Should treat collections.Mapping keys/values like dict.keys/values

[wosc]

Basically something like

--- checker.py~	2019-04-23 14:47:56.000000000 +0200
+++ checker.py	2020-01-16 15:02:56.000000000 +0100
@@ -757,6 +757,18 @@
     _basic_types[type({}.keys())] = NoProxy
     _basic_types[type({}.items())] = NoProxy

+     class DummyMapping(collections.abc.Mapping):
+
+        def __getitem__(self, key):
+            raise KeyError(key)
+        def __iter__(self):
+            return iter(())
+        def __len__(self):
+            return 0
+    mydict = DummyMapping()
+    _basic_types[type(mydict.keys())] = NoProxy
+    _basic_types[type(mydict.values())] = NoProxy
+    _basic_types[type(mydict.items())] = NoProxy
+
 try:
     import pytz
 except ImportError:  # pragma: no cover

[jamadden]

One possible issue with that: The dict view types are implemented in C (in CPython), and are truly immutable. But the Mapping view types (collections.abc.KeysView, collections.abc.ValuesView and collections.abc.ItemsView) are implemented in Python, and have an easily accessible _mapping attribute. With no proxy around them, the original mapping could be accessed and even mutated.

UPDATED to add: Maybe having interfaces for them (zopefoundation/zope.interface#175) will make writing normal security definitions easier.