Mark treatment of binary operators for __rop__-before-__op__ as done.

Add more detail about the speed optimizations needed for __dynamic__.
The weak reference solution becomes more attractive...

PLAN.txt

@@ -4,13 +4,19 @@ Project: core implementation
 Still to do
 -----------
 
-Treat all binary operators the same way as I just did for rich
-comparison: in a <op> b, if isinstance(b, type(a)), try b.__rop__(a)
-before trying a.__op__(b).
-
 Make __dynamic__ the default (this requires more performance work --
 one particular test, test_descr.inherits(), is about 10x slower when
-__dynamic__ is 1. :-(
+__dynamic__ is 1. :-(  There are two ways to go about the performance
+work:
+
+ a) Add shortcuts to the slot_tp_XXX to recognize a PyWrapperDescr
+    with the correct wrap_tp_XXX function.
+
+ b) Add a list or dict of weak refs to derived classes to each dynamic
+    class, and trap setattr+delattr on the base class so that they
+    update the tp_XXX slot in each derived class when the base class
+    __XXX__ gets set or deleted.  More work, but more gain (zero waste
+    in slot_tp_XXX when __XXX__ is not overridden).
 
 Add __del__ handlers.
 
@@ -33,6 +39,10 @@ implemented.
 Done (mostly)
 -------------
 
+Treat all binary operators the same way as I just did for rich
+comparison: in a <op> b, if type(a) is not type(b) and isinstance(b,
+type(a)), try b.__rop__(a) before trying a.__op__(b).  *** Done. ***
+
 Fix comparisons.  There's some nasty stuff here: when two types are
 not the same, and they're not instances, the fallback code doesn't
 account for the possibility that they might be subtypes of a common