[Python-checkins] bpo-32417: Make timedelta arithmetic respect subclasses (#10902)
Alexander Belopolsky
webhook-mailer at python.org
Mon Feb 4 14:42:10 EST 2019
https://github.com/python/cpython/commit/89427cd0feae25bbc8693abdccfa6a8c81a2689c
commit: 89427cd0feae25bbc8693abdccfa6a8c81a2689c
branch: master
author: Paul Ganssle <pganssle at users.noreply.github.com>
committer: Alexander Belopolsky <abalkin at users.noreply.github.com>
date: 2019-02-04T14:42:04-05:00
summary:
bpo-32417: Make timedelta arithmetic respect subclasses (#10902)
* Make timedelta return subclass types
Previously timedelta would always return the `date` and `datetime`
types, regardless of what it is added to. This makes it return
an object of the type it was added to.
* Add tests for timedelta arithmetic on subclasses
* Make pure python timedelta return subclass types
* Add test for fromtimestamp with tz argument
* Add tests for subclass behavior in now
* Add news entry.
Fixes:
bpo-32417
bpo-35364
* More descriptive variable names in tests
Addresses Victor's comments
files:
A Misc/NEWS.d/next/Library/2018-12-04-13-35-36.bpo-32417._Y9SKM.rst
M Lib/datetime.py
M Lib/test/datetimetester.py
M Modules/_datetimemodule.c
diff --git a/Lib/datetime.py b/Lib/datetime.py
index 4780b6df8f9b..89c32c0b0a63 100644
--- a/Lib/datetime.py
+++ b/Lib/datetime.py
@@ -1014,7 +1014,7 @@ def __add__(self, other):
if isinstance(other, timedelta):
o = self.toordinal() + other.days
if 0 < o <= _MAXORDINAL:
- return date.fromordinal(o)
+ return type(self).fromordinal(o)
raise OverflowError("result out of range")
return NotImplemented
@@ -2024,10 +2024,10 @@ def __add__(self, other):
hour, rem = divmod(delta.seconds, 3600)
minute, second = divmod(rem, 60)
if 0 < delta.days <= _MAXORDINAL:
- return datetime.combine(date.fromordinal(delta.days),
- time(hour, minute, second,
- delta.microseconds,
- tzinfo=self._tzinfo))
+ return type(self).combine(date.fromordinal(delta.days),
+ time(hour, minute, second,
+ delta.microseconds,
+ tzinfo=self._tzinfo))
raise OverflowError("result out of range")
__radd__ = __add__
diff --git a/Lib/test/datetimetester.py b/Lib/test/datetimetester.py
index d729c7efd52f..958b33675c37 100644
--- a/Lib/test/datetimetester.py
+++ b/Lib/test/datetimetester.py
@@ -820,6 +820,44 @@ def as_hours(self):
self.assertEqual(str(t3), str(t4))
self.assertEqual(t4.as_hours(), -1)
+ def test_subclass_date(self):
+ class DateSubclass(date):
+ pass
+
+ d1 = DateSubclass(2018, 1, 5)
+ td = timedelta(days=1)
+
+ tests = [
+ ('add', lambda d, t: d + t, DateSubclass(2018, 1, 6)),
+ ('radd', lambda d, t: t + d, DateSubclass(2018, 1, 6)),
+ ('sub', lambda d, t: d - t, DateSubclass(2018, 1, 4)),
+ ]
+
+ for name, func, expected in tests:
+ with self.subTest(name):
+ act = func(d1, td)
+ self.assertEqual(act, expected)
+ self.assertIsInstance(act, DateSubclass)
+
+ def test_subclass_datetime(self):
+ class DateTimeSubclass(datetime):
+ pass
+
+ d1 = DateTimeSubclass(2018, 1, 5, 12, 30)
+ td = timedelta(days=1, minutes=30)
+
+ tests = [
+ ('add', lambda d, t: d + t, DateTimeSubclass(2018, 1, 6, 13)),
+ ('radd', lambda d, t: t + d, DateTimeSubclass(2018, 1, 6, 13)),
+ ('sub', lambda d, t: d - t, DateTimeSubclass(2018, 1, 4, 12)),
+ ]
+
+ for name, func, expected in tests:
+ with self.subTest(name):
+ act = func(d1, td)
+ self.assertEqual(act, expected)
+ self.assertIsInstance(act, DateTimeSubclass)
+
def test_division(self):
t = timedelta(hours=1, minutes=24, seconds=19)
second = timedelta(seconds=1)
@@ -2604,33 +2642,58 @@ def __new__(cls, *args, **kwargs):
ts = base_d.timestamp()
test_cases = [
- ('fromtimestamp', (ts,)),
+ ('fromtimestamp', (ts,), base_d),
# See https://bugs.python.org/issue32417
- # ('fromtimestamp', (ts, timezone.utc)),
- ('utcfromtimestamp', (utc_ts,)),
- ('fromisoformat', (d_isoformat,)),
- ('strptime', (d_isoformat, '%Y-%m-%dT%H:%M:%S.%f')),
- ('combine', (date(*args[0:3]), time(*args[3:]))),
+ ('fromtimestamp', (ts, timezone.utc),
+ base_d.astimezone(timezone.utc)),
+ ('utcfromtimestamp', (utc_ts,), base_d),
+ ('fromisoformat', (d_isoformat,), base_d),
+ ('strptime', (d_isoformat, '%Y-%m-%dT%H:%M:%S.%f'), base_d),
+ ('combine', (date(*args[0:3]), time(*args[3:])), base_d),
]
- for constr_name, constr_args in test_cases:
+ for constr_name, constr_args, expected in test_cases:
for base_obj in (DateTimeSubclass, base_d):
# Test both the classmethod and method
with self.subTest(base_obj_type=type(base_obj),
constr_name=constr_name):
- constr = getattr(base_obj, constr_name)
+ constructor = getattr(base_obj, constr_name)
- dt = constr(*constr_args)
+ dt = constructor(*constr_args)
# Test that it creates the right subclass
self.assertIsInstance(dt, DateTimeSubclass)
# Test that it's equal to the base object
- self.assertEqual(dt, base_d.replace(tzinfo=None))
+ self.assertEqual(dt, expected)
# Test that it called the constructor
self.assertEqual(dt.extra, 7)
+ def test_subclass_now(self):
+ # Test that alternate constructors call the constructor
+ class DateTimeSubclass(self.theclass):
+ def __new__(cls, *args, **kwargs):
+ result = self.theclass.__new__(cls, *args, **kwargs)
+ result.extra = 7
+
+ return result
+
+ test_cases = [
+ ('now', 'now', {}),
+ ('utcnow', 'utcnow', {}),
+ ('now_utc', 'now', {'tz': timezone.utc}),
+ ('now_fixed', 'now', {'tz': timezone(timedelta(hours=-5), "EST")}),
+ ]
+
+ for name, meth_name, kwargs in test_cases:
+ with self.subTest(name):
+ constr = getattr(DateTimeSubclass, meth_name)
+ dt = constr(**kwargs)
+
+ self.assertIsInstance(dt, DateTimeSubclass)
+ self.assertEqual(dt.extra, 7)
+
def test_fromisoformat_datetime(self):
# Test that isoformat() is reversible
base_dates = [
diff --git a/Misc/NEWS.d/next/Library/2018-12-04-13-35-36.bpo-32417._Y9SKM.rst b/Misc/NEWS.d/next/Library/2018-12-04-13-35-36.bpo-32417._Y9SKM.rst
new file mode 100644
index 000000000000..cfc4fbe2e686
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2018-12-04-13-35-36.bpo-32417._Y9SKM.rst
@@ -0,0 +1,6 @@
+Performing arithmetic between :class:`datetime.datetime` subclasses and
+:class:`datetime.timedelta` now returns an object of the same type as the
+:class:`datetime.datetime` subclass. As a result,
+:meth:`datetime.datetime.astimezone` and alternate constructors like
+:meth:`datetime.datetime.now` and :meth:`datetime.fromtimestamp` called with
+a ``tz`` argument now *also* retain their subclass.
diff --git a/Modules/_datetimemodule.c b/Modules/_datetimemodule.c
index 7997758908bb..c1557b5e6f49 100644
--- a/Modules/_datetimemodule.c
+++ b/Modules/_datetimemodule.c
@@ -3004,7 +3004,8 @@ add_date_timedelta(PyDateTime_Date *date, PyDateTime_Delta *delta, int negate)
int day = GET_DAY(date) + (negate ? -deltadays : deltadays);
if (normalize_date(&year, &month, &day) >= 0)
- result = new_date(year, month, day);
+ result = new_date_subclass_ex(year, month, day,
+ (PyObject* )Py_TYPE(date));
return result;
}
@@ -5166,9 +5167,10 @@ add_datetime_timedelta(PyDateTime_DateTime *date, PyDateTime_Delta *delta,
return NULL;
}
- return new_datetime(year, month, day,
- hour, minute, second, microsecond,
- HASTZINFO(date) ? date->tzinfo : Py_None, 0);
+ return new_datetime_subclass_ex(year, month, day,
+ hour, minute, second, microsecond,
+ HASTZINFO(date) ? date->tzinfo : Py_None,
+ (PyObject *)Py_TYPE(date));
}
static PyObject *
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