added class rebasing function

evil.py

@@ -44,3 +44,50 @@ def pin(loc, *skip):
             )
         }
     )
+
+
+def rebase(obj, want, dont=(), name=None, ns=None):
+    if isinstance(obj, type):
+        cls = obj
+        obj = None
+    else:
+        assert obj is not None
+        cls = type(obj)
+
+    if not isinstance(want, (list, tuple)):
+        want = (want,)
+    if not isinstance(dont, (list, tuple)):
+        dont = (dont,)
+    assert want or dont
+
+    want = tuple(w for w in want if w not in cls.__bases__)
+
+    if name is None:
+        name = cls.__name__
+        for d in dont:
+            name = name.replace(d.__name__, "", 1)
+        for w in want:
+            if w.__name__ not in name:
+                name += w.__name__
+
+    bases = []
+    for base in cls.__bases__:
+        if issubclass(base, dont):
+            bases.extend(want)
+            want = ()
+        else:
+            bases.append(base)
+    if want:
+        bases.extend(want)
+    bases = tuple(bases)
+
+    if cls.__bases__ != bases:
+        if ns is None:
+            ns = dict(cls.__dict__)
+            ns.pop("__module__", 1)
+        if obj is None:
+            cls = type(name, bases, ns)
+        else:
+            obj.__class__ = type(name, bases, ns)
+
+    return cls if obj is None else obj