Bringing the code and test suite into line with doc and NEWS changes

checked in two days agao:

Refactoring of, and new rules for, dt.astimezone(tz).

dt must be aware now, and tz.utcoffset() and tz.dst() must not return None.
The old dt.astimezone(None) no longer works to change an aware datetime
into a naive datetime; use dt.replace(tzinfo=None) instead.

The tzinfo base class now supplies a new fromutc(self, dt) method, and
datetime.astimezone(tz) invokes tz.fromutc().  The default implementation
of fromutc() reproduces the same results as the old astimezone()
implementation, but tzinfo subclasses can override fromutc() if the
default implementation isn't strong enough to get the correct results
in all cases (for example, this may be necessary if a tzinfo subclass
models a time zone whose "standard offset" (wrt UTC) changed in some
year(s), or in some variations of double-daylight time -- the creativity
of time zone politics can't be captured in a single default implementation).
This commit is contained in:
Tim Peters 2003-01-23 16:36:11 +00:00
parent 9a7c96a2bc
commit 52dcce24e2
2 changed files with 216 additions and 119 deletions

View File

@ -1313,20 +1313,27 @@ class TestDateTime(TestDate):
self.assertRaises(ValueError, base.replace, year=2001)
def test_astimezone(self):
# Pretty boring! The TZ test is more interesting here.
# Pretty boring! The TZ test is more interesting here. astimezone()
# simply can't be applied to a naive object.
dt = self.theclass.now()
f = FixedOffset(44, "")
for dtz in dt.astimezone(f), dt.astimezone(tz=f):
self.failUnless(isinstance(dtz, datetime))
self.assertEqual(dt.date(), dtz.date())
self.assertEqual(dt.time(), dtz.time())
self.failUnless(dtz.tzinfo is f)
self.assertEqual(dtz.utcoffset(), timedelta(minutes=44))
self.assertRaises(TypeError, dt.astimezone) # not enough args
self.assertRaises(TypeError, dt.astimezone, f, f) # too many args
self.assertRaises(TypeError, dt.astimezone, dt) # arg wrong type
self.assertRaises(ValueError, dt.astimezone, f) # naive
self.assertRaises(ValueError, dt.astimezone, tz=f) # naive
class Bogus(tzinfo):
def utcoffset(self, dt): return None
def dst(self, dt): return timedelta(0)
bog = Bogus()
self.assertRaises(ValueError, dt.astimezone, bog) # naive
class AlsoBogus(tzinfo):
def utcoffset(self, dt): return timedelta(0)
def dst(self, dt): return None
alsobog = AlsoBogus()
self.assertRaises(ValueError, dt.astimezone, alsobog) # also naive
class TestTime(unittest.TestCase):
@ -2443,17 +2450,11 @@ class TestDateTimeTZ(TestDateTime, TZInfoBase):
dt = self.theclass.now(tzinfo=f44m)
self.failUnless(dt.tzinfo is f44m)
# Replacing with degenerate tzinfo doesn't do any adjustment.
for x in dt.astimezone(fnone), dt.astimezone(tz=fnone):
self.failUnless(x.tzinfo is fnone)
self.assertEqual(x.date(), dt.date())
self.assertEqual(x.time(), dt.time())
# Ditt with None tz.
x = dt.astimezone(tz=None)
self.failUnless(x.tzinfo is None)
self.assertEqual(x.date(), dt.date())
self.assertEqual(x.time(), dt.time())
# Ditto replacing with same tzinfo.
# Replacing with degenerate tzinfo raises an exception.
self.assertRaises(ValueError, dt.astimezone, fnone)
# Ditto with None tz.
self.assertRaises(TypeError, dt.astimezone, None)
# Replacing with same tzinfo makes no change.
x = dt.astimezone(dt.tzinfo)
self.failUnless(x.tzinfo is f44m)
self.assertEqual(x.date(), dt.date())
@ -2603,7 +2604,7 @@ class USTimeZone(tzinfo):
# Can't compare naive to aware objects, so strip the timezone from
# dt first.
if start <= dt.astimezone(None) < end:
if start <= dt.replace(tzinfo=None) < end:
return HOUR
else:
return ZERO
@ -2630,8 +2631,6 @@ class TestTimezoneConversions(unittest.TestCase):
# Conversion to our own timezone is always an identity.
self.assertEqual(dt.astimezone(tz), dt)
# Conversion to None is always the same as stripping tzinfo.
self.assertEqual(dt.astimezone(None), dt.replace(tzinfo=None))
asutc = dt.astimezone(utc)
there_and_back = asutc.astimezone(tz)
@ -2684,8 +2683,11 @@ class TestTimezoneConversions(unittest.TestCase):
# Conversion to our own timezone is always an identity.
self.assertEqual(dt.astimezone(tz), dt)
# Conversion to None is always the same as stripping tzinfo.
self.assertEqual(dt.astimezone(None), dt.replace(tzinfo=None))
# Converting to UTC and back is an identity too.
asutc = dt.astimezone(utc)
there_and_back = asutc.astimezone(tz)
self.assertEqual(dt, there_and_back)
def convert_between_tz_and_utc(self, tz, utc):
dston = self.dston.replace(tzinfo=tz)
@ -2737,7 +2739,7 @@ class TestTimezoneConversions(unittest.TestCase):
# 22:00 on day before daylight starts.
fourback = self.dston - timedelta(hours=4)
ninewest = FixedOffset(-9*60, "-0900", 0)
fourback = fourback.astimezone(ninewest)
fourback = fourback.replace(tzinfo=ninewest)
# 22:00-0900 is 7:00 UTC == 2:00 EST == 3:00 DST. Since it's "after
# 2", we should get the 3 spelling.
# If we plug 22:00 the day before into Eastern, it "looks like std
@ -2746,17 +2748,17 @@ class TestTimezoneConversions(unittest.TestCase):
# local clock jumps from 1 to 3). The point here is to make sure we
# get the 3 spelling.
expected = self.dston.replace(hour=3)
got = fourback.astimezone(Eastern).astimezone(None)
got = fourback.astimezone(Eastern).replace(tzinfo=None)
self.assertEqual(expected, got)
# Similar, but map to 6:00 UTC == 1:00 EST == 2:00 DST. In that
# case we want the 1:00 spelling.
sixutc = self.dston.replace(hour=6).astimezone(utc_real)
sixutc = self.dston.replace(hour=6, tzinfo=utc_real)
# Now 6:00 "looks like daylight", so the offset wrt Eastern is -4,
# and adding -4-0 == -4 gives the 2:00 spelling. We want the 1:00 EST
# spelling.
expected = self.dston.replace(hour=1)
got = sixutc.astimezone(Eastern).astimezone(None)
got = sixutc.astimezone(Eastern).replace(tzinfo=None)
self.assertEqual(expected, got)
# Now on the day DST ends, we want "repeat an hour" behavior.
@ -2798,6 +2800,66 @@ class TestTimezoneConversions(unittest.TestCase):
def dst(self, dt): return None
self.assertRaises(ValueError, now.astimezone, notok())
def test_fromutc(self):
self.assertRaises(TypeError, Eastern.fromutc) # not enough args
now = datetime.utcnow().replace(tzinfo=utc_real)
self.assertRaises(ValueError, Eastern.fromutc, now) # wrong tzinfo
now = now.replace(tzinfo=Eastern) # insert correct tzinfo
enow = Eastern.fromutc(now) # doesn't blow up
self.assertEqual(enow.tzinfo, Eastern) # has right tzinfo member
self.assertRaises(TypeError, Eastern.fromutc, now, now) # too many args
self.assertRaises(TypeError, Eastern.fromutc, date.today()) # wrong type
# Always converts UTC to standard time.
class FauxUSTimeZone(USTimeZone):
def fromutc(self, dt):
return dt + self.stdoffset
FEastern = FauxUSTimeZone(-5, "FEastern", "FEST", "FEDT")
# UTC 4:MM 5:MM 6:MM 7:MM 8:MM 9:MM
# EST 23:MM 0:MM 1:MM 2:MM 3:MM 4:MM
# EDT 0:MM 1:MM 2:MM 3:MM 4:MM 5:MM
# Check around DST start.
start = self.dston.replace(hour=4, tzinfo=Eastern)
fstart = start.replace(tzinfo=FEastern)
for wall in 23, 0, 1, 3, 4, 5:
expected = start.replace(hour=wall)
if wall == 23:
expected -= timedelta(days=1)
got = Eastern.fromutc(start)
self.assertEqual(expected, got)
expected = fstart + FEastern.stdoffset
got = FEastern.fromutc(fstart)
self.assertEqual(expected, got)
# Ensure astimezone() calls fromutc() too.
got = fstart.replace(tzinfo=utc_real).astimezone(FEastern)
self.assertEqual(expected, got)
start += HOUR
fstart += HOUR
# Check around DST end.
start = self.dstoff.replace(hour=4, tzinfo=Eastern)
fstart = start.replace(tzinfo=FEastern)
for wall in 0, 1, 1, 2, 3, 4:
expected = start.replace(hour=wall)
got = Eastern.fromutc(start)
self.assertEqual(expected, got)
expected = fstart + FEastern.stdoffset
got = FEastern.fromutc(fstart)
self.assertEqual(expected, got)
# Ensure astimezone() calls fromutc() too.
got = fstart.replace(tzinfo=utc_real).astimezone(FEastern)
self.assertEqual(expected, got)
start += HOUR
fstart += HOUR
def test_suite():
allsuites = [unittest.makeSuite(klass, 'test')

View File

@ -2725,24 +2725,106 @@ tzinfo_nogo(const char* methodname)
/* Methods. A subclass must implement these. */
static PyObject*
static PyObject *
tzinfo_tzname(PyDateTime_TZInfo *self, PyObject *dt)
{
return tzinfo_nogo("tzname");
}
static PyObject*
static PyObject *
tzinfo_utcoffset(PyDateTime_TZInfo *self, PyObject *dt)
{
return tzinfo_nogo("utcoffset");
}
static PyObject*
static PyObject *
tzinfo_dst(PyDateTime_TZInfo *self, PyObject *dt)
{
return tzinfo_nogo("dst");
}
static PyObject *
tzinfo_fromutc(PyDateTime_TZInfo *self, PyDateTime_DateTime *dt)
{
int y, m, d, hh, mm, ss, us;
PyObject *result;
int off, dst;
int none;
int delta;
if (! PyDateTime_Check(dt)) {
PyErr_SetString(PyExc_TypeError,
"fromutc: argument must be a datetime");
return NULL;
}
if (! HASTZINFO(dt) || dt->tzinfo != (PyObject *)self) {
PyErr_SetString(PyExc_ValueError, "fromutc: dt.tzinfo "
"is not self");
return NULL;
}
off = call_utcoffset(dt->tzinfo, (PyObject *)dt, &none);
if (off == -1 && PyErr_Occurred())
return NULL;
if (none) {
PyErr_SetString(PyExc_ValueError, "fromutc: non-None "
"utcoffset() result required");
return NULL;
}
dst = call_dst(dt->tzinfo, (PyObject *)dt, &none);
if (dst == -1 && PyErr_Occurred())
return NULL;
if (none) {
PyErr_SetString(PyExc_ValueError, "fromutc: non-None "
"dst() result required");
return NULL;
}
y = GET_YEAR(dt);
m = GET_MONTH(dt);
d = GET_DAY(dt);
hh = DATE_GET_HOUR(dt);
mm = DATE_GET_MINUTE(dt);
ss = DATE_GET_SECOND(dt);
us = DATE_GET_MICROSECOND(dt);
delta = off - dst;
mm += delta;
if ((mm < 0 || mm >= 60) &&
normalize_datetime(&y, &m, &d, &hh, &mm, &ss, &us) < 0)
goto Fail;
result = new_datetime(y, m, d, hh, mm, ss, us, dt->tzinfo);
if (result == NULL)
return result;
dst = call_dst(dt->tzinfo, result, &none);
if (dst == -1 && PyErr_Occurred())
goto Fail;
if (none)
goto Inconsistent;
if (dst == 0)
return result;
mm += dst;
if ((mm < 0 || mm >= 60) &&
normalize_datetime(&y, &m, &d, &hh, &mm, &ss, &us) < 0)
goto Fail;
Py_DECREF(result);
result = new_datetime(y, m, d, hh, mm, ss, us, dt->tzinfo);
return result;
Inconsistent:
PyErr_SetString(PyExc_ValueError, "fromutc: tz.dst() gave"
"inconsistent results; cannot convert");
/* fall thru to failure */
Fail:
Py_DECREF(result);
return NULL;
}
/*
* Pickle support. This is solely so that tzinfo subclasses can use
* pickling -- tzinfo itself is supposed to be uninstantiable. The
@ -2772,6 +2854,9 @@ static PyMethodDef tzinfo_methods[] = {
{"dst", (PyCFunction)tzinfo_dst, METH_O,
PyDoc_STR("datetime -> DST offset in minutes east of UTC.")},
{"fromutc", (PyCFunction)tzinfo_fromutc, METH_O,
PyDoc_STR("datetime in UTC -> datetime in local time.")},
{NULL, NULL}
};
@ -4036,109 +4121,59 @@ datetime_replace(PyDateTime_DateTime *self, PyObject *args, PyObject *kw)
static PyObject *
datetime_astimezone(PyDateTime_DateTime *self, PyObject *args, PyObject *kw)
{
int y = GET_YEAR(self);
int m = GET_MONTH(self);
int d = GET_DAY(self);
int hh = DATE_GET_HOUR(self);
int mm = DATE_GET_MINUTE(self);
int ss = DATE_GET_SECOND(self);
int us = DATE_GET_MICROSECOND(self);
int y, m, d, hh, mm, ss, us;
PyObject *result;
PyObject *temp;
int selfoff, resoff, dst1;
int none;
int delta;
int offset, none;
PyObject *tzinfo;
static char *keywords[] = {"tz", NULL};
if (! PyArg_ParseTupleAndKeywords(args, kw, "O:astimezone", keywords,
&tzinfo))
return NULL;
if (check_tzinfo_subclass(tzinfo) < 0)
if (! PyArg_ParseTupleAndKeywords(args, kw, "O!:astimezone", keywords,
&PyDateTime_TZInfoType, &tzinfo))
return NULL;
/* Don't call utcoffset unless necessary. */
if (!HASTZINFO(self) || self->tzinfo == Py_None)
goto NeedAware;
/* Conversion to self's own time zone is a NOP. */
if (self->tzinfo == tzinfo) {
Py_INCREF(self);
return (PyObject *)self;
}
/* Convert self to UTC. */
offset = call_utcoffset(self->tzinfo, (PyObject *)self, &none);
if (offset == -1 && PyErr_Occurred())
return NULL;
if (none)
goto NeedAware;
y = GET_YEAR(self);
m = GET_MONTH(self);
d = GET_DAY(self);
hh = DATE_GET_HOUR(self);
mm = DATE_GET_MINUTE(self);
ss = DATE_GET_SECOND(self);
us = DATE_GET_MICROSECOND(self);
mm -= offset;
if ((mm < 0 || mm >= 60) &&
normalize_datetime(&y, &m, &d, &hh, &mm, &ss, &us) < 0)
return NULL;
/* Attach new tzinfo and let fromutc() do the rest. */
result = new_datetime(y, m, d, hh, mm, ss, us, tzinfo);
if (result == NULL ||
tzinfo == Py_None ||
! HASTZINFO(self) ||
self->tzinfo == Py_None ||
self->tzinfo == tzinfo)
return result;
if (result != NULL) {
PyObject *temp = result;
/* Get the offsets. If either object turns out to be naive, again
* there's no conversion of date or time fields.
*/
selfoff = call_utcoffset(self->tzinfo, (PyObject *)self, &none);
if (selfoff == -1 && PyErr_Occurred())
goto Fail;
if (none)
return result;
resoff = call_utcoffset(tzinfo, result, &none);
if (resoff == -1 && PyErr_Occurred())
goto Fail;
if (none)
return result;
/* See the long comment block at the end of this file for an
* explanation of this algorithm. That it always works requires a
* pretty intricate proof. There are many equivalent ways to code
* up the proof as an algorithm. This way favors calling dst() over
* calling utcoffset(), because "the usual" utcoffset() calls dst()
* itself, and calling the latter instead saves a Python-level
* function call. This way of coding it also follows the proof
* closely, w/ x=self, y=result, z=result, and z'=temp.
*/
dst1 = call_dst(tzinfo, result, &none);
if (dst1 == -1 && PyErr_Occurred())
goto Fail;
if (none) {
PyErr_SetString(PyExc_ValueError, "astimezone(): utcoffset() "
"returned a duration but dst() returned None");
goto Fail;
result = PyObject_CallMethod(tzinfo, "fromutc", "O", temp);
Py_DECREF(temp);
}
delta = resoff - dst1 - selfoff;
if (delta) {
mm += delta;
if ((mm < 0 || mm >= 60) &&
normalize_datetime(&y, &m, &d, &hh, &mm, &ss, &us) < 0)
goto Fail;
temp = new_datetime(y, m, d, hh, mm, ss, us, tzinfo);
if (temp == NULL)
goto Fail;
Py_DECREF(result);
result = temp;
dst1 = call_dst(tzinfo, result, &none);
if (dst1 == -1 && PyErr_Occurred())
goto Fail;
if (none)
goto Inconsistent;
}
if (dst1 == 0)
return result;
mm += dst1;
if ((mm < 0 || mm >= 60) &&
normalize_datetime(&y, &m, &d, &hh, &mm, &ss, &us) < 0)
goto Fail;
temp = new_datetime(y, m, d, hh, mm, ss, us, tzinfo);
if (temp == NULL)
goto Fail;
Py_DECREF(result);
result = temp;
return result;
Inconsistent:
PyErr_SetString(PyExc_ValueError, "astimezone(): tz.dst() gave"
"inconsistent results; cannot convert");
/* fall thru to failure */
Fail:
Py_DECREF(result);
NeedAware:
PyErr_SetString(PyExc_ValueError, "astimezone() cannot be applied to "
"a naive datetime");
return NULL;
}