"Fix" for SF bug #520644: __slots__ are not pickled.
As promised in my response to the bug report, I'm not really fixing
it; in fact, one could argule over what the proper fix should do.
Instead, I'm adding a little magic that raises TypeError if you try to
pickle an instance of a class that has __slots__ but doesn't define or
override __getstate__. This is done by adding a bozo __getstate__
that always raises TypeError.
Bugfix candidate (also the checkin to typeobject.c, of course).
diff --git a/Lib/test/test_descr.py b/Lib/test/test_descr.py
index 7e48884..1188e1d 100644
--- a/Lib/test/test_descr.py
+++ b/Lib/test/test_descr.py
@@ -2450,6 +2450,94 @@
print "a = x =", a
print "b = y =", b
+def pickleslots():
+ if verbose: print "Testing pickling of classes with __slots__ ..."
+ import pickle, cPickle
+ # Pickling of classes with __slots__ but without __getstate__ should fail
+ global B, C, D, E
+ class B(object):
+ pass
+ for base in [object, B]:
+ class C(base):
+ __slots__ = ['a']
+ class D(C):
+ pass
+ try:
+ pickle.dumps(C())
+ except TypeError:
+ pass
+ else:
+ raise TestFailed, "should fail: pickle C instance - %s" % base
+ try:
+ cPickle.dumps(C())
+ except TypeError:
+ pass
+ else:
+ raise TestFailed, "should fail: cPickle C instance - %s" % base
+ try:
+ pickle.dumps(C())
+ except TypeError:
+ pass
+ else:
+ raise TestFailed, "should fail: pickle D instance - %s" % base
+ try:
+ cPickle.dumps(D())
+ except TypeError:
+ pass
+ else:
+ raise TestFailed, "should fail: cPickle D instance - %s" % base
+ # Give C a __getstate__ and __setstate__
+ class C(base):
+ __slots__ = ['a']
+ def __getstate__(self):
+ try:
+ d = self.__dict__.copy()
+ except AttributeError:
+ d = {}
+ try:
+ d['a'] = self.a
+ except AttributeError:
+ pass
+ return d
+ def __setstate__(self, d):
+ for k, v in d.items():
+ setattr(self, k, v)
+ class D(C):
+ pass
+ # Now it should work
+ x = C()
+ y = pickle.loads(pickle.dumps(x))
+ vereq(hasattr(y, 'a'), 0)
+ y = cPickle.loads(cPickle.dumps(x))
+ vereq(hasattr(y, 'a'), 0)
+ x.a = 42
+ y = pickle.loads(pickle.dumps(x))
+ vereq(y.a, 42)
+ y = cPickle.loads(cPickle.dumps(x))
+ vereq(y.a, 42)
+ x = D()
+ x.a = 42
+ x.b = 100
+ y = pickle.loads(pickle.dumps(x))
+ vereq(y.a + y.b, 142)
+ y = cPickle.loads(cPickle.dumps(x))
+ vereq(y.a + y.b, 142)
+ # But a subclass that adds a slot should not work
+ class E(C):
+ __slots__ = ['b']
+ try:
+ pickle.dumps(E())
+ except TypeError:
+ pass
+ else:
+ raise TestFailed, "should fail: pickle E instance - %s" % base
+ try:
+ cPickle.dumps(E())
+ except TypeError:
+ pass
+ else:
+ raise TestFailed, "should fail: cPickle E instance - %s" % base
+
def copies():
if verbose: print "Testing copy.copy() and copy.deepcopy()..."
import copy
@@ -2798,6 +2886,7 @@
strops()
deepcopyrecursive()
modules()
+ pickleslots()
if verbose: print "All OK"
if __name__ == "__main__":