Issue #22609: Constructor and the update method of collections.UserDict now

accept the self keyword argument.

Lib/UserDict.py

 """A more or less complete user-defined wrapper around dictionary objects."""
 
 class UserDict:
-    def __init__(self, dict=None, **kwargs):
+    def __init__(*args, **kwargs):
+        if not args:
+            raise TypeError("descriptor '__init__' of 'UserDict' object "
+                            "needs an argument")
+        self = args[0]
+        args = args[1:]
+        if len(args) > 1:
+            raise TypeError('expected at most 1 arguments, got %d' % len(args))
+        if args:
+            dict = args[0]
+        elif 'dict' in kwargs:
+            dict = kwargs.pop('dict')
+            import warnings
+            warnings.warn("Passing 'dict' as keyword argument is "
+                          "deprecated", PendingDeprecationWarning,
+                          stacklevel=2)
+        else:
+            dict = None
         self.data = {}
         if dict is not None:
             self.update(dict)
@@ -43,7 +60,23 @@ class UserDict:
     def itervalues(self): return self.data.itervalues()
     def values(self): return self.data.values()
     def has_key(self, key): return key in self.data
-    def update(self, dict=None, **kwargs):
+    def update(*args, **kwargs):
+        if not args:
+            raise TypeError("descriptor 'update' of 'UserDict' object "
+                            "needs an argument")
+        self = args[0]
+        args = args[1:]
+        if len(args) > 1:
+            raise TypeError('expected at most 1 arguments, got %d' % len(args))
+        if args:
+            dict = args[0]
+        elif 'dict' in kwargs:
+            dict = kwargs.pop('dict')
+            import warnings
+            warnings.warn("Passing 'dict' as keyword argument is deprecated",
+                          PendingDeprecationWarning, stacklevel=2)
+        else:
+            dict = None
         if dict is None:
             pass
         elif isinstance(dict, UserDict):

Lib/test/test_userdict.py

@@ -2,6 +2,7 @@
 
 from test import test_support, mapping_tests
 import UserDict
+import warnings
 
 d0 = {}
 d1 = {"one": 1}
@@ -29,7 +30,9 @@ class UserDictTest(mapping_tests.TestHashMappingProtocol):
         self.assertEqual(UserDict.UserDict(one=1, two=2), d2)
         # item sequence constructor
         self.assertEqual(UserDict.UserDict([('one',1), ('two',2)]), d2)
-        self.assertEqual(UserDict.UserDict(dict=[('one',1), ('two',2)]), d2)
+        with test_support.check_warnings((".*'dict'.*",
+                                          PendingDeprecationWarning)):
+            self.assertEqual(UserDict.UserDict(dict=[('one',1), ('two',2)]), d2)
         # both together
         self.assertEqual(UserDict.UserDict([('one',1), ('two',2)], two=3, three=5), d3)
 
@@ -148,6 +151,36 @@ class UserDictTest(mapping_tests.TestHashMappingProtocol):
         self.assertEqual(t.popitem(), ("x", 42))
         self.assertRaises(KeyError, t.popitem)
 
+    def test_init(self):
+        for kw in 'self', 'other', 'iterable':
+            self.assertEqual(list(UserDict.UserDict(**{kw: 42}).items()),
+                             [(kw, 42)])
+        self.assertEqual(list(UserDict.UserDict({}, dict=42).items()),
+                         [('dict', 42)])
+        self.assertEqual(list(UserDict.UserDict({}, dict=None).items()),
+                         [('dict', None)])
+        with test_support.check_warnings((".*'dict'.*",
+                                          PendingDeprecationWarning)):
+            self.assertEqual(list(UserDict.UserDict(dict={'a': 42}).items()),
+                             [('a', 42)])
+        self.assertRaises(TypeError, UserDict.UserDict, 42)
+        self.assertRaises(TypeError, UserDict.UserDict, (), ())
+        self.assertRaises(TypeError, UserDict.UserDict.__init__)
+
+    def test_update(self):
+        for kw in 'self', 'other', 'iterable':
+            d = UserDict.UserDict()
+            d.update(**{kw: 42})
+            self.assertEqual(list(d.items()), [(kw, 42)])
+        d = UserDict.UserDict()
+        with test_support.check_warnings((".*'dict'.*",
+                                          PendingDeprecationWarning)):
+            d.update(dict={'a': 42})
+        self.assertEqual(list(d.items()), [('a', 42)])
+        self.assertRaises(TypeError, UserDict.UserDict().update, 42)
+        self.assertRaises(TypeError, UserDict.UserDict().update, {}, {})
+        self.assertRaises(TypeError, UserDict.UserDict.update)
+
     def test_missing(self):
         # Make sure UserDict doesn't have a __missing__ method
         self.assertEqual(hasattr(UserDict, "__missing__"), False)

Misc/NEWS

@@ -37,6 +37,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #22609: Constructor and the update method of collections.UserDict now
+  accept the self keyword argument.
+
 - Issue #25203: Failed readline.set_completer_delims() no longer left the
   module in inconsistent state.