improve HashableWrapper

satella/coding/structures/hashable_objects.py

-def HashableWrapper(obj):
+from .proxy import Proxy
+
+
+class HashableWrapper(Proxy):
     """
-    A decorator that makes given objects hashable by their id.
+    A class that makes given objects hashable by their id.
+
+    Note that this class will return a proxy to the object, and not the object itself.
 
     Use like:
 
@@ -12,6 +17,6 @@ def HashableWrapper(obj):
     >>> a.a = 4
     >>> assert a.a == 4
     """
-    if not hasattr(obj, '__hash__'):
-        obj.__hash__ = lambda self: hash(id(self))
-    return obj
+
+    def __hash__(self):
+        return hash(id(self))

satella/coding/structures/proxy.py

@@ -42,7 +42,7 @@ class Proxy(tp.Generic[T]):
         return getattr(self.__obj, item)
 
     def __delattr__(self, item):
-        del self.__obj[item]
+        delattr(self.__obj, item)
 
     def __int__(self):
         return int(self.__obj)

tests/test_coding/test_structures.py

@@ -99,6 +99,9 @@ class TestMisc(unittest.TestCase):
             def __call__(self, *args, **kwargs):
                 return 5
 
+            def __hash__(self):
+                raise TypeError()
+
         nh = NotHashable(5)
         nw = HashableWrapper(nh)
         self.assertEqual(nw.a, 5)