fix parameter inheritance using MRO

+ no update on unhchanged values within 1 sec

Change-Id: I3e3d50bb5541e8d4da2badc3133d243dd0a3b892

test/test_properties.py

@@ -159,3 +159,26 @@ def test_Property_override():
             a = 's'
 
     assert 'can not set' in str(e.value)
+
+
+def test_Properties_mro():
+    class A(HasProperties):
+        p = Property('base', StringType(), 'base', export='always')
+
+    class B(A):
+        pass
+
+    class C(A):
+        p = Property('sub', FloatRange(), extname='p')
+
+    class D(C, B):
+        p = 1
+
+    class E(B, C):
+        p = 2
+
+    assert B().exportProperties() == {'_p': 'base'}
+    assert D().exportProperties() == {'p': 1.0}
+    # in an older implementation the following would fail, as B.p is constructed first
+    # and then B.p overrides C.p
+    assert E().exportProperties() == {'p': 2.0}