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

This commit is contained in:
Alexander Belopolsky 2012-06-08 12:33:09 -04:00
parent ed36b2e55b
commit a4415141da
5 changed files with 130 additions and 12 deletions
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44
Doc/library/datetime.rst
View File

@ -752,17 +752,6 @@ Other constructors, all class methods:
datetime(1970, 1, 1) + timedelta(seconds=timestamp)
There is no method to obtain the timestamp from a :class:`datetime`
instance, but POSIX timestamp corresponding to a :class:`datetime`
instance ``dt`` can be easily calculated as follows. For a naive
``dt``::
timestamp = (dt - datetime(1970, 1, 1)) / timedelta(seconds=1)
And for an aware ``dt``::
timestamp = (dt - datetime(1970, 1, 1, tzinfo=timezone.utc)) / timedelta(seconds=1)
.. versionchanged:: 3.3
Raise :exc:`OverflowError` instead of :exc:`ValueError` if the timestamp
is out of the range of values supported by the platform C
@ -1054,6 +1043,39 @@ Instance methods:
Return the proleptic Gregorian ordinal of the date. The same as
``self.date().toordinal()``.
.. method:: datetime.timestamp()
Return POSIX timestamp corresponding to the :class:`datetime`
instance. The return value is a :class:`float` similar to that
returned by :func:`time.time`.
Naive :class:`datetime` instances are assumed to represent local
time and this method relies on the platform C :c:func:`mktime`
function to perform the conversion. Since :class:`datetime`
supports wider range of values than :c:func:`mktime` on many
platforms, this method may raise :exc:`OverflowError` for times far
in the past or far in the future.
For aware :class:`datetime` instances, the return value is computed
as::
(dt - datetime(1970, 1, 1, tzinfo=timezone.utc)).total_seconds()
.. versionadded:: 3.3
.. note::
There is no method to obtain the POSIX timestamp directly from a
naive :class:`datetime` instance representing UTC time. If your
application uses this convention and your system timezone is not
set to UTC, you can obtain the POSIX timestamp by supplying
``tzinfo=timezone.utc``::
timestamp = dt.replace(tzinfo=timezone.utc).timestamp()
or by calculating the timestamp directly::
timestamp = (dt - datetime(1970, 1, 1)) / timedelta(seconds=1)
.. method:: datetime.weekday()

11
Lib/datetime.py
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@ -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.

36
Lib/test/datetimetester.py
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@ -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]:

2
Misc/NEWS
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@ -21,6 +21,8 @@ Core and Builtins
Library
-------
- Issue #2736: Added datetime.timestamp() method.
- Issue #13854: Make multiprocessing properly handle non-integer
non-string argument to SystemExit.

49
Modules/_datetimemodule.c
View File

@ -766,6 +766,8 @@ typedef struct
/* The interned UTC timezone instance */
static PyObject *PyDateTime_TimeZone_UTC;
/* The interned Epoch datetime instance */
static PyObject *PyDateTime_Epoch;
/* Create new timezone instance checking offset range. This
function does not check the name argument. Caller must assure
@ -4747,6 +4749,44 @@ datetime_timetuple(PyDateTime_DateTime *self)
dstflag);
}
static PyObject *
datetime_timestamp(PyDateTime_DateTime *self)
{
PyObject *result;
if (HASTZINFO(self) && self->tzinfo != Py_None) {
PyObject *delta;
delta = datetime_subtract((PyObject *)self, PyDateTime_Epoch);
if (delta == NULL)
return NULL;
result = delta_total_seconds(delta);
Py_DECREF(delta);
}
else {
struct tm time;
time_t timestamp;
memset((void *) &time, '\0', sizeof(struct tm));
time.tm_year = GET_YEAR(self) - 1900;
time.tm_mon = GET_MONTH(self) - 1;
time.tm_mday = GET_DAY(self);
time.tm_hour = DATE_GET_HOUR(self);
time.tm_min = DATE_GET_MINUTE(self);
time.tm_sec = DATE_GET_SECOND(self);
time.tm_wday = -1;
time.tm_isdst = -1;
timestamp = mktime(&time);
/* Return value of -1 does not necessarily mean an error, but tm_wday
* cannot remain set to -1 if mktime succeeded. */
if (timestamp == (time_t)(-1) && time.tm_wday == -1) {
PyErr_SetString(PyExc_OverflowError,
"timestamp out of range");
return NULL;
}
result = PyFloat_FromDouble(timestamp + DATE_GET_MICROSECOND(self) / 1e6);
}
return result;
}
static PyObject *
datetime_getdate(PyDateTime_DateTime *self)
{
@ -4894,6 +4934,9 @@ static PyMethodDef datetime_methods[] = {
{"timetuple", (PyCFunction)datetime_timetuple, METH_NOARGS,
PyDoc_STR("Return time tuple, compatible with time.localtime().")},
{"timestamp", (PyCFunction)datetime_timestamp, METH_NOARGS,
PyDoc_STR("Return POSIX timestamp as float.")},
{"utctimetuple", (PyCFunction)datetime_utctimetuple, METH_NOARGS,
PyDoc_STR("Return UTC time tuple, compatible with time.localtime().")},
@ -5151,6 +5194,12 @@ PyInit__datetime(void)
return NULL;
Py_DECREF(x);
/* Epoch */
PyDateTime_Epoch = new_datetime(1970, 1, 1, 0, 0, 0, 0,
PyDateTime_TimeZone_UTC);
if (PyDateTime_Epoch == NULL)
return NULL;
/* module initialization */
PyModule_AddIntConstant(m, "MINYEAR", MINYEAR);
PyModule_AddIntConstant(m, "MAXYEAR", MAXYEAR);