datetime.timedelta is now subclassable in Python. The new test shows
one good use: a subclass adding a method to express the duration as
a number of hours (or minutes, or whatever else you want to add). The
native breakdown into days+seconds+us is often clumsy. Incidentally
moved a large chunk of object-initialization code closer to the top of
the file, to avoid worse forward-reference trickery.
diff --git a/Lib/test/test_datetime.py b/Lib/test/test_datetime.py
index c4978f3..cca0c9d 100644
--- a/Lib/test/test_datetime.py
+++ b/Lib/test/test_datetime.py
@@ -443,6 +443,37 @@
self.failUnless(timedelta(microseconds=1))
self.failUnless(not timedelta(0))
+ def test_subclass_timedelta(self):
+
+ class T(timedelta):
+ def from_td(td):
+ return T(td.days, td.seconds, td.microseconds)
+ from_td = staticmethod(from_td)
+
+ def as_hours(self):
+ sum = (self.days * 24 +
+ self.seconds / 3600.0 +
+ self.microseconds / 3600e6)
+ return round(sum)
+
+ t1 = T(days=1)
+ self.assert_(type(t1) is T)
+ self.assertEqual(t1.as_hours(), 24)
+
+ t2 = T(days=-1, seconds=-3600)
+ self.assert_(type(t2) is T)
+ self.assertEqual(t2.as_hours(), -25)
+
+ t3 = t1 + t2
+ self.assert_(type(t3) is timedelta)
+ t4 = T.from_td(t3)
+ self.assert_(type(t4) is T)
+ self.assertEqual(t3.days, t4.days)
+ self.assertEqual(t3.seconds, t4.seconds)
+ self.assertEqual(t3.microseconds, t4.microseconds)
+ self.assertEqual(str(t3), str(t4))
+ self.assertEqual(t4.as_hours(), -1)
+
#############################################################################
# date tests