Issue #2736: Added datetime.timestamp() method.

2 files changed, 46 insertions, 1 deletions

diff --git a/Lib/datetime.py b/Lib/datetime.py
index 59f3c68..5d8d9b3 100644
--- a/Lib/datetime.py
+++ b/Lib/datetime.py
@@ -1434,6 +1434,15 @@ class datetime(date):
                                   self.hour, self.minute, self.second,
                                   dst)
 
+    def timestamp(self):
+        "Return POSIX timestamp as float"
+        if self._tzinfo is None:
+            return _time.mktime((self.year, self.month, self.day,
+                                 self.hour, self.minute, self.second,
+                                 -1, -1, -1)) + self.microsecond / 1e6
+        else:
+            return (self - _EPOCH).total_seconds()
+
     def utctimetuple(self):
         "Return UTC time tuple compatible with time.gmtime()."
         offset = self.utcoffset()
@@ -1889,7 +1898,7 @@ class timezone(tzinfo):
 timezone.utc = timezone._create(timedelta(0))
 timezone.min = timezone._create(timezone._minoffset)
 timezone.max = timezone._create(timezone._maxoffset)
-
+_EPOCH = datetime(1970, 1, 1, tzinfo=timezone.utc)
 """
 Some time zone algebra.  For a datetime x, let
     x.n = x stripped of its timezone -- its naive time.
diff --git a/Lib/test/datetimetester.py b/Lib/test/datetimetester.py
index 853806b..9d84b9d 100644
--- a/Lib/test/datetimetester.py
+++ b/Lib/test/datetimetester.py
@@ -1735,6 +1735,42 @@ class TestDateTime(TestDate):
         got = self.theclass.utcfromtimestamp(ts)
         self.verify_field_equality(expected, got)
 
+    # Run with US-style DST rules: DST begins 2 a.m. on second Sunday in
+    # March (M3.2.0) and ends 2 a.m. on first Sunday in November (M11.1.0).
+    @support.run_with_tz('EST+05EDT,M3.2.0,M11.1.0')
+    def test_timestamp_naive(self):
+        t = self.theclass(1970, 1, 1)
+        self.assertEqual(t.timestamp(), 18000.0)
+        t = self.theclass(1970, 1, 1, 1, 2, 3, 4)
+        self.assertEqual(t.timestamp(),
+                         18000.0 + 3600 + 2*60 + 3 + 4*1e-6)
+        # Missing hour defaults to standard time
+        t = self.theclass(2012, 3, 11, 2, 30)
+        self.assertEqual(self.theclass.fromtimestamp(t.timestamp()),
+                                  t + timedelta(hours=1))
+        # Ambiguous hour defaults to DST
+        t = self.theclass(2012, 11, 4, 1, 30)
+        self.assertEqual(self.theclass.fromtimestamp(t.timestamp()), t)
+
+        # Timestamp may raise an overflow error on some platforms
+        for t in [self.theclass(1,1,1), self.theclass(9999,12,12)]:
+            try:
+                s = t.timestamp()
+            except OverflowError:
+                pass
+            else:
+                self.assertEqual(self.theclass.fromtimestamp(s), t)
+
+    def test_timestamp_aware(self):
+        t = self.theclass(1970, 1, 1, tzinfo=timezone.utc)
+        self.assertEqual(t.timestamp(), 0.0)
+        t = self.theclass(1970, 1, 1, 1, 2, 3, 4, tzinfo=timezone.utc)
+        self.assertEqual(t.timestamp(),
+                         3600 + 2*60 + 3 + 4*1e-6)
+        t = self.theclass(1970, 1, 1, 1, 2, 3, 4,
+                          tzinfo=timezone(timedelta(hours=-5), 'EST'))
+        self.assertEqual(t.timestamp(),
+                         18000 + 3600 + 2*60 + 3 + 4*1e-6)
     def test_microsecond_rounding(self):
         for fts in [self.theclass.fromtimestamp,
                     self.theclass.utcfromtimestamp]: