Introducing __reduce_ex__, which is called with a protocol number argument
if it exists in preference over __reduce__. Now Tim can go implement this
in cPickle.c.
diff --git a/Lib/pickle.py b/Lib/pickle.py
index c62bddc..f997f38 100644
--- a/Lib/pickle.py
+++ b/Lib/pickle.py
@@ -304,21 +304,20 @@
# Check copy_reg.dispatch_table
reduce = dispatch_table.get(t)
- if not reduce:
- # Check for a __reduce__ method.
- # Subtle: get the unbound method from the class, so that
- # protocol 2 can override the default __reduce__ that all
- # classes inherit from object. This has the added
- # advantage that the call always has the form reduce(obj)
- reduce = getattr(t, "__reduce__", None)
- if self.proto >= 2:
- # Protocol 2 can do better than the default __reduce__
- if reduce is object.__reduce__:
- reduce = _better_reduce
- if not reduce:
- raise PicklingError("Can't pickle %r object: %r" %
- (t.__name__, obj))
- rv = reduce(obj)
+ if reduce:
+ rv = reduce(obj)
+ else:
+ # Check for a __reduce_ex__ method, fall back to __reduce__
+ reduce = getattr(obj, "__reduce_ex__", None)
+ if reduce:
+ rv = reduce(self.proto)
+ else:
+ reduce = getattr(obj, "__reduce__", None)
+ if reduce:
+ rv = reduce()
+ else:
+ raise PicklingError("Can't pickle %r object: %r" %
+ (t.__name__, obj))
# Check for string returned by reduce(), meaning "save as global"
if type(rv) is StringType: