py2/py3: define OrderableKey that uses legacy cmp for ordering.

product/ERP5Type/Utils.py

@@ -144,6 +144,19 @@ else:
 # Generic sort method
 #####################################################
 
+if six.PY2:
+  OrderableKey = lambda x: x
+else:
+  class OrderableKey(object):
+    def __init__(self, value):
+      self.value = value
+
+    def __lt__(self, other):
+      return cmp(self.value, other.value) != 1
+
+    def __repr__(self):
+      return 'OrderableKey(%r)' % self.value
+
 sort_kw_cache = {}
 
 def sortValueList(value_list, sort_on=None, sort_order=None, **kw):
@@ -201,7 +214,10 @@ def sortValueList(value_list, sort_on=None, sort_order=None, **kw):
               except TypeError:
                 pass
             value_list.append(x)
-          return value_list
+          if six.PY2:
+            return value_list
+          else:
+            return [OrderableKey(e) for e in value_list]
         sort_kw = {'key':sortValue, 'reverse':reverse}
         sort_kw_cache[(sort_on, sort_order)] = sort_kw
       else:

product/ERP5Type/tests/testERP5Type.py

@@ -38,7 +38,7 @@ from Acquisition import aq_base
 from Products.ERP5Type.tests.ERP5TypeTestCase import ERP5TypeTestCase
 from AccessControl.ZopeGuards import guarded_import
 from Products.ERP5Type.tests.utils import LogInterceptor, createZODBPythonScript
-from Products.ERP5Type.Utils import cmp
+from Products.ERP5Type.Utils import OrderableKey, cmp
 
 class TestERP5Type(ERP5TypeTestCase, LogInterceptor):
     """
@@ -286,6 +286,16 @@ class TestERP5Type(ERP5TypeTestCase, LogInterceptor):
       self.assertEqual(cmp(None, ''), -1)
       self.assertEqual(cmp(0, ''), -1)
 
+    def test_OrderableKey(self):
+      self.assertEqual(
+        sorted([1, '', None], key=lambda x: OrderableKey(x)),
+        [None, 1, '']
+      )
+      o1 = [OrderableKey(e) for e in (None, 1)]
+      o2 = [OrderableKey(e) for e in (0, 0)]
+      self.assertEqual(sorted([o1, o2]), [o1, o2])
+      self.assertEqual(sorted([o2, o1]), [o1, o2])
+
 def test_suite():
   suite = unittest.TestSuite()
   suite.addTest(unittest.makeSuite(TestERP5Type))