Comparison for timedelta, time, date and datetime objects: __eq__ and

__ne__ no longer complain if they don't know how to compare to the other
thing.  If no meaningful way to compare is known, saying "not equal" is
sensible.  This allows things like

    if adatetime in some_sequence:
and
    somedict[adatetime] = whatever

to work as expected even if some_sequence contains non-datetime objects,
or somedict non-datetime keys, because they only call __eq__.

It still complains (raises TypeError) for mixed-type comparisons in
contexts that require a total ordering, such as list.sort(), use as a
key in a BTree-based data structure, and cmp().

1 files changed, 68 insertions, 18 deletions

diff --git a/Lib/test/test_datetime.py b/Lib/test/test_datetime.py
index 6acf073..8d6fe19 100644
--- a/Lib/test/test_datetime.py
+++ b/Lib/test/test_datetime.py
@@ -134,9 +134,51 @@ class TestTZInfo(unittest.TestCase):
                 self.assertEqual(derived.tzname(None), 'cookie')
 
 #############################################################################
+# Base clase for testing a particular aspect of timedelta, time, date and
+# datetime comparisons.
+
+class HarmlessMixedComparison(unittest.TestCase):
+    # Test that __eq__ and __ne__ don't complain for mixed-type comparisons.
+
+    # Subclasses must define 'theclass', and theclass(1, 1, 1) must be a
+    # legit constructor.
+
+    def test_harmless_mixed_comparison(self):
+        me = self.theclass(1, 1, 1)
+
+        self.failIf(me == ())
+        self.failUnless(me != ())
+        self.failIf(() == me)
+        self.failUnless(() != me)
+
+        self.failUnless(me in [1, 20L, [], me])
+        self.failIf(me not in [1, 20L, [], me])
+
+        self.failUnless([] in [me, 1, 20L, []])
+        self.failIf([] not in [me, 1, 20L, []])
+
+    def test_harmful_mixed_comparison(self):
+        me = self.theclass(1, 1, 1)
+
+        self.assertRaises(TypeError, lambda: me < ())
+        self.assertRaises(TypeError, lambda: me <= ())
+        self.assertRaises(TypeError, lambda: me > ())
+        self.assertRaises(TypeError, lambda: me >= ())
+
+        self.assertRaises(TypeError, lambda: () < me)
+        self.assertRaises(TypeError, lambda: () <= me)
+        self.assertRaises(TypeError, lambda: () > me)
+        self.assertRaises(TypeError, lambda: () >= me)
+
+        self.assertRaises(TypeError, cmp, (), me)
+        self.assertRaises(TypeError, cmp, me, ())
+
+#############################################################################
 # timedelta tests
 
-class TestTimeDelta(unittest.TestCase):
+class TestTimeDelta(HarmlessMixedComparison):
+
+    theclass = timedelta
 
     def test_constructor(self):
         eq = self.assertEqual
@@ -301,15 +343,18 @@ class TestTimeDelta(unittest.TestCase):
             self.assertEqual(cmp(t1, t2), -1)
             self.assertEqual(cmp(t2, t1), 1)
 
-        for badarg in 10, 10L, 34.5, "abc", {}, [], ():
-            self.assertRaises(TypeError, lambda: t1 == badarg)
-            self.assertRaises(TypeError, lambda: t1 != badarg)
+        badargs = 10, 10L, 34.5, "abc", {}, [], ()
+        for badarg in badargs:
+            self.assertEqual(t1 == badarg, False)
+            self.assertEqual(t1 != badarg, True)
+            self.assertEqual(badarg == t1, False)
+            self.assertEqual(badarg != t1, True)
+
+        for badarg in badargs:
             self.assertRaises(TypeError, lambda: t1 <= badarg)
             self.assertRaises(TypeError, lambda: t1 < badarg)
             self.assertRaises(TypeError, lambda: t1 > badarg)
             self.assertRaises(TypeError, lambda: t1 >= badarg)
-            self.assertRaises(TypeError, lambda: badarg == t1)
-            self.assertRaises(TypeError, lambda: badarg != t1)
             self.assertRaises(TypeError, lambda: badarg <= t1)
             self.assertRaises(TypeError, lambda: badarg < t1)
             self.assertRaises(TypeError, lambda: badarg > t1)
@@ -446,7 +491,7 @@ class TestDateOnly(unittest.TestCase):
         dt2 = dt - delta
         self.assertEqual(dt2, dt - days)
 
-class TestDate(unittest.TestCase):
+class TestDate(HarmlessMixedComparison):
     # Tests here should pass for both dates and datetimes, except for a
     # few tests that TestDateTime overrides.
 
@@ -853,15 +898,17 @@ class TestDate(unittest.TestCase):
             self.assertEqual(cmp(t1, t2), -1)
             self.assertEqual(cmp(t2, t1), 1)
 
-        for badarg in 10, 10L, 34.5, "abc", {}, [], ():
-            self.assertRaises(TypeError, lambda: t1 == badarg)
-            self.assertRaises(TypeError, lambda: t1 != badarg)
-            self.assertRaises(TypeError, lambda: t1 <= badarg)
+        badargs = 10, 10L, 34.5, "abc", {}, [], ()
+        for badarg in badargs:
+            self.assertEqual(t1 == badarg, False)
+            self.assertEqual(t1 != badarg, True)
+            self.assertEqual(badarg == t1, False)
+            self.assertEqual(badarg != t1, True)
+
+        for badarg in badargs:
             self.assertRaises(TypeError, lambda: t1 < badarg)
             self.assertRaises(TypeError, lambda: t1 > badarg)
             self.assertRaises(TypeError, lambda: t1 >= badarg)
-            self.assertRaises(TypeError, lambda: badarg == t1)
-            self.assertRaises(TypeError, lambda: badarg != t1)
             self.assertRaises(TypeError, lambda: badarg <= t1)
             self.assertRaises(TypeError, lambda: badarg < t1)
             self.assertRaises(TypeError, lambda: badarg > t1)
@@ -1361,7 +1408,7 @@ class TestDateTime(TestDate):
         alsobog = AlsoBogus()
         self.assertRaises(ValueError, dt.astimezone, alsobog) # also naive
 
-class TestTime(unittest.TestCase):
+class TestTime(HarmlessMixedComparison):
 
     theclass = time
 
@@ -1431,15 +1478,18 @@ class TestTime(unittest.TestCase):
         badargs = (10, 10L, 34.5, "abc", {}, [], ())
         if CMP_BUG_FIXED:
             badargs += (date(1, 1, 1), datetime(1, 1, 1, 1, 1), timedelta(9))
+
+        for badarg in badargs:
+            self.assertEqual(t1 == badarg, False)
+            self.assertEqual(t1 != badarg, True)
+            self.assertEqual(badarg == t1, False)
+            self.assertEqual(badarg != t1, True)
+
         for badarg in badargs:
-            self.assertRaises(TypeError, lambda: t1 == badarg)
-            self.assertRaises(TypeError, lambda: t1 != badarg)
             self.assertRaises(TypeError, lambda: t1 <= badarg)
             self.assertRaises(TypeError, lambda: t1 < badarg)
             self.assertRaises(TypeError, lambda: t1 > badarg)
             self.assertRaises(TypeError, lambda: t1 >= badarg)
-            self.assertRaises(TypeError, lambda: badarg == t1)
-            self.assertRaises(TypeError, lambda: badarg != t1)
             self.assertRaises(TypeError, lambda: badarg <= t1)
             self.assertRaises(TypeError, lambda: badarg < t1)
             self.assertRaises(TypeError, lambda: badarg > t1)