_warnings(record=True) as caught:
+            eps = dict(entry_points()['entries'])
+
         assert 'main' in eps
         assert eps['main'] == entry_points()['entries']['main']
 
+        # check warning
+        expected = next(iter(caught))
+        assert expected.category is DeprecationWarning
+        assert "Construction of dict of EntryPoints is deprecated" in str(expected)
+
     def test_metadata_for_this_package(self):
         md = metadata('egginfo-pkg')
         assert md['author'] == 'Steven Ma'